Full-fat tadpole tandem trike - build log

kiltedcelt

100 W
Joined
Aug 19, 2015
Messages
158
Location
Chicago, IL USA
I've embarked on creating what might be the most outlandish tandem trike ever created and decided to share a build log with all you fine folks. I hope you'll enjoy seeing the progress of the build. Feel free to chime in with questions as I post updates.

First, a little background. I've been fascinated by recumbents ever since seeing a film about the first HPV event back in the early 80s in high school science class. I still wish I could find that film on YouTube or something but I've not had any luck though I periodically search for it. Who knows, it might have been a NOVA program and we watched it on VHS or something. This was probably about 35/36 years ago so, anyway... What I remember about this video was all the cool HPV vehicles. Some were insane tandem streamlined velomobiles built for speed, while others were little more than 10 speed road bikes with janky aero covers built over them. That little taste was enough to pique my interest in recumbents though it wasn't until a few years ago that I bought my first recumbent.

I'd been commuting to work and living a mostly car-free lifestyle when saddle discomfort issues finally got me to consider buying a 'bent. I went to a local shop (Amling's near Chicago), and ended up buying a Bacchetta Giro 20. I rode that Giro for about 7 months or so before later selling it and going back to riding regular "upright" bikes for the next few years. In those intervening years I still continued to search for the perfect saddle, fiddled with bike fit, but still never had anything that I could stand being on for more than about 30 miles. As I racked up the 2-wheel miles, I also had numerous crashes (never with cars, just solo wipeouts), that resulted in the worst cases a broken rib, a badly messed up wrist (that one was actually the result of carrying a bike into my apartment), and a badly jacked up knee. The final straw was riding my cargo bike (that I built myself), through a pothole last year. The subsequent health issues from taking a saddle to the nethers at speed and with substantial force eventually subsided, but not before I thought at length about my lifetime of cycling, my car-free living of the last 10 years, and ultimately *what* I personally wanted from a human-powered-wheeled-conveyance, especially since I was looking for a new project to build.

So, that brings me to the latest project. I decided that I've had my fill of falls and spills. I also disliked how unstable a heavily loaded two-wheeled cargo bike can be. There were a few times when I had a load of tools or construction materials on my cargo bike and managed to dump it in the middle of the road, or even just trying pull away from a stop after loading. So, my future vehicle I decided needed to be recumbent to eliminate those lower back and saddle-related issues I'd struggled with for a number of years, and a trike for the sake of stability and greatly-lessened likelihood tip-over/crashes/etc related to wet-pavement, ice, etc

I also wanted the trike to be able to haul cargo and so that led me to thinking of either tadpole or quad design. Ultimately, I ruled out quads because they're uncommon enough here in the U.S. that I didn't want to having any issues with whether I could utilize cycling infrastructure, especially since this would also be Class 2 e-assist. Tadpole configuration seemed most logical since even unloaded, the force of the braking would be on the front two wheels, versus a single front wheel and two rear wheels as in a delta configuration. When the trike would be mostly unloaded, a delta would not have as much braking force, whereas the tadpole would always have more stopping power, even when unloaded.

At some point during the design phase I got the idea to make it tandem and have the stoker seat removeable so the trike could be converted to single-rider cargo-hauling duty. That is the current configuration of the design. A few other things became major considerations as well while designing the end-product. One major thing was making the ride comfortable without needing costly/complex suspension systems. From all my work on building my own bikes and fabricating my cargo bike, I decided to go with a full-fat tubeless system, but also being able to easily build a second set of wheels for a mid-fat option. As I wanted the most versatility, I chose to build the full-fat wheels to begin with. I had a Pugsley fat bike that I commuted 100 miles per week on all of a year or so in Chicago, and found it was very comfortable and the 4.0 off-road tread suffered very little wear from all the pavement riding.

So, that's all the background - design philosophy, etc. The closest thing I've even found that resembles what I'm building is a custom quad built by the folks at Utah Trikes. Just imagine this with a single rear wheel and almost everything else would be the same.

OH4opTgeDFNScVwhRiJXXPh9EO36kg4E-_P2qta2XjPu1MuClLrlXsE8PPRFxt5RMnD2oNJhJxBUba7hlS6xYvxROTC27W3f5m4fOWSXmx9_EdvoStWcvXWq6TiO9HoIVGSIZ1ikctWM4x3cOa3eIYg_fcYowECC5df5l_utck4PpLv9cRX9GjhS-z2oRpUaWd4iFYK0PB3Lxq_FNIMNKbYKyKML-B-SkvDGWhyiH1WQCMq5HUeDQ3ONOyQs3TtXXPbU0wT6X-4T1CIMXuuQBexNhNYRU54gRZXue1NW5V2QczUTQRsIiM0Ok58E8pZfJrHDaKg12r65gJ7Kn72u7l2uhdwcNhdutYRqCKrAr_QRmv8X8s_EgGHKeMfDYJdRGTO0QWdmj16PpaxJVXsZjkrb7E0YtXu_DgfFXZ--2xJ71RS3IsWzr-23BY8Q_XLRrPsME0Pc5lYNRGqSkUVW14iuHe-MmW7445UZjb9kCVAL53RdqQM3CvEKGLcPsMleaA-KNnfOM8CTVGUnCrG9f4twqjw08xVOwgs8GY6EETDUnN0GjtBBMfSRxwRb1M9VKaSnQjLnsG6p0mNyIqSsIlPUcgicHmQ5EeuRbH3o-1z9XqLGGlvO9n-8LN_dLEKnR5pZuEQ564bCtVbOy-5WR0pPSv9-VHju0OcakCX6C2nAiLOhWSUt12vXuiTbsYgTqYYR8oADSzRG0qT4oMCYWZLrrg=w749-h413-no
 
The first thing I had to do was figure out how to design what was probably the single most complex part of the build - the front-end steering assembly. I had purchased some Atomic Zombie plans for both his Warrior trike and his Viking tandem. In the end I chose to create my own design. I didn't want the complexity of indirect steering, and I also wanted to save a bit of fabrication work for myself. In the end, I purchased some Sun EZ Tad kingpins and direct steering arms from Utah Trikes along with the axles designed to work with the kingpins. Alas, the first stumbling block was that the Utah Trikes axles were intended for the hubs they use on the Sun trikes. Those are 15mm axles and would *not* work with the 75mm wide 20mm thru-axle Velocity hubs I'd acquired in a parts-dump from another Bentrider user. I'd acquired a bunch of parts - wheel hubs, front steering assemblies, seats, that were from a pair of early model trikes from Terra Trike (?).

So, I reached out to a friend who is an amateur machinist and asked her if she could fabricate some custom axles for me. She agreed, and I sent her a detailed measured drawing showing what I'd need to step my 20mm hubs down to the 15mm required by the Utah kingpins. She was able to to create a Fusion 360 file and with an .stl file derived from that, I was able to print a pair of axles in PLA filament to at least help me mock-up things to get some dimensions.

I was able to cipher out the measurements I wanted, the main thing being NOT to exceed 34" which would allow me to still get the trike into the bike room at my apartment building, but more importantly would make the trike able to use any existing cycling infrastructure, especially bi-directional bike lanes. I used standard 4130 cro-moly generic head tubes bought from a frame-builder supply and cut one down to create both head tubes. I'm MIG welding all of this frame, but it can be a little dicey when mating the much thinner 4130 cro-moly to the 16 gauge mild steel square tubing. The 4130 heats up much more quickly and if you're not careful you can get burn-through. I used an on/off pulsed MIG welding technique and was able to get a good weld without burning through anything.

When I weld in the bottom brackets, I might end up TIG welding instead as that allows much more control, or alternatively I have a pipe expander tool that can act as a big heatsink which can prevent distortion of the thinner metal of the bottom bracket shells. I'll probably try an experiment with a junk BB from my pile of frame scraps and see how that works with the heat sink mated to the 16 gauge tube before committing to my virgin BB shells.

Anyway, here's the finished front steering assembly mocked-up with the 3D-printed axles. The wheels were custom-built by yours truly. They are Weinmann 32 hole, laced symmetrically with Sapim Strong single-butted spokes. Tires are Schwalbe Jumbo Jim in 26x4.0, currently set up for convenience with inner tubes, but the plan is to set them up tubeless once the trike has been completed and ridden a fair bit to test everything out. Tubeless gives a much better ride, lowers weight and rolling resistance, and best of all, the sealant in the tires negates tube punctures in all but the worst cases.

GN8qcaoPNiSIk52YLiYcB1vkCiwLUXAoFxH4Iy7Og7QqBwI65rxaaqEzP_8UvgHBGKKabU_7WiVBFTJiJOrFBZawktG4W4P4dnKXvbi-RZWfRhPePgCRl4HpfzHJ3bVJd26ThMWFgu-T-aByA9OoZUmgq3kwfoHZFuth8iKo5dRGK3VVGbSVGSsHt07fSm58AfQXWDMJVqV8qkuiHh4SVP0x934fnikjxXl7Jxil6-sz6Xe6J5vnHlA7XlIJRkpAYt2ddlnrocG14mbcAopARUZGjyJ2z6VVVg0xa1jRdEO4GXPvtDBbeSG1V0JT6ZgHhxRmmGH5yMvbWFgfOUB3yfAEkv-fJj1ALXYejRzZtk9ild1FkJufI2r3Azu_621KcBzUduV7Si8cWhpE9tooo91PBcPfR8rtFjGkYcczK5P0IPxpOXsAr_c43hYG204f6GGgt738ECGGdt3mmAT16wDBoC-KIMwrnXZX_dMY3w_fGfKRdfKsiJ7LtCTtjz_sYwtgQ8_Z1E8ASqzCFfFY56tRHRkl9HwmX4cdrXtMhtOAOraCWE2P1WNczqCHnmc-u7Qjs0w6RY_9r8MnygQEF0QZXlGZXX23aF15EBfZaSffzVsnvb2v34G5Ci9V-_Uw_QdSwycyp70urvQ6ErfYqSCnG75r6LMAxL5z_xr6GaHdFsZP4xK4zLTUkZ3pOO1qwpPgfIiRGv8Ua8fq2FddXjoeWQ=w602-h802-no
 
Next up, after welding the front cross-member and head tube assemblies that makes up the whole steering assembly, was the beginning of the fabrication of the rest of the main body of the frame. Here, I was taking my cue from another Utah Trikes product, namely the UT Custom T2 Tandem. They appear to be utilizing a similar 1 1/2" square cross-section tube, although I have no idea whether their frames are made with mild-steel or whether it's 4130 cro-moly. I suspect they're probably mild-steel, otherwise they'd trumpet the lighter weight 4130 construction in their description. Also, I suspect their price would be considerably higher. Just look at tandems like Co-Motion which is made from round 4130 to see how expensive that can be! I did price out 4130 and it was prohibitively expensive.

I was able to buy all the mild-steel I needed for around $120, but 4130 cro-moly was on the order of something like $1000 or so. Definitely out of budget for this project. Anyway, like on the UT Custom, I chose to stack two pieces of 1 1/2" square tubing. I did not turn my lower on end as they did though. A few folks I know who know metal fabrication better than me said turning a tube slightly off-axis to the other as the UT Custom one has, only adds marginal extra strength.

zYddSq-5PNd5cyfEulVu5LxOgTPFsTAyRA1u9BKAGs-AbPxyI8W4LTcwng75vl2kGAzHg4jVIU-MjivhBEbglsShaYmGSsndMHuMXmtiPNvcCSTrC8QFTFJClENVDe-nXNGfNEztoJDcWJuw5MHtaUizLATxANw_ZdLkP1TpSBR3QLaS3riecXmqsIbM42JavTjWaSevzBvJ8gyJZyM5408cb1LXjbLl9pl6eHdmlFvBX56NBI5Bm_JR38niCOTkMJU4JOCFbpTlJmqZSUaVkaN90TVFHEDDsasMqbJSHL1eKXNfdgz5ppbxZhs2K2B9uKcazxc6YpwYk9oIxvR4IVFqiV-Jln8x2rVkVUwBcaR8uz_-AUzezzPaGoM1fC5fbgSGSVGXe2m0d9uYtm4A5jO4vjs54JjqZxXGuxzWrtRIYYCViACNoBGi-WgY6Q4XLouADe_eciVKr6brTHfCvMwFN2TFc3MUi9NqmNHSX-l59t1ZLugZ8H4D3eaTf9OkfUtwsLMeWrwYTCV1vFoi0o0-2pUmoiC_4NSpJGrVYj0ehaH91FHBuYu5EZ8Eqd-FgPlt4Zb8us49U0ZPhImiRBqS6aCOT56xxx3g5ZwDT3AsuhIsSg4IQdy0mkCNhXZqAcjKPrjTgVzrRMOg3pH6FEbbf6tMclTXdJBFMMp606GJ1Pm-w_YNykmqQbvYhiaHeh--OFkVZzxrHKk1hGnWNjLOow=w650-h300-no


Here's what my frame looked like after I welded the main frame tube in place. My first time wasn't correct though. I had the caster angle a bit too steep, so I had to cut the welds and re-do everything to give more negative caster. Once I had that main frame piece welded I placed the recycled seats up to give an idea of what it might like look.

toAd3HSnH0yDMK30z2ckFc6SzZ_kIU1AtsffWngBORd0h5KAG3TxAfs4zevyRzaxip5_nJj_XakK-gPDL4q5aZV6Cd95-qLk3BsHz3NktB44ZAKwyIEucYrcqUSx0RWz2WPvlYVKjROUnK475-cUso_zJSpp-tXwNjZkWKT9FMQG4qd9LKqnd6wyWC-cNRK_x88F1bBRuME_hdADJHNvah6CUUpogt2TJPCqz_RZoRs4aDTyss0P0I5yd_DXYIj2kYQ83hYDVQRbaBT8-7Z4HCzIlFkShISEdzldpd3e0hApZc6cKrntNRITlvKP7uMBfoW_XvJ3Hze-ZPVV9rwdMOAAeC-6DZh-sFM_NmopjzFIK8SsWLkeS7F-1u-C-ZasOLmK8Hu_zfnkVGqi8B5vbaRKoXqc1gUAzoSQlPurLzo1a0q740OG7Ay7wbPjffY_AhnABLfGlHZdsx9MFqlhxjqtXedG02ik7v70QVqHAPrIB4NFCz1ll2kw2fLw3WjdvB0MWDiid2I9BK83q2enje6PXD4FZwItEIPLjDifRcgEKfLQu9-1C1krzBDrpew_NPlCNQ3ypohhxcuNUZFPvwIrXNZKsU7qUqi_BWUE-_otNa4Zki_VuIOc9CjkgQoLcj66RCuTQW9iKGwxRndPyhojbAY2QfTkFOESqbF9R0p3CE4cvSk9-cO404sGaW98pQA09fuNKIWEmCGiTC3BS-MqNg=w1070-h802-no
 
Putting the seats up and also consulting with some crude drawings I'd done a few months ago told me about approximately how long this contraption needed to be. The next step was to fashion some chain stays. It was here I needed to relocate across the neighborhood to a friend's garage/shop where I would have the space (and reliable wiring), to support all the welding and grinding I'd need to do for this project.

The chainstays were started in my former workspace and finished up at the friend's shop where everything is being done from here on out. This is looking down on the chainstay assembly from above. This was before I had to re-do the cross-piece. Some unaccounted-for metal flexing meant I didn't have a completely straight assembly. On a regular bike frame that area could be cold-set, but let's just get that out of the way here. No one is cold-setting 1 1/2" square tubing joints without some serious force - more force than I have at my disposal. So, I cut off the cross-piece and welded in an new section, keeping everything more securely clamped to prevent heat distortion from the welding.

9QEcc5i3dUj5YHXA06nKe5zmmbofXdlZJLDPs7YORlXUcvoR7fk-z0qeGzXXEwf92N_fl07qRsrfF2O65hkB36luk0m-5ZC1RocrE9RWsD1ICLc6dwzsMVBeRWJEq8-blo7NMs40XTzjOCk9_56B3ny0VFeRZ-PuYPOLLuR6hCuqdmge0vB5tMcQRNrny1ZTPoySuqIKNlyywYlfKvBX--4v6ujIRuWq79wKxYtQIFJ0kz149ib0bC3gtbtmp9M2XdJUCb_JIkPS9ak4JLpVcnyEJGm-qv-bJx0PKfcgQ6JyE0m9aTTleWFW-9QhuxnhtVHHxf312SMV7iau_3SJmzKbqT-D4Bf0_G9jhiSd85rgMzpNcfqprbSUAbgDLLElaBia5zW-UCf9Cx4RKGHxBgN9pHuQMOHy6okbrNQRsRkKhohVZsaBZu1jba2HEZcWX9OaVNZBTZse2eNk4zRX14h73ALe31OgyOL3kBXtXmX6ctEV4p6TNh9EErrZOgMhqsgXvEYMzlFXkkCorLPdsgQUmvhLvCcuW12OBXFH5jGeQBlp_-ixXwTgdFvXeFXlqrZO8fJvcQ4hAy5e_YR8Jr4ttDgNbg8RDKC2kEKnaq2dx68J8l7jhkWLHciYfDX4GeclWr-QASzU-t7cW2T1bdUjM0ifmsP-WJI0TWL5TrpIxQWSjGgKDr8KmEV3rwoRNxaUwproD8XoAjikAwduerhXIQ=w602-h802-no


Here's a close-up of the dropouts. I used bolt-on replaceable dropouts, especially since this can potentially go off-road. I wanted to be able to easily replace broken/bent dropouts. My preference had actually been for an internally geared hub, but the only thing that would work with the 170mm spacing I'd chosen was the Rohloff, and of course, WAY out of budget. So, I chose a derailleur drivetrain, which also makes swapping in different wheels much easier and FAR less expensive than two wheelsets based around two Rohloff hubs! That's a Microshift 11-46 9 speed cassette that'll be paired with a 2x front derailleur and a Bafang BBSHD 1000w motor in the captain's position. The hub is a symmetrical 170mm Carver fatbike hub.

kg9490BkJ04MbO7LMQlQDL5AUOXmJGDw6BK-IhafhhEHVBlzyfPumD7m_2LiXZT7KtCXxdJ9mLhdWxAXyEXtDqPZq16-eKBRSSRoHn6yx1K4t2dSLx9LEP51gW90e53s2HSg7A7lU_C2pzAQ8IJDIib8aKjbgxATLjKWi6jxhyHsxwkqUcCTLLTwWFoTziaeYlRsVHt7BKxDSJq2X8P337ldQRNZdLOAKmTn3gMM49LmvxRphLB7iQoW_eo2YMlGj8shAviIxm5BJRLUP1NkuWuKcurUbNpadL1oQKv7hgmy_UuWNpZ778Kb2yvOz4FB_qsYt009LciD2OEaTKolT5CMEU7B4IndJFvyARmiwAiBa-2-8veK0hDgRUcfp8c0-xFgRuGZBWVaW-b6qwphCGLxsn_Z3Nz97elOlhO88kTi5JTPWYIbeFqOYxRjT8t0RtUpSj5tDbBbqKuhUXAhaqk54COez_vbxsORlbqDtAYg8eD_hgaiEOr5d0C00ku_2WYqMfywNcfA2GGGRWPNEnppYdUvJxt_1pp-JISBmsT-nYf8LJ9YaPrqlrImUxy-w7epZoLf0y4phPpDTLVl7q3Y-Qf5jKE8UvjdKsUBkLLK6OWpoIGlU8fpnRXcx6j-ncOPpV-FEcJ6uHoq2X2fX4VPD9uiZY0abhEOkPH9P2DvCDr8y5I6UhWyBVzzMcLzvVai1imivGXw_dy0x8BjVi0vfg=w602-h802-no


Here's the final result installing the rear wheel chainstay assembly. I chose to weld on a gusset to strengthen the joint between chainstays and crosspiece, and I also intend to put another gusset strengthening the joint between the cross-piece and the main frame.

XfQQBIrP-EvKNbtS_HTBte9P_i4LOdhrpjErpL0OVLydfIY3SxJljau-v_Cj_jnqoki18OllGELLn847pJ8ovAIkZcN5saVFd6THL2FhHYQ1riLMti-lbfIN-KNENhn5XgXF9hi7h8usVRpnzisUrVpzBJV9pfUnkbM7InpFY2GPh8HJRc61GjcuqbJTbeSk808E3LOK__zG7j3c9Sam0uN4wAI87UPzetcMyjEJl4gH2QfwViKKJcCttf4XAQSnH_hSU8X85MIuOT1o-PE5BWg3WeqvqpYeXBAQneNAS35NzajWf8CJvu5npVwSBarpt7m0lN16k7exo7TGGS4rmSYqNJPGD5BfX4sq7CPWDIk5otsvjuTSXq_5-X1g8KOICIc66EqCvt5bUcKONPgJ6ee6GaXUdGtd18BK0rZ8l91w8T05QeDlaiVbPiQVwHJXwotB9iqtxkQsiv3kFq3eF3Jd_75oOYRb8E2OMj1hdN5f4ShO1fQazLQM4ysuUMZAbZfLS52HWlMb_ZTZxHJc6ogYL4IFiaZELuLz1HsYHVigKzYz3rUXoueQHmuO9MDktWVGpdbdnjoU2Xv3hJpZ66TcbzzhsNi7YSA1DjH6kpN185umTIITR7yilk3DCKllWRVX3iIJeYpmsMB0LfFPS4LuHiyfquuEPLU1BAuP8AjMZPBAxfqyKF1rc_f1SJ__eSFyV9CxDujRXg5iZHYyvrc8LQ=w602-h802-no
 
The farthest I've gotten is welding in the lower main frame member, which projects out front. The captain's crankset and BBSHD motor will be mounted on an adjustable assembly that I can hopefully accommodate different X-seam captains as well as raise the height of the crankset up or down to find the best pedaling position. I've initially chosen to go for a bottom bracket height about level with the seat and minimal recline to the seats. At this point, manhandling the frame around caused both 3D-printed axles to break. They're not very durable, which is why the frame is now supported on jackstands until I can take delivery of the custom-machined axles. Hopefully those will arrive in a week or so.

ECT2kzsaOBFiBkngmOIS2T8zgA6chwToQ6rAkZCN6lvDbs4815Bja3cOQ_VUwHc4w9NNuD-0eRvc43rlyh9uZ_UI_WEYlg_FchLaDbnVbpTokHNF8jk1JQ7_9AP6Fw_9hmRSOpXZMEX3ctWDPZ8I7NFkdaji7yuZFFoMifta6OSAryNQNAiK109o2pG7bplNG3bFuFgu5IUZZ8B7PqivurpOhvDUpQxymrixa-h-6oUF6fIw37UlnWc3ARElWiTUfo_Ry7qZgIyhNN4WcinedqgPVRjUK6IPC66quzH_JrLrMUrpxBbdpSl2gSQtHB_nmdfcaWRXNOasibFCEqHARvUmhaMhE0tqa0ra1aKluCG57QzxnN687MUcT6QWYq_toRL2EffCwLCnCZkgfzVer1MLy0Rdl9t8mCo6QO-MmB0d_60ykKibGOQyZPUTZdc9VHGG2YbLs_IbmdgY0yuyC5zpiOzQVrVGzjpW-aWwMo4mh-lpQoCYV9z4Y5IoU-EHL3GMNH4NyzUIMEK0k08M2MmLqf-T3ntG8J5daP4EJsSKYTopJO9wWEgElMxE4lCcQCzVRGKXGufnbFU4J2kcikIlQLpMXbm1-MdJfNo-igomaG-r5je1fNWTYDg4HZtvvqcSn0nJDfK-qita9ZWzKDYFmjw9A5XxJ4wfo3Vu_5DhSbL1kWz0I66CgjyzMXh5PXV7mV-Q-i1QUmxRS-s7QPjYbA=w602-h802-no


Low down, this angle just makes the whole thing look a bit more crazy/over-the-top!

5iGc8YbRVN9lWDpWI6XtL7hxOe1fAK5d7eQFBe_sxadC3tccazc5z1lxK3voWIA2LN2FNsHsSvxHxOq5VJ23wvzWjiHrpLqFEScvMVLWFlZT5KJW04aSPOetjmIgdGeSSox8WgPJXG2Yn3g6FCxwsMTH4o8U7lDanSw8bVb0dmkk8wQ_pOCu30ao4ZRzqVt5676L9nN2g1RzqW-ZOEo8aRK5GEHlQQ8oRIBQlNOZ7tBzr4fT5DN4HQgy8RAntC0nS7KLVlXSLM-qBEhfq_hDac2cFpjPt0yQJTOHK7totiqRgPr_VNVPWeC03y7K-USD2P0jVIi7fMtXPmATP8QIrw4O72Fa3y58UK4FDwjdSmUEqGQT3Clq3SW1HQltoK2AnMHUqyMjvrGkFtVsdz5fA5VBOlzFA1IBtADiD7PpGCM0fbYXRKQpCeyVIN6PgN0qUKt7IfmVy_6G-6_mS3EdDW6XsdFj-GUJPE6Z08mNHOK2IXCVe8BenE33WeTSYv2Cy_ErCCiqKAu9BToAHgFrfMReyB7WpQsl_IjwDyBKCSWQtHKNomyVuXDQmytfEVeqv09MTc3aSuATiF75PWdus4IQtNaYtY6KslKwGvfKvAs0goWlOCjkVIRNB2sYitJUCB0h2ibj1FsYap0q91OhfYACGPXcS1xoCIV39zpgdfd6aUo_-Qu38NucxY1HHpeLfUjZh64vAzmyHdlUke8nbMCjbw=w602-h802-no
 
I think sharing was off on my Google photos account. If people weren't able to see photos, that should be rectified now. PLEASE post below if you're not able to see the photos.
 
If you attach the pics directly to the post, using the attachments tab, then not only will anyone that can see the post be able to see the images, but they'll also be kept with the post regardless of what google decides to do with the service you're using for them--they've dumped more than one of their services and sites before...if that one goes away, so do all the pics, making the build log significantly less useful than it would be with them. ;)


I am interested in seeing how this turns out.

FWIW, I would have gone for a lower-to-the-ground frame, for a lower overall COG, but that's a tradeoff for visibility, too.
 
Those were both things I considered. I've owned a recumbent before and wanted to have something with slightly higher ground clearance, but also my wife is going to be the primary "stoker" and she doesn't do well with getting up from sitting on something at a low height like many recumbent trikes. The full-fat wheels were chosen for several reasons altogether - higher seating = seeing and being seen better/better ground clearance for some off-road riding (although terrain is limited due to maneuverability because - long-as-hell)/easier to get on and off of. The trade-off definitely is the higher center of gravity, but that's unlikely to be a major issue except in off-road situations.
 
The next thing I worked on a few days ago was the seat mounts. If only I'd have designed this whole rig in something like Fusion 360 I'd have been able to just follow a plan, but instead I need to do one thing to figure out another thing. Often these steps get supplanted when I realize Plan A is not going to work and I default to Plan B or in some cases Plan C. In this case, the sliding mount for the seats was overcomplicated and I decided to go with a simpler plan. The original plan was to make use of the tabs already present on the Whiz Wheelz seat frames but I decided that was too limiting and I didn't like how much extra height it added to the seat mounts.

ACtC-3fsCLDR20YbRc6H8x3K0W1Qd_aE7L2Ti0wIW7d3PlWaMo_mywXEALDLhfm3RGJepStSd6BYUnr1K7ufUCO7YXHXE3eJF5Jjd4sWxqyZlLLVccQUmslZBdfWKEVEUkg-wtN4Gv7ssN7mII4RX34wN5CK5A=w469-h625-no


Instead, I drew up a few different ideas and finally decided to go with U-bolts which high-density plastic inserts (450 lb. weight limit!) to hold the main crossmember support of the seats. However, this introduced some problems as well. I had to grind off the tabs on the Whiz Wheelz seats and frankly, now I'm concerned that I weakened those crossmembers by all the grinding and heat generated. I pressed on though, because I needed to securely mount the seats to determine where the stoker's part of the drivetrain would sit as well as the captain's drivetrain.

ACtC-3fCwTZdbITB0oOsVDL2oKiMiW_7wmmOHbjJOgsQEzEom_cEj1Os2wZvVk9siXQpJgX4qfq1rVG2NgvpAmcKJZAbrkM7iSt0hYu3AjQWj7pUCydRzkUlktYpifA7MBnEdcw0Dvo6NcFhH_ANqUdxOBB5fw=w469-h625-no


The mounts I ended up devising still aren't what I want for the end product though. They'll serve for mocking things up but I'm going to change them to a third design - essentially the Plan C/Version 3.0 at this point. Anyway, the current design though flawed at least allows me to plan out and fabricate the next steps - ie. the drivetrain component mounts.

I also prematurely welded on a seatstay support for the captain's seat. This would come back to bite me a day later when I found out the stoker's crankset would interfere with this mount. I had to remove it and grind everything flat before I could work on the drivetrain mounts.

ACtC-3ciEcvWAWTIei3VsW9lVqLbJ2NByqt9eCyAPgcKVXopq0BX3TTSsy0mXwMOyHfmyLPmfXxxD3JYuD0-wiEAJ2g-PVOFGH1tLmogBTJ9PVf-MHkEnZBpyE0gz5eqyUuyJA7AUg7zKf4brKU4m9Cf_ZlaxQ=w469-h625-no
 
Now that I had the stoker's seat mounted, I could figure out where the stoker's part of the drivetrain could be mounted. The idea here was to move it as close to the back of the captain's seat as possible to allow someone my height (6' 1") to sit in the stoker position, even though the primary stoker will be my wife who is considerably shorter (5' 7"). The idea is that the stoker seat can be moved forward to accommodate different x-seams while in the captain's position the crankset (motor mount), will slide back towards the captain's seat which will only adjust in terms of seat angle.

I used a 100mm bottom bracket I had on hand to mock things up, though the intention is to use a 73mm bottom bracket shell for both the stoker crankset and the captain's crankset. This is an independent drive though, so the stoker cranks drive an intermediate unit that has a freewheel on the left side and a outboard timing gear along with a 2x set of chainrings on the right side. This is the same unit that DaVinci Tandems uses on their two-wheeled tandems, including their e-assist models. I consulted with them and they machined a one-off unit for me. It was... more than I expected cost-wise. Had I known *exactly* how much the unit would cost me, I would've attempted to figure out a different, much cheaper solution.

Still, this was intended to be used as a cargo hauler as well when the stoker seat is removed, so I didn't want to have to contend with cranks spinning in the middle of where I need to install a cargo deck. Anyway, I did see some much more janky solutions to having an independent drive for the stoker, so I think it was well-worth the added expense to have a professionally-machined unit to install, especially one that the fabricator assured me would easily withstand the e-assist and even would hold up under extended periods of free-wheeling without load being put on the middle part of the drivetrain. Having a freewheeling middle portion of the drivetrain was something that folks on the ebike forum told me would NOT hold up to extended periods of time of freewheeling. I trust the folks who make tandems with this design though.

ACtC-3cuVv-dCpO38uL5hvftQkjLvnA0vdAhBJlQJ9yLiLFPcmm_meEMmV-qUSflRwLYEZM9SqC7Ks0t31r8_uRHCnCZXIyL1UwA2CHKFVh9599nZEpJOW5TlyP1xmGM9nTaDEVv7ob9AD4QTWpJYfAbrXIjlQ=w469-h625-no


With everything mocked up I could see where to position everything. This also immediately made me aware that the Whiz Wheelz seats wouldn't be the best choice for this trike. There's no lumbar support and they're clearly made for a much more laid-back seat angle. The lack of thigh/posterior support was obvious, especially when sitting at rest with my feet off the pedals.

ACtC-3c8KTXGJRm48d9K0Ei0FYatwC0_a-lIA3Y2u-8nh2m-T6DPEfgL-ItT2ktnnKO26RDi5OmV5bBikhc9RZPx5YsEtDSOXDB1Kf_6zFNb8XJrSIb2dl_p6C-ZbwI_9Ngg2KVNi-UtsHYNvgTAaXe0AAXOJA=w469-h625-no


One step forward, two steps back. So, I had to grind off that captain's seat stay mount in order to accommodate the stoker's part of the drivetrain. Also, given how expensive the freewheeling independent stoker drivetrain was, I decided to make the whole unit removeable in case at some point I redesign this whole frame. A future version of trike will probably be aluminum-framed to save on weight, so I wanted to be able to relocate this expensive drive unit.

I've been welding this entire frame using a MIG welder. My previous experience has been with oxy-acetylene brazing, and flux-core wire welding. MIG gives me more control than flux-core welding and is more tolerant of inexact fitting pieces than brazing. However, MIG welding is still not the best technique, especially for delicate components like 4130 cro-moly bottom bracket shells. Anyway, I made a mistake on the first BB shell I welded and heat ate through and destroyed the threads inside. If I had access to a bottom bracket shell threading tool I might've been able to save this, but instead I just cut the whole thing off and started with a new piece of square tubing, changed a few parameters and was more successful with my Version 2.0.

ACtC-3e2r2zYu_gl0pZ5Nnnwok0febKgSzhhs7xZTFZJW91KZTgjdPlhFb-vW4btJVpyHztI6KLX0RlsN5y5O2mJk5v3KJxJ7XVWKggYAHeIXRagYBiZfZQ9UEO3hpRfhDPsdT2Rv3ElD8ZbnkXl90hnlYQp5Q=w469-h625-no


My welding certainly isn't going to win me any prizes on appearance, but at least least I know everything is secure and I didn't have any excess-heat-related mishaps this time. I still need to drill some holes through the lower portion so the entire unit can be tightened to the frame. I need to be VERY careful drilling those holes that will accommodate the anchoring bolts though, as a mess-up here will be a LOT harder to fix. This is a further limitation. If I'd designed all this on computer beforehand I could've used a precision cutting service to get all these various plates drilled precisely. Next time for sure.

ACtC-3dLOI5ybWbWsG2vU-kCCCML9TANixac4zE7Y_uX5vioK1hbKJvL_gr9liOJeFdy1dWZp29HzLKcadF5PrAm89hJ7nNNpXPmP48iLGvkaYFuA4HDCr5IwAVQqgbpGcS3X6Jr9_a5NJEJ5c9dXxs3qpPJWw=w469-h625-no


I also finally got the captain's seat mounted, but one thing I realized on seat mount Version 2.0 was that the top plate where the U-bolts are, needs to be wider. I likely won't be keeping this design though. I think I'm going to go with Version 3.0 which involves sandwiching the lower seat crossmember between pieces of delrin plastic and having that whole assembly clamped around the upper main frame member. The use of delrin will also make the seat mount more kind to the frame paint than the steel mount.

Also, I realized a couple days earlier that those Whiz Wheelz seats weren't going to cut it and would need to be replaced with something else. One major issue, is that seats are old and all of the plastic buckles that tension the cover have gotten weakened and as I reinstalled the cover many of the buckles broke. I could probably install new buckles but it's problematic given that they're sewn into the mesh cover and not easily replaced. Also, why go to all that trouble when the seats aren't great for this fairly-upright riding position anyway?

The current plan, since I'm under a time constraint on getting this entire trike built/painted by the middle of the first week of May, is to buy ready-made seats from A. D. Carson of Recycled Recumbents. Sure, I could download the Barnett-Williams seat plan he has on his site and make them myself, but I'm afraid it would take too much extra time. At my current pace I should be able to have the trike rideable in about another week I hope, followed by some test rides. If the test rides don't reveal any major weaknesses/issues I can move on to finish painting and even though I won't have my friend's shop available I can still fabricate the new seat mounts based on the ADC seats and install those at a later date.

ACtC-3fLe8RaU98p8nzzOHt2l06TUm2wgGVRUgX2OYB4qYCAC-z1XSxx5PADSOO6fWLRDYJg9hx1v3crwNMPrFlFYzxZRyEN_72IcCqTMeHy9_r1kb02JvFyR1dx91CmHtBUp5qPrmf4eUVQyYVv8s2LPksC8Q=w469-h625-no
 
kiltedcelt said:
If only I'd have designed this whole rig in something like Fusion 360 I'd have been able to just follow a plan, but instead I need to do one thing to figure out another thing. Often these steps get supplanted when I realize Plan A is not going to work and I default to Plan B or in some cases Plan C.
This is usually how I build my stuff, partly because I don't always have all the parts needed to do what I really want when I start, but if I wait till I have evertyhing I'll never build anything. :lol: Some of my "doing a thing to figure out a thing" goes on over several years...or never stops (as in the case of SB Cruiser and CrazyBike2, for instance).


Instead, I drew up a few different ideas and finally decided to go with U-bolts which high-density plastic inserts (450 lb. weight limit!) to hold the main crossmember support of the seats.
Thank you for posting this--this is a much better mount than what I was about to do on the new Cloudwalker Cargo Bike (formerly CrazyBike2), as I am rebuilding it using the existing frame (mostly), but need to move the seat but make it adjustable, and I think the U-bolt / plate method you have there is almost exactly what I can use for a slightly adjustable seat position (since I wont' know what works best until I try it, and cutting/rewelding it a bunch of times would suck. ;)

BTW, if the grinding didn't remove crossmember material, then I wouldn't worry about the heat--I've ground on stuff up to red heat, even on stress-concentration areas, and never had a failure from that. (from grinding into wall thickness of a tube too far, sure, but not from the grinding heat). While it's possible...unless it started out right at the edge of usability, it is probably not a problem.
 
amberwolf - well, the Whiz Wheelz seats aren't quite the best geometry so I was going to follow a seat plan that a guy on the recumbent message board suggested, but even after printing out his templates I only succeeded in ruining a piece and a half of 1/2 EMT conduit, so I scrapped the idea of making new seats. Of course, keeping the Whiz Wheelz seats is also seriously problematic because the rear back support seat stays are welded to the aluminum frame in an asymmetrical manner which is extremely aggravating to me. For now I'm making do with what I've got and trying to bodge something together to make the captain's seat attachment secure enough. I had an idea yesterday while doing some work that maybe I'd design a mount in Fusion 360 that would work with the asymmetrical mounting tabs, and then maybe see about having it 3D printed in steel by Shapeways. I have two 3D printers myself, but they're not capable of printing with the metal filaments. It's possibly I could design something to be printed entirely from plastic to support the back of the captain's seat. I'd probably print in PETG because it's UV stable and stronger in many respects than ABS without the headaches associated with trying to print ABS (warping prints, toxic fumes, etc).

As for those seat mounts, I've gone back and forth a few times about exactly how I was going to build them. The initial mount design with the U-bolts was problematic because the top plate wasn't wide enough. It would be okay with a wider plate, but I also had an idea to create a sandwich of high density plastic around the lower seat support and attach that to the frame with bolts of some sort. The idea would be to have a low friction, paint-friendly mount that wouldn't necessitate a bunch more welding and trying to drill holes that for whatever reason, inevitably DON'T line up properly. Most recently, I decided that the current mount design was probably the best and easiest if only the top plate was an inch or so wider. So, I ordered another piece of suitable steel to use for that, so I guess I've gone back around to a modified version of the original design. I've still got the 3/4" thick HDPE though in case I decide to make mounts with that instead.
 
kiltedcelt said:
amberwolf - well, the Whiz Wheelz seats aren't quite the best geometry so I was going to follow a seat plan that a guy on the recumbent message board suggested, but even after printing out his templates I only succeeded in ruining a piece and a half of 1/2 EMT conduit, so I scrapped the idea of making new seats.

Since I didn't have a bender, but did have steel tubing in various stuff that already had bends, I made the old CrazyBike2 seat out of that (specifically, a bedside potty), cutting and welding them together, with bits of smaller straight tubing inserted into the butt splices for extra strength. It was more difficult to lace the webbing around, but I also wasn't using the usual webbing--it was some of that nylon stuff you put overhead for shading patios and such, which at teh time I just used a soldering iron and melted holes thru the layers insteaed of using grommets (later I redid it using grommets, and that's still on there today). Used paracord to lace it up tight across the back. It's not as good a seat as one that's fully bent in all the right places, but it does work. Being steel, it's heavier than it could be, but the whole bike is not light so not a lot of difference for a 2wd hubmotored cargo bike. :)


Nowadays, if i had a tube bender, I'd build a new seat for the Cloudwalker version, made much more custom-shaped for my body out of EMT or whatever I've got laying around, and probably get some canvas to custom-make a shaped laceable cover for it.

However...for the SB Cruiser I found what has been a near-perfect premade solution: the Stadium Chair (SC-1).
https://www.stadiumchair.com/
The first one came from goodwill for a few bucks, and it lasted at least a couple years before I wore thru the canvas bottom where it passes over the rightside top rail (getting on and off the trike mostly on that side, sliding across that part). Their new version "gamechanger" is not quite as suited as the original because of the tubular rails that stick out in front, but those can be cut off and reshaped, or the old version is available from various places (though beware a number are counterfeits and are made MUCH more cheaply out of thinner tubing, etc). There are wide and "regular" narrow versions; I have the narrow one and it has worked fine on SB Cruiser; I think I would use the wide one on Cloudwalker.

For SB Cruiser, it has a flat-topped large box for cargo and stuff under the seat, so mounting the seat was as simple as drilling two holes in each side rail, and bolting the seat to the box. Using one on yours or on the Cloudwalker would require bolting or welding a couple of transverse crossrails under those side rails, and then attaching those to the main frame of the bike. Shaping the rails would make it possible to mount the seat non-horizontally, as well, if necessary.





Of course, keeping the Whiz Wheelz seats is also seriously problematic because the rear back support seat stays are welded to the aluminum frame in an asymmetrical manner which is extremely aggravating to me. For now I'm making do with what I've got and trying to bodge something together to make the captain's seat attachment secure enough.
I didn't find enough images online to see quite how the mounts are made. I can see them in the pics in your most recent post, but am not sure that I am seeing them completely/correctly. Is the asymmetry that the left one is longer than the right? Or are they at different angles making them appear different lengths? Or both? It is odd that they did them that way--were they designed around someting on one of their trikes that required that?

I'm just asking because if I can "see" how they are made, and can see what you need to do with the trike, I might be able to come up with an idea of how to do what you need to do with them.


trying to drill holes that for whatever reason, inevitably DON'T line up properly.
For that, I would recommend placing parts in position, clamping them to each other, then drilling the holes (for bolts, etc) thru both (or all) parts at the same time. This won't work for certain mounting holes, but it does work for most bolt holes.
 
Amberwolf - thanks for the input on alternative seating arrangements. At this point (as previously mentioned), I'm determined to use the Whiz Wheelz seats unless there ends up being something horribly, ergonomically-wrong with them, or there is some other unforseen mechanical failure. The asymmetry I refer to is those tabs that project out the back of the upper part of the seat. The on the right (non-drive side), is almost 1" further off center compared to the other. On the rear seat it's not as much of an issue because the telescoping stays (that came with the seats), extend out long enough that the one that's farther over isn't flexed out of line that badly. I still don't like it, but I kind of have an idea for how to compensate for this asymmetry on the captain's seat and the same thing may work for the stoker's seat as well. Mainly, I'm thinking of enlarging the holes in the tabs from M4 bolts to M6 and threading them into a steel tube of probably 10mm diameter. That steel tube can then have some tabs welded to it asymmetrically so the tube will still engage with both tabs on the back of the seat, but then I can have an attachment point to the frame of the trike that *can* be symmetrical and close enough in to avoid interference with the stoker crankset.

Another thing comes to mind about the seats - given that bending tubing can be such a pain in the ass, it just occurred to me that I can probably 3D print some lugs out of high-strength PETG and simply press-fit straight sections of tubing into the lugs. There are already some traditional bike frames that have been made with 3D printed lugs and utilized carbon fiber tubes or other material. One need only epoxy the tubes into the lugs, or engineer-in some kind of set-screw type of fastening. This could theoretically allow for a number of different seat geometries and with some of the lugs potentially being made two-part adjustable it might even allow for better tailoring fit for lumbar support and the like. I'll have to examine that avenue and talk with some other 3D printing folks and ask if they have suggestions on how to engineer the design of the seat tubing lugs for strength and to also eliminate or greatly reduce delamination along print layer lines as can happen with some designs. I'm already going to have to 3D print an armature for mounting the BBSHD display in a better, more ergonomic manner so I might as well add in designing seat lugs to my workload.
 
Lots of significant progress over the last week or so. After mocking up the mount for the captain's seat I was able to sit down and begin to figure out where the captain's crankset/mid-drive motor would mount. Although, I guess if we realize the motor is out in front is it really a "mid-drive" anymore? Semantics I guess. Maybe these types of motors should be called "bottom bracket motors" instead of mid-drives? Anyway, I used about every clamp available to figure out about where the crankset/motor should sit. I also intended to make the boom adjustable, but right now, figuring out what to do with the excess chain is overly complicated and for the time being the captain's seat will be only for riders with similar X-seam to my own - ie. someone 6+ feet tall. I hope to build a chain-manager at some point and make it something easily clamped in place.

ACtC-3crAM3Dg_lP_20XjSxhT5WuGUfteVEGyzzcPN9a8TzDME333ihkD_HtQL-wHSuFNnMmHtKArmZVxJwLTFN8G-v6EwwYvJYQAbb3Q2DtslkxUrxkRD_VosvctaCNdsFya3KU7XIDSs-_P6JUQeuAXQk3SA=w834-h625-no


Here's me crudely figuring out leg extension. Even with so many clamps, the motor still wants to move around. Also, the Bafang motors have a portion on them that is kind of flat and I thought I'd try to make use of that to make the motor rest on part of the frame. Hopefully it will simplify some aspects of the installation of the motor.

ACtC-3csdS_JCUzCs2aOPXPbnPPKaXlcDgNhdoqcGl13mBTC03uvPdYTrPHtuVxm3Gf7DHJzTdMBygg-WfNQKBeEpKEvrHFtxBdA8bQ06QNydMLxyspv04de0yj5wXoXWNhAItN7nrtKB2c6ZHWeI47USRsDoQ=w469-h625-no


Here is the motor mounted to the adjustable boom. The boom is able to travel 9 inches backwards, so in theory I should be able to accommodate a pretty short X-seam captain. Still, that chain manager for taking up that extra slack is an engineering/fabrication problem for a later date. The goal at this point is simply to get the trike rideable and I can design and build refinements later on.

ACtC-3cvqe5N85-jO9iLhhpB8Yqiu-lLnlBNSXw_eoXMxHg_gz2J6FufYzJ_7V-70RESOUS1-7VCHy6g7d0eGQDzbrg0D6Ew9tHOp5riropYJsRR5iBGFbIongjumMnEj52EvTXAM1vblhrpyEQcKLxUHpBiPA=w469-h625-no


And a view with some bodge-together temporary axles holding the wheels in place. Another maker-person I know agreed to custom machine some axles for me, but it's been slow-going. Her metal lathe tooling wasn't initially up to the task and the preliminary version of the axles she sent will fit the wheel hubs, but are too fat to interface with the kingpins. With some additional measurements, she's currently working on Version 2.0 of the axles. Hopefully they'll be done in time for the test ride.

ACtC-3eikvZwI7WNDiFOzSR_gmOvbqAv4gknBcGomcZIUFiQp6y84SBuaAXb7roKX73Tgmu_UsDZb5zYsJliKBdqcj_sohtLyRwNqKQzspdfG8BP0uToVCAKG1foU9S6FXw9OAYi4V4loEs8UJaSpUKC2FUgow=w834-h625-no
 
The next major thing I needed to tackle, if for no other reason than making the trike easier to move in the shop, was finally figuring out the Ackermann Compensation for the steering and linking both kingpins. I used a piece of nylon twine to run a line from the kingpin back to the center point of the rear axle to figure out where the Heim joints of the steering linkage arm should be attached to the kingpins. It turns out that the Utah Trikes Sun EZ Tad kingpins are drilled for two separate attachment points and the more outboard of the two was pretty darn close to where I needed them to be. They ideally would've been about 6-8mm further outboard, but I think I'll just go with this for now and if for some reason I note wheel scrubbing then I have an idea of how to adapt the EZ Tad kingpins for a better Ackermann Compensation.

I bought a hollow steel tube optimally dimensioned in terms of outer diameter while also have an inside diameter that wouldn't require too much to drill and tap for the Heim joints. One Heim joint is reverse-threaded though, so I needed to purchase a special tap for that. Having both joints threaded reversed from each other means you can rotate the linkage bar forwards or backwards to dial in the toe-in/toe-out of the front wheels. You can make the bar adjustable without using reverse threading on one Heim joint but it makes it MUCH harder to perform adjustments, because one joint will always need to be detached from the kingpin before you adjust. It's just WAY easier to have one of them reverse threaded.

ACtC-3exdREQCS8rjLgo6V_GfIpOmZvnkbi_RBakZXOHeQRlZe5t5u82iqP2D2QPT0sHCP0PVFs6EdmmCIpuhaiLfv32GsPD_-orGDvpKMyH5bhMwaMzcOANKwIYWevMotl18nIB-9rl_eJxF97B1jWXN34A2Q=w469-h625-no


The completed linkage arm in use. I adjusted the toe-in by eye, but before I actually go for a test ride I'll take some more careful measurements to make sure both wheels are exactly parallel to the frame of the trike.

ACtC-3e6omX3rLelVUlFI9L40xhsQJ4A6zEx3JVDX4F_oXe_sxJr_2a4woFwcDSH2q20P3_68XWNxuCoEkTHg5i1h01tP9K3xptiFN9vROzMC7TFP1FWZfxCNdRxV8h-6mr9rLH18h9fCT_Ed3koZA8TQ5lIPQ=w834-h625-no


A view from underneath. There is some phone camera lens distortion here, so that right wheel does *not* in fact lean outwards at the exaggerated angle you're seeing here.

ACtC-3d8psUJ0lEx-VAaT3r3Hbd1R_9XtJFswlPt3cBsHAFooLTSjDkZdnALNBYp4Cc_jrn6bQHCdP8PaloIAFObemZB9F6i8xKNLgE9hf9NpTNgSe9CqJ65guOnZlomgf1XrRS6J5YwaFqBkDq9OIhMQka8_w=w834-h625-no


Although, -full disclosure- the front steering assembly of the crossmember with two head tubes, is not entirely symmetrical. Yet another casualty of building in the most crude garage-based fabrication setup with little ability to accurately apply clamps and jigs to parts before and during assembly. It would be a not-insignificant job to backtrack at this point and build a whole new front end, so I think I'll just deal with lack of symmetry. The worst thing it will cause is some uneven tire wear.

This entire project is, at this point, proof-of-concept. At some later date I would like to build a second version of this trike, with lighter materials and the like. For now though, simply achieving a rideable result with a victory, and plans for a later version will naturally grow out of experience with how this version handles and any inherent weaknesses in the overall design.
 
At this time, I also started working on chain management as well as crafting a disc mounting tab for the rear wheel. Because this is a tandem, has e-assist, and will also be designed to carry potentially heavy cargo I elected early-on to go with 203mm disc rotors on all three wheels and Magura hydraulic disc brakes. Crafting the rear disc tab took no less than three tries and quite a lot of frustration. Framebuilders typically use ready-made braze-on disc tabs or will have at their disposal highly accurate steel drilling equipment or even a CNC machine of some sort. I am essentially having to draw something crudely on a piece of metal with a Sharpie then whittling the part out with an angle grinder. I can drill a hole with the highest accuracy I can manage only to find the second hole will not match up in some manner, thus negating the last half hour of fabrication. Thus, the "Third Time's a Charm!"

ACtC-3dnTbyS0exiCABPvQl-bemTR22clG5h0Rfv5R0l1mfF6ErAasUx3H7XZ8vItSIwCHDWj4emxrFWHb7SS1GsbmijTQJakj5sbs2xCihFljXYut0RmkY04nphWbTh9Ds87e1S7Y0VkqTSW9SHiG4k6mwp3A=w469-h625-no


ACtC-3cSY3FTWi9J1ZKVDKkuOVMEJYFb_1Z6QoaBZUK4yTJ80EdVdmNNGDPAQJ78HhHEQI2ERJzNRFaaBQdGkzeDxN7NUcCSUlHSggCN0u66NidXjk1oPsyQCawnE3QxaO3YJPdahe852c-De52vvfVDP-MRxA=w834-h625-no


It was also at this point that I was beginning to struggle with getting a decent fit of the Magura calipers to the rotors. I was reasonably sure the used 2 piston, and later 4 piston calipers I tried on the rear would both need a maintenance bleed because the pistons were not retracting fully, making positioning the disc tab before welding difficult. Still I managed to get the tab welded in place and then I started messing around with the brakes for the front wheel. Without going into lengthy specifics, the dual caliper system I was using for the front even though brand-new and un-used, suffered from the same excessive need for extreme tolerance fitting. I don't remember having these issues when using Magura brakes in the past, but I ultimately decided to throw in the towel on hydraulic brakes for this project.

Though plenty of production bikes, trikes, and tandems use the venerable Avid BB7 mechanical disc brake, I have used them enough over the years to develop a largely "love/hate" relationship with them. I love that they're cheap, and not overly difficult to setup once you know the tricks, but they're difficult to keep adjusted as pads wear, they are loud, and ultimately, a brake design that works by bending a rotor via movable pad to stationary pad is just a poor design. In this case - enter the TRP Spyke/Spyre family of mechanical disc brakes.

I ran TRP Spyke disc brakes on several bikes for a few years before eventually switching to hydraulic brakes. Frankly, I always found the TRP Spyke (the Long Pull version for flat bar brake levers), to be a decent brake. Good stopping power and EXTREMELY easy to set up. Adjusting for pad wear is a breeze although I found once I started using them on e-assisted bikes that the pad consumption was greater which necessitated more regular adjustments to compensate for that increased pad wear. Anyway, I threw in the towel and hydraulics over the simplicity of mechanical disc brakes and ordered a trio of TRP Spyke calipers.

So, while I wait for my second-choice brakes to arrive, I moved on to finally addressing how to attach the seat stays on the back of the captain's seat to the frame. Most tandem trikes will have the captain's seat designed slightly differently so that it can be adequately braced with a single seat-stay that doesn't interfere with the stoker pedaling. This was further complicated by the old Whiz Wheelz seats having the seat stay mounts on the rear offset in an asymmetrical manner. I'm not sure if the original trike these seats came off of had some sort of asymmetrical rear frame, but these mounts have certainly caused me a lot of headaches trying to figure out a way to attach them and still keep the captain's seat securely braced. In the end, I think I worked out a suitable solution but not before I spent more than an hour fabricating a special bracket that I ended up *not* using. I still need to acquire some more parts to finish my revised mounting plan but I'm hopeful that the Version 2.0 mount will be secure, sturdy, and stable.

ACtC-3c5irdKYIyGBkT4cXa3-aDdxe_bHcApEiY6mcQqSwps23p4FGTFtdJGHjXd-EMTsC0mUQ8DtOn77snXCoqSR0dd5rg0jFiu7Q-8eqwav7mD0lY218Wr06R8yjsV2oyol-AOcndH5iwKxzVxaChmOv7XsQ=w469-h625-no


ACtC-3d-PqssNItchvz1MgxAfb4tm9of9vKMjstdI8jPsTb93hNtKufzfteN8N_q6HggScdxQGw3Kz0SzDyVCFG6k-cv-grgbbE5SbdVMNAMPU7zZ52G4_iI58Na02K-jeS47vOT09xIENPF8JhMqDymJseyfw=w469-h625-no
 
Finally, just one random shot from the rear when I was messing around with the rear brake mount. The last week and a half has been particularly frustrating for several reasons. Not having precision fabrication tools is severely limiting and I'm often forced to spend an inordinate amount of time fabricating something over and over again before finally getting a usable result. Also, certain things I hadn't anticipated in my earlier planning stages have meant I've had to spend a lot more money on a project that has already gone seriously over a budget I'm comfortable with. All that being said though, it *is* coming together and I think it will be rideable in a few more days, hopefully. Also, in spite of budget over-runs this is still going be significantly cheaper than any production tandem, either two or three-wheeled.

Also, even though I'd thought early-on about buying a used tandem and modifying it, I still wouldn't have been able to achieve something that could handle any off-road riding and would not have easily incorporated other features I was interested in like the yet-to-be-designed/built removable rear cargo deck. I still think this was a great exercise in fabrication and though it's certainly been frustrating, I won't deny I have learned a LOT.

ACtC-3fRrSotbEozYL2SeyxP9_bf5Z0fmvwV3pWbiVSxsP6CxH_lbStpSK5UO8uPt-p_lZ5bFxm9ffyHsekehBrjPzp8wAQRBKx1azDg86eZ8JJp8c-p56mr480qo_BVzEesfykoVwrxsDZuAGbGd2aFIe9waA=w469-h625-no
 
It has been a while since I posted progress photos, but I've been hard at work every day. Some days have been in the shop actually fabricating, while recently I've had days where I've spent a significant amount of time in front of the computer researching something - usually because of some failure of my design process where I've had to backtrack. On the plus side though, I had my first couple test rides. I had originally intended to install Magura hydraulic disc brakes but for whatever reason I thought I was having fit issues with them and decided instead to install TRP Spyke mechanical disc brakes. The Spykes are a dual piston design that is WAY easier to set up and maintain than the typical Avid BB7 mechanical that seems to get specced on virtually EVERYTHING. The BB7s have pretty decent stopping power, but they're a bear to keep adjusted and there is almost no way to not have them making those godawful turkery-gobbler-wailing sounds when applying brakes.

ACtC-3eTYaAW0EhUHlxg7tb7u6Io6f1-RPw3qj-K7952I90CBuJsY-NKNvyqzCm2WUuWxAtf03wyfix8JzR6p_bVIUmD2X8KJ6JP6UbZUDn3mZIxDyoQydL3M9GdYZkOPa_FNAzg1Bl_6tr74PGIFcucxc75qg=w834-h625-no


Anyway, I took it out for a solo rider spin and confirmed that at least in theory my construction works. There were MANY obvious kinks to be worked out though. I still didn't have a truly secure way to mount the Whiz Wheelz seats to my frame. The stoker seat was more or less okay, but due to how the tabs on the back of the seat back are asymmetrically mounted, I had to create are really ugly, bodged-up, method of strongly securing the seat supports in a way that also wouldn't interfere with the stoker pedaling motion. This took me about three tries to get right. First a bracket on the frame that later ended up being removed, a bracket to go between the tabs on the seat, and later the version I came up with. Heavy, ugly, and overbuilt, but it certainly isn't going to break.

ACtC-3d-PqssNItchvz1MgxAfb4tm9of9vKMjstdI8jPsTb93hNtKufzfteN8N_q6HggScdxQGw3Kz0SzDyVCFG6k-cv-grgbbE5SbdVMNAMPU7zZ52G4_iI58Na02K-jeS47vOT09xIENPF8JhMqDymJseyfw=w469-h625-no


ACtC-3fP634brtrbgAq_GeNardjDOpQqRBW_A0IF-f6joaKnECBI_Y-rsr8g_WEoxoV8KeMkKLE-BnNXN33VyWtgIDpB8AnZGWLc2sc_YH_QYXqn1TrFd5NjqCkUzE-sWvkfVgkoEpfe_-ntUdJM6BXJJ-22Eg=w469-h625-no


If anyone can tell me WHY the mounts on these seats are offset I'd appreciate it. I'm guessing it was something particular to the design of the frame of the Whiz Wheelz trike these seats came off of. It's my understanding the original frame was aluminum lugs and carbon fiber tubes and the front steering used a series of Heim joints to form the steering pivots. The guy I bought the seats from (for the cost of shipping), said the trikes were twitchy and felt unsafe to steer at speed and had been sitting unused for years. Perhaps the rear part of the frame was asymmetrical for some reason?

The next thing I did after that initial test ride was to fabricate better mounts for where the seats connected to the frame. I chose a U-bolt with high-density plastic insert to grab the lower seat rail and my original design had the plate those U-bolts were attached to, far too narrow. So, I cut off the side plates and welded on wider plates. Even with careful clamping and measuring, I still ended up with the holes being improperly lined up on the plate. The U-bolts fit just fine, but the sets of holes were crooked. Luckily, the plates were wide enough I could grind a little off either side to even things up. Yet another frustrating effect of having to do things that SHOULD be precise with imprecise tools. Ideally, I'd have machined those holes or at the very least been able to use a drill press. Instead I had to drill them by hand with a cordless drill, and in spite of careful measuring and using a center-punch - well, less-than-perfect. The end result though is stronger and more stable than the original version. I'll call it a win.

ACtC-3f75Lw7n359Rq6sRfrAp5aovWjYxDK162FEKSodM7C0DuHD6okJNihmf-0zEsi9iv20PTwV0B_n7a7TY7DBloyvPYLPuPV1NwJUyrd9Uw3hrSVjK2tB04qrjJA2O9w34r2gPG_QWwSRGpM2a3HnHOokZA=w469-h625-no
 
By the second test ride, with a stoker a few more things were made obvious. The un-powered gearing was all wrong on this trike. The chainring on the captain's crankset/motor and the drive chainring on the stoker's crankset were too high of a tooth count to run effectively through the free-wheeling jackshaft attachment. It utilizes a low tooth count drive wheel on the outside and a pair of re-purposed cassette rings on the inner part of the drive to create a 2x setup when run to a rear cassette hub/derailleur. Even putting the the chain on the inner (lower) gear of the 2x, we were barely able to access the about the 4 lowest gears. The higher gearing of the 9 speed cassette wasn't even available as the even higher intensity pedaling with a fit stoker (a cyclist friend), we seemed to be limited to the lower gears. Had we gotten over to a nearby multi-user path we might've been able to get enough distance and speed to get into those higher gears. However, the takeaway seemed to be that in normal, stop and go city riding you were in the lowest gears. Also, due to having to clear the 4" wide rear tire, the chain was running through some tortuous bends coming on and off the idler pulleys. These tortuous bends also seemed to generate a quite noticeable amount of friction on the pulleys that could be felt as vibrations in the pedals.

ACtC-3fnEb7wqEnk2MVqw2HVb0RgnSQB9hn_9ufbO5ho9-o-SHVuZpEbu-ThpbzZiOsIhJxJJ1Y5IvL_h4PJHcWweCIMaJOf94kIrAzPPZ8gmQkI-nJLALyyFR_tRZ7lgUw-pG5WH9xslUO-aNvWk6eZfKPnuw=w834-h625-no


I had originally wanted an internally-geared hub for this trike, but the use of a full-fat wheelset also meant that I was stuck either trying to build and offset frame like a Surly Pugsley fatbike, OR building the rear wheel around a much wider hub standard like 170mm or 190mm. I'd had a Kona fat bike with 170mm rear spacing and felt that was probably adequate for this. So, my current rear hub was built around a 170mm Carver hub with a 9 speed Microshift Advent cassette. Clearly, in order to be able to clear the sidewall of the tire and also access the lowest gears, there was no getting around tortuous bends coming off an idler pulley just forward of the rear wheel. I'd like to know how other fat trike handle this, because clearly I've done something wrong with my frame design in order to create such a stressful cross-chaining situation at the rear.

I either needed to limit the derailleur to about 5 out of 9 available gears (a complete waste of a 9 speed), OR I needed to source a geared hub. Sticking with 170mm spacing meant my only two choices were either a 36 hole 3-speed Sturmey-Archer hub (which would mean buying a completely new rear wheel rim), or buying a 32 hole 170mm spaced Rohloff hub. I salivate over the Rohloff hubs as much as the next person, but at over $1700 plus shipping, not to mention they're completely out of stock everywhere - there was just NO budget for one of those.

Conferring with some people more knowledgeable than me about geared hubs and the input of two riders and the 1000+ watt BBSHD motor, the clear choice was the discontinued NuVinci N171 Constantly Variable Transmission Hub (CVT for short). I'll skip the specifics, but basically the N171 hub is the only hub that could handle the kind of torque that the motor and two riders could put into the system. The Rohloff comes in second place, but still has nowhere near the torque-handling capability of the N171.

ACtC-3duYpBGRjbYZo62nraTifrfsmgg3_EqD0o_0g6YsUcGLv3GCxKcaCopaLgg2bzsVi1dSmns6g9-eVRy6LFH-vLm-Om8E-rFvDnOgcCBFuAPSd6kdhIHRLQs70X8fjhtfFNLaY8D_zac9eAdIsO6wOg_AQ=w469-h625-no


The N171 has gained a cult following in the e-bike DIY world over the years and even now that it's been discontinued for several years (and NuVinci has changed names to Enviolo), the N171 still gets snapped up as NOS or used to be pressed into service for high-power, high-torque e-bike builds. So, I sourced an N171, a supply of rebuild spares, and cried a little as I spent even MORE money on this money-pit of a project. Still, I guess this hub has the durability to potentially out-live this project or at the very least be the most robust drivetrain option to allow me worry-free opportunities to tinker with all the other post-construction aspects of the project like cargo-hauling, solar power, etc.
 
One thing I'd noticed late in building the frame, was that the front cross-piece with steering assembly... well, the angle on the drive-side head tube was wrong. Once I'd put the frame together and gotten the wheels installed with some temporary axles, I realized the drive-side wheel leaned outwards at the top compared to the non-drive side. Somehow in spite of careful measuring and clamping during welding, the angle of the two head tubes ended up off. I was resolved to leave it alone as any effort to change it would involve major re-fabrication or modification and I assumed the worse case scenario would be funny tire wear. Well, the first major test ride where I picked up a stoker and rode revealed that the outward-leaning angle of the wheel caused the spokes to flex in certain instances and there was so little clearance between disc caliper and spokes, that the spokes would periodically contact the disc caliper. Not good.

So, one thing I did was to correct the frame alignment issue. The easiest solution seemed to be to remove a wafer-thin section adjacent to the head tube, the close the resulting gap, thereby changing the angle of the headtube. The resulting gap would be welded over of course, and if it's one thing I've learned on this project - the MIG welds are actually stronger than the steel they hold together! So, I corrected that frame alignment issue, but then I was concerned about the proximity of the spokes to the disc calipers. A quick search online revealed that even a simpler design mechanical disc caliper like the Avid BB7 was still close to the same width as the TRP Spyke, dual piston caliper. It's difficult to get a decent picture of just how close the spokes are, but even on Avid's website they seem to indicate that even clearances of 2-3 mm between spokes and caliper are acceptable even though this is extremely tight.

ACtC-3exBgrJYfSwRddfOcF-diAvz0CLmE7EupMtKAERGzvMf22W667OQ_sfJDEG6D3taBSQwZ7_mpxgLFWZ-f-MssDkh59xXVqXiHBVrvdktr4fPoElrrvIDW-hVnt_wWh-RTGhKWwGlRFJTq_3FbUvYLN9MA=w834-h625-no


I wasn't going to get any relief switching to different calipers. The solution seemed to be to re-dish the wheels to see if I could gain a few millimeters clearance. Before I went to that trouble though, I thought I'd measure the Magura hydraulic disc calipers I already had. Sure enough, the Magura calipers were *ever-so-slightly-narrower.* I pressed on and installed the Magura hydros on the front wheels and was surprised to find my initial apprehensions were all for nothing. Even though the pad clearance *appeared* to be minimal, I was able to align the Magura calipers and there was ZERO rotor rubbing of rotor against pads. As most of the braking power appears to be on the front of this trike, clearly the Magura hydros will end up being the better choice, in spite of their complexity and some of the drawbacks to hydraulic brakes in terms of field-serviceability. I think the performance of the brakes will overrule any concerns of durability in the field or perceived inability to service them.

ACtC-3ce34AaPY5xqocmDD-wiZ1JOZ-GcaSRc3uH5HfIM_plysao-sq7O4UXXMGo7kQVIDWLunw5Ju_eKL7InRpTUEGhPFsJc3HCLPC1EYbEO_i-v5YcWKo32yfdQ-oI0SaFgZR3lN3gadb7n9cawDAHH1rjOw=w834-h625-no


The brakes themselves are rather cleverly-designed. A trials bike seller in the UK figured out how to make a viable hydraulic setup where one lever would actuate two disc calipers. In this case, they took a Magura HS33 lever which has a larger reservoir than the actual brake levers made to work with Magura disc brakes. See, the HS33 is actually designed to actuate a hydraulic RIM brake, something you don't see much these days, EXCEPT on trials bikes. So, they tested this out and found that the HS33 has the ability to drive the pistons in two regular calipers because of the larger 14mm diameter of the piston in the HS33 lever. These calipers are also different than other disc calipers from Magura in that they use a barbed fitting to connect to extremely rigid nylon brake lines which are far less supple than the typical hydraulic brake lines used for all of the other brakes in their line-up. It just makes routing the hoses a bit more fiddly because the brake lines are so much stiffer than the later-generation hydro lines.

ACtC-3d4aqNj7RUIMopAmS6eLp8YorF___07KDSBRcrGeBW5MXPJl045UzKeuUleCpPdQ_ps9dsGPZNr8rT1DqwMDdNu4sSYxzSz6JknpAXkrTuuL0FcVuVOMx_3izDlnrlgAo2-PWqlXXTQZcZeT0SDlqxgIg=w469-h625-no


The two lines are joined from the calipers with this basic Y made by Magura. No fancy proportioning valves required or anything.

ACtC-3d8raVORlzDlfSuqdMLOc0vxsLMWTD9X6VDG89VcNzF41k7yNfohbM8IpmJImMlGJTuRvtPc-bfyvS1UUBOMhLSJd88pc1hDqjDqCKF6lmUVYLvN904cwkizgEbH2upN8KZsZMIDNPX8ApHFEOGMslr_g=w469-h625-no
 
The most recent thing I've done is to add a couple diagonal braces into the front part of the frame, in addition to the correction of the angle of the drive-side headtube. The braces will strengthen the front end of the trike, but they also introduced interference with the routing of the chain from the captain's crankset/motor to the mid-drive/stoker section. Luckily I have enough idler pulley wheels, and I think I'll probably be able to *lose* one set of pulleys from the part of the chain running to the rear wheel, specifically because of the more simple chain routing I'll have with the N171 hub.

ACtC-3c2qp5wDOPZMyrSUy3O0I0sfHLPPXEfo0YAKvIKvgGnEQuiPIuBVEG7_BU5Jfr6ODhUQ0nL1H5nM_o9rrLJ9sfd_XJjHsSGMQKyzd8ZcY2WWhv0ZBAkZgSzdDutbuXnmZQ8qeEsRgDCQa5EEMdjw4EShA=w469-h625-no


Difficult to tell in this photo, but now both front wheels appear to have a slight toe-in at the top which will probably improve stability and steering ever-so-slightly. You can also see a dangling, mechanical disc caliper, as I was still sorting out the clearance issues and mounting the Maguras when I took this photo.

ACtC-3eE_ij1Zj0YqR2jvxjzL5hmbA1O3gRpSJSNFwBBMFvStk-ukJtCqfzvWwZNI9wbXBLI87TzJYR7-5EJwzt7d7PCYNYMCc3pDwujF6V9cdTijinGp-fR-J8_6pnZGUPWb8GsjLiEMp1_2hq7YYN3SB3wnQ=w469-h625-no


Finally, I decided to swap in some custom short-length crank arms instead of sticking with the longer 170mm Bafang crank arms. There are no clearance issues, and while these Andel crank arms are more offset than the Bafang cranks, that's fine with me because my knees and hips actually appreciate a slightly wider Q-factor anyway. I guess it's also well-known among the Bentrider set that the smaller circles you pedal in with shorter cranks is also easier for the recumbent pedaling position than the typical longer crankarms. I just remember that I had a shortie set on my Bacchetta Giro 20 and liked them a lot.

ACtC-3cGoHQJQ5Sx-XKHU0ANrS0ak40vgYojDvjwoKdrkFkWmO0_lCzcpNgqgUTXIghoKIclscc9tb7OO62xUA1_hAK8cTOgLR0uTB_bMedPsd31UpSfA4QjUazSblrKEgrFd1zvaBR1L4ngeYpr4wpE0fG85A=w469-h625-no


ACtC-3cqTGfERq0BFpohu-adplaf-qNqg1L6LM8rs76l6DMqrjm4luVFnE_8N7b-aJLWU3ofWskyV2SJ0gc1YTFb_JgBKkvoc3N7uh07j9OjiOsyPvtwMqkthaUJyrqxr372JiWI79j6pAJGZ9AQXgS-aWB_Gw=w469-h625-no


Now I'm simply awaiting an order of spokes at which point I'll re-lace the rear wheel to the N171 hub. In the meantime, I'll at least be able to use the hub to layout a conversion of sorts that I'll need to weld into the existing rear wheel supports that will allow me to accommodate the narrower 135mm hub. It would be kind of nice to make it a convertible design that would allow me to go back to the 170mm hub at some point if I wanted, but I don't know of a good, secure way of doing that. Honestly, I just think sticking with 135mm hubs and working around that metric will be easier to design, and who knows - at some point maybe I'll be able to afford a Rohloff and I can always give that a whirl. It still wouldn't have the torque-handling capability of the N171 though.
 
kiltedcelt said:
I wasn't going to get any relief switching to different calipers. The solution seemed to be to re-dish the wheels to see if I could gain a few millimeters clearance.

You've been busy!

Sounds like the Maguras solve the clearance problem, but could you possibly relace the spokes so the J-bends all come out on the inside of the flange? It's a pain but I had to do that to make clearance for my 12 speed cassette.

I too initially planned to build a Rohloff into my ebike, but when I did a detailed comparison its advantages couldn't justify the extra expense and weight. Plus of course it's not compatible with a rear hub motor, which is way preferable to a front hub for the hilly dirt roads I ride occasionally.
 
k2orbust said:
Sounds like the Maguras solve the clearance problem, but could you possibly relace the spokes so the J-bends all come out on the inside of the flange? It's a pain but I had to do that to make clearance for my 12 speed cassette.

I too initially planned to build a Rohloff into my ebike, but when I did a detailed comparison its advantages couldn't justify the extra expense and weight. Plus of course it's not compatible with a rear hub motor, which is way preferable to a front hub for the hilly dirt roads I ride occasionally.

I've built a lot of wheelsets, but I've never done anything unusual like putting all the spokes coming out of one side of the hub. I know on the N171 hub they specifically instruct you in the owners manual to put all the spokes on one side of the flange. I could certainly re-lace the wheels, but as this fairly tight tolerance seems to be acceptable by brake manufacturers, I'll see how things shake out now that I've corrected the frame alignment issue. I think that was the major factor, and had the drive-side head tube been at the correct angle I might not have noticed anything. As it is, that side-loaded that wheel more than usual, and especially-so on roads with an extreme crown. I noticed at it's worst on a couple sections of road with a steep crown, as well as making right turns. The fact that trike wheels traditionally don't lean also compounds this because trike wheels carry a lot of lateral stress when turning. I guess that's one of the reasons why leaning-trikes appeal to a lot of people. Kind of makes me wonder if 26" wheels on the front are inherently less strong, laterally than smaller 24 or 20 inch wheels. One can only image what the weight and inertia of something like a tandem injects into the equation. I guess I'll find out. If somehow I still don't have enough clearance and I continue to get spoke contact with calipers in some situations I'll look into re-lacing with all spoke heads inside on the inboard side of the hubs. I'll have to read the pages of St. Sheldon and see what he said about that in regards to wheel building. I do know the alternating pattern of innies and outies helps distribute stress on the flange.

Like you, I really dig the Rohloff, and I'd dearly LOVE to have one on at least one build. I think they'd be great for something a velomobile, especially the ability to shift at a stop which is ALWAYS an advantage with heavier vehicles. I got into geared hubs a few years ago and I had Alfine 8 speed hubs on all my bikes. I had one on a Yuba Mundo, that was then put on a Surly Troll, and I also built a Surly Pugsley up especially because I wanted the Alfine in a fat bike, and finally, I laced one into the rear wheel on my bakfiets-style cargo bike that I built two years ago. That bike was originally supposed to have a front geared hub motor, but I was having wiring issues with it for some reason, and I just hated how much of a bodge hub motors look with all the damn wires everywhere. It's like there's no way to keep all that stuff looking tidy. The best cable management and housings and such and it still looks like a mess of wires and cables, just slightly neater. The Bafang mid-drive installed SO EASY and for the most part the wiring is much cleaner looking. Back to geared hubs though - the thing I found with the Alfine paired both with the geared hub motor and later the BBSHD, is that out of 8 available gears I probably never used more than about 3 or 4. Even with the assist level set very low it still seemed like several gears were just throw-aways because while you want that range with close steps unpowered, even with a little bit of assist you pretty much only need a few gears - at least for level ground cruising which is all Chicago is. Flat as a pancake. Spinning Magnets did a write up on geared hubs a few years ago and mentioned that in all the instances he knew of with Rohloff hubs paired with motors, the owners only used a few gears. Great to have the range unpowered, but otherwise mostly a waste of $1200+. One thing that has intrigued me is that Grin sells a rear hub motor with I think a 5 speed internal geared hub built in. It might be a Sturmey-Archer of some variety.

You're on the right track with your build though. It seems like ALL of the solar e-bike builds are based around direct drive hub motors. I sort of wonder if a DD motor installed in a mid-drive setup like with a Stokemonkey - can you still get regen and other DD benefits, or does that only apply when installed in a wheel? I think there's also a fine line between weight of vehicle and how appropriate DD motors are. I know Grin used two DD motors on their Sun Trip trike - in the front wheels. I'd like to know though if there was any detriment especially in climbing situations. Come to think of it, I think at least at one point in the video Justin did, they had to pull over and stop to let the motors cool off, so that's potentially a spot where a mid-drive might've been able to to keep going without overheating, provided it was kept geared so that it could spin at high RPM. Of course you then lose regen so I gotta wonder how important regen is in a solar situation in regards to how much energy it ca put back into the batteries.
 
kiltedcelt said:
I've never done anything unusual like putting all the spokes coming out of one side of the hub.

I was replacing some spokes today and realized my advice was hogwash with standard hubs and cross-3 lacing. Sorry about that! My hub motor has a huge flange diameter compared to a typical rear hub, and uses cross-2 lacing and there it was no problem.

It is true that small wheels are stronger than big ones, but who's to say where you start running into problems. More spokes! 48 spokes! 72!

In a solar touring scenario you will occasionally be low on power for the distance you have to go, so I fussed more about gear range than most e-bike builders do. Also there are more hills out where I live in California. But yes I ride my entire pancake-flat work commute in the highest or second-highest gear.

The new Kindernay XIV gearhub looks droolworthy too, but it will take time to challenge the Rohloff's reliability reputation.
 
Back
Top