Motobecane DS Fantom, BMC 600W torque and now Lipo build

[shock]

Sounds right in spec for lipo power. I did 23 miles yesterday, of city. Ended @ 44. Waited until now to fire up the charger. Looking forward to some trail rides.

 

[kfong]

Hey Joe, the trails are in great condition. Wearing gloves to keep my right hand functional so I can ride. I road from my house to the post office at 16 mile then down 16 mile to John R. From there straight north to Bloomer park. Covered all the trails their at least twice then on to paint creek trail to Stoney Creek park, rode the fast trail section by the BMX area. Tried the BMX section but the bike needs to be more like my RC build to work it. Realize I was cutting it close so headed back the same way. Going to have to drive to my favorite single track at highland state one day. It's been a while since I've had a fall, that place usually gets me on the ground. I wish we had more advance trails like out west. I did have to bail recently at dodge park going up a plank, need more practice in that area. Bike came down hard on its side but was fine. There is also a nice drop off, great for getting some air. I've had a few close calls on it. Hopefully they keep adding new stuff.

Another 30 miles today 6/9/2012, all trails. Went to Pontiac state park. The loop is a little over 10 miles. Was in good form the first time around, second time through I had a hard fall. Was thinking I could use full body armor after getting up and checking my right elbow. Ground was hard, with mostly buried rocks. Was getting sloppy with fatigue, had one more hard fall on the third loop around. Started slowing down after that and just took it somewhat easy. Bike is holding up with all the trail abuse. It's no DH frame, but neither is it heavy like one. I did bottom it hard during one drop off, which had me concerned about the rear shock. I've been very happy so far with the performance of this bike. Very nimble in the trails, which is all single track.

 

[kfong]

It's been a while since I posted an update. Was pretty much riding it till I started working full time again. Not much riding these days due to weather as well. About 3 weeks ago I actually had a break down. The ratcheting sound after pushing the bike pretty hard up a hill became quite loud and soon after just a hum without any power to the wheels. I suspected the clutch had finally given up. About a week later, I finally had time to take it apart. I found that keyway had sheared completely in half. It had damaged the surface as well, but this wasn’t much of a problem to smooth out. It must of taken a lot of torque to do that. I replaced the keyway with one I milled out. The clutch was also replaced since it had much more rolling resistance than the new clutch and I was not about to do another rebuild. The good news is the gears look great after 3 years of hard riding and jumping. Here is a picture of it after all the grease had been cleaned off. It looks like it was just bought. The clutch replaced was another V3. It sounds like the newer V4 clutch has even lower rolling resistance. I will have to go that route next time.



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This weekend was the first time I was able to take it out riding again. Sure felt good to hit the trails. It’s been warm for this time of year as well. The bike performed great as usual and left me with smiles. Looking forward to spring. I should have replaced the rear tire while I had it apart. I need to find a good tire that can last a bit longer than the soft trail compound of the velociraptors. The center is pretty much bald with the sides still looking good, and this is pretty much after one season. Any ebike trail tire recommendations out there? You can see the wear is actually into the liner now.



I still need to get the covers completed so it fully encloses the Lipos. It should be done this winter. I had a bad crash worth mentioning while riding the trails at night about a month ago, clipped a tree and went down hard. Stopped night riding after that. Need to have a lot more lighting if I were to do it again. Only had one magic shine and a low power helmet light.

 

[oatnet]

Glad you are OK after your fall. Do you think that might have anything to do with the sheared key? I have not seen a report of that on BMC/MAC before. Thanks for the GREAT data point on gear wear in the BMCs - guess we don't need noisy steel gears after all! :lol:

-JD

 

[kfong]

Crash was all my fault, just didn't see the tree with the low light. With work, I had limited trail riding time. Thought riding at night with lights would work out, but really needed more lighting to be safe. Until I get that worked out, no more night rides. Weather now is too cold, time to work on bike builds.

Yeah, I expected to see more wear after cleaning off the grease. The keyway was relatively easy to replace. Still very happy with this motor as my choice for trail riding. Not much I would change on this setup.

 

[oatnet]

Crash was all my fault, just didn't see the tree with the low light.

Sorry, I meant do you think your fall is what might have damaged the key, and started the shearing...

-JD

 

[kfong]

The shearing probably happened over time. I've had so many falls on the bike, that pinpointing it on one fall would not be likely. Hard acceleration and hill climbs probably did it in. The keyway is soft as well, the one I replaced it with I decided to harden with a butane torch. Not sure how well this works, waited till it glowed to straw color, then dropped in water. I figured since the gears looked good, I might as well let them take on the stress.

 

[teklektik]

I replaced the keyway with one I milled out.

BMC motors use a 5mm x 5mm x 11mm key. You can buy a 25mm (1") piece of 5x5mm keystock from many power equipment service/repair stores for a buck or two - it's a fairly common item. File a rounded end, trim to length, then file other rounded end. Also, FWIW - the key is the bit of metal that fits into the slot or keyway.

 

[kfong]

Thanks teklektik, good to know. In my case it was just easier to have the CNC just cut a few out. Had to guess on the dimensions. Will use your measurement next time.

 

[shock]

Hi Vince, glad to see the motobecane is still up an running Still admire your battery and wiring setup, very nice.

I am in the course of completely rebuilding my motobecane right now, upgraded phase wires and air cooled the hub, going to a 12FET lyen, and 18s. I found some 6cell 5k mah blue lipos dirt cheap again on black friday hobbypartz sale. I got 6 of them. I am planning on regen so I want to beef up the torque arms, and yours look the part. Aquired some DocBass steel torque arms but really my last resort as I don't want to glue them to this particular frame. Maybe we could meet up and I could pick your brain a bit about a good solution. I would have no problem paying you for your time and materials if you have the time and resources to CNC me some good bolt on torque arms. Wondering if you still have the CNC file for your torque arms, as I believe the swing arm is the exact same as your bike.

-Joe

 

[kfong]

Hi Joe,

Working full time again, and have so little time these days for ebikes. Once riding season is upon us, I will have zero time. The parts were made of stainless steel, it was a bitch to cut on the micro mill. I will not do it again unless it's for my own stuff, since loosing some cutting bits is guaranteed. It also takes forever to cut since the passes have to be very light. You are better off getting it cut on a waterjet from one of the local shops and getting it customized to your hub motor axel since mine was for the BMC V2T.

 

[kfong]

An update on the Motobecane. I've been very happy with this setup; there isn't much I could do to improve on it for trail riding. I have just been riding the crap out of it. I had considered putting in a Thun torque sensor to allow more pedal input, but after doing some research and the fact that Thun only comes in a tapered spindle has turned me off on the idea. I'm hard on the bottom bracket and have pretty much trashed my pedals on the trails hitting rocks, ect. The ISIS spindle on it has started to creak, and at least the bearings will need to be replaced eventually. The batteries are holding up but have lost some capacity; I'm getting about 10ahrs of actual use. I get about 15 miles of trail riding while pedaling. I’m hoping the packs will last a few more seasons, but the gradual capacity loss isn’t so great. Since I can’t improve much on the ebike portion, it felt time to put money into the ride performance. I’ve been wanting to change out the front Rock shock Tora forks and replace them with a high end Fox. I also picked up an adjustable seat post as well from Fox.

I went with Fox since I've been very happy with the RP23's for my rear suspension. The original Rock shox gave out last year and could not be fixed with a rebuilt kit. Not a brand I would buy again. The bike frame is holding up well; Fairly light, nimble, and the geometry works well in the trails.

 

[kfong]

This bike is still my favorite trail ride and with the new front Fox fork its performance has jumped up a few notches. I knew it would be better than the Rock Shock Tora, which was only a spring dampened fork. The Fox 32 float is a full on air shock with plenty of adjustments to fine tune the ride handling. You actually get that buttery smooth feel a lot of pro riders talk about. It’s an expensive fork, but does what a suspension fork is supposed to do and is well matched by the RP23 rears. The new seat post is cool, it has 3 settings. This is really more of a luxury item for me. I don’t find myself challenged enough here in Mi. to use it, but will come in handy when I do stupid stuff that I have no business trying.

The bike is holding up well. The only problems I have now is the loss in battery capacity. I plan to remedy that this winter with an updated pack. I’m also still fighting rear wheel flats. I was doing well with thorn tubes but they would eventually fail at the valve seat. It would tear due to the thinner presta column. My next plan is to drill out the rim to accept Shrader valves, hoping that the thicker column has a better chance of not tearing due to the hub motor forces.

The converted front tube to a Stans tubeless setup has been great and I’m sold on it. No flats and I did see a trickle of the white liquid mid summer, so I know it did its job. I am tempted to do the same with the rear, but I’m really concerned of the side loads I put on it during power slides. If the sidewalls give, it would be an instant flat that can't be fixed in the field. I should order some of those snake tubes just for a backup. I guess I will just commit to it and see what happens.

Here is a pic of what the bike looks like currently.

 

[kfong]

Still fighting with my never ending battle with rear flats. I did attempt to go tubeless, but was not successful due to the type of rim and perhaps the tire. My front tire has a rim that is more V shaped. As much as I tried, the leaks from the sides just would not seal. I placed an order for an actual Mavic tubeless rim to try out next season, but will need to spoke it to the spare hub.

In my haste I picked up a super thick slime tube so I could ride this weekend. Something I vowed not to ever buy, but could not find any thorn tubes locally. My first ride out, I get a pinch flat. Could not believe my luck Impossible to fix due to the slime and useless. Long walk back from the trails and pissed. Knew better, and was kicking myself for not waiting. At least with a non slime tire it can be patched in the trails. Hoped I could get away with it since the tube was thick. Pressure was set to 40 psi. too!

 

[kfong]

Update on my war on flat tires. Today I had a flat on my front tubeless setup after 2 seasons of riding. This is using the Stan's no leak and a converted rim. It left me stranded in the woods, had to huff it back to the car. Pumping the tire by hand wasn't going to provide the air flow needed to create the seal. After getting home and taking it apart, I found a big blob of the stuff looking like it came from the alien movie set. The Stan's stuff had dried out and clumped together. I had crashed, causing the front tire to go sideways. This broke the seal and instantly let out the air pressure. I'm no longer sold on the Stan's tubeless tire solution. Eventually the stuff dries up into a big clump leaving you stranded. With a tube, I would of been able to service it in the woods. I found some other stuff that won't dry out, but it reminds me of the dreaded slime crap. I think it's back to thorn tubes up front with a tire liner for good measure. Going to miss the light feel of the tubeless tire though

Currently, I'm running Avenir thorn tubes with the shrader valves in the back. I had to drill out the rim to accept the larger size valve. Presta valves kept tearing at the valve stem. There isn't any support due to the narrow stem compared to the shrader design. I'm also using a tire liner. It currently is holding up, stem is on an angle due to the rotational torque, it would of tore off if it was a presta valve. This is the only setup that works, you still get occasional flats, but usually fixable in the woods.

Packs are hovering at about 9.5 ahrs of useful trail riding. The rest of the bike has been great.

 

[full-throttle]

Tubeless can 'burp' under extreme cornering, or while running too low pressure, or bad match of rim and tire, or combination of the above.
I'd suspect tyre/rim combo to start with. What are you using? Hope not some 'ghetto' stuff..

The solution does dry out. Depending on the humidity and tyre construction. You shouldn't ignore it and add more sealant by unscrewing the valve core. Personally I go through the tyre before sealant needs replacing.

And lastly - ALWAYS carry a tube!

 

[biohazardman]

I have trouble with flats as well. The last three and the only I think I have had in a couple of years were caused by the tire sliding on the rim cuz of braking forces with over sized rotors and tearing the tube stem at it's base. If I keep after the tire slippage, by letting the air out and pulling things back into place making the valve stand straight up again regularly, I am golden else, I have flats even with 60LBs of pressure in the tire. Been thinking of a little contact cement on the rim tire interface. Probly won't take much. With your pressure set for trail riding things have to be far worse I wish you luck.

 

[kfong]

FT, yeah it's a ghetto, but done properly. Lasted 2 years of hard riding, and it wasn't the ghetto part that gave out. I'm just turned off of what I found. The latex alien looking clump and dried out sealant wasn't what I expected. Adding more sealant doesn't liquefy what's in the tire. If you don't clean it out each year you end up adding weight and imbalance. Carrying a spare tube only works for the front tire. My rear hub motor would not be possible to service.

I am giving this tubeless setup one more try with a sealant that supposedly won't dry out, I do like how light and responsive the tubeless tire feels. I have a tubeless Mavic rim on order and will look for a tubeless tire. I will put this setup on my spare BMC motor. Determined to get rid of flats, since that is pretty much all that breaks down for me. Expensive fail if it doesn't work out.

 

[kfong]

Bio, same problems with my rear tire as well.Will have to do as you suggested, and reposition the tire. It's being stressed at the stem. That's why I won't recommend presta valves for this application.

I have trouble with flats as well. The last three and the only I think I have had in a couple of years were caused by the tire sliding on the rim cuz of braking forces with over sized rotors and tearing the tube stem at it's base. If I keep after the tire slippage, by letting the air out and pulling things back into place making the valve stand straight up again regularly, I am golden else, I have flats even with 60LBs of pressure in the tire. Been thinking of a little contact cement on the rim tire interface. Probly won't take much. With your pressure set for trail riding things have to be far worse I wish you luck.

 

[made_in_the_alps_legacy]

Kfong, brilliant built!
I used to fix the tyre to the rim with some silicone, the one sold for joints to be applied with caulking gun
It's reversible... good luck

 

[kfong]

Time to get the bike ready for the riding season. Last year my packs were wearing out and I was getting 9ahs of usable run time. I got a deal on some used packs from shock. They are the same brand but at 5ahr a pack, making it easier to setup. I've been wanting to try my idea of encasing the packs in carbon fiber to make them fireproof. As much as I like using Li-Po. The fire hazard is always something I'm concerned of. This year I've taken it to the next level and now I think I have a solution. I'm quite happy with how the packs turned out. Not only are they fireproof, but they are also compressed by a full vacuum. I'm hoping this keeps the pack life longer, but only time will tell.

 

[z50king]

Nice read and thank you for the pictures.

I bought 4 of the Blue 6S 5Ah packs two Black Fridays ago on super sale. I am still running them in my goped 6S4P and they are giving me about 11Ah overall from the 19Ah they gave me when I started using them.

 

[kfong]

These were inexpensive packs, I'm hoping the added compression will help with the packs lifespan as well as any fires. My first packs from them lasted 3 seasons. Lipos also age with time so I felt they worked out well for the money.

Nice read and thank you for the pictures.

I bought 4 of the Blue 6S 5Ah packs two Black Fridays ago on super sale. I am still running them in my goped 6S4P and they are giving me about 11Ah overall from the 19Ah they gave me when I started using them.

 

[z50king]

These were inexpensive packs, I'm hoping the added compression will help with the packs lifespan as well as any fires. My first packs from them lasted 3 seasons. Lipos also age with time so I felt they worked out well for the money.

I got them for 40 dollars a piece. I am still running them. The Goped draws very high amperage and it's worse because it's only at 24 volts. They have not puffed at all. Still hard a rock throughout each pack

 

[biohazardman]

Nice job on the battery packs light, strong and some fire resistance as well. Looks like it may werq out good. Nice forks too. I'm still running my a123 26650 pack and after 4 years and 10K they seem to get me about the same distance. Have more for the next 2 builds, in progress, as well.