Voicecoil's red, fully rigid commuter

[voicecoils]

This build is essentially complete now. I'm updating this first post for the benefit of those coming to the thread and starting at the top.

Before:

drive_side_low-s.jpg (142.17 KiB) Viewed 1994 times

After:

file.jpeg (137.98 KiB) Viewed 1988 times

The Plan: Take one of my current bikes and transform it into a nimble mountain climbing goat!

The bike: Full cromo frame including the front fork. Disc tab on the back, recently powder coated. Sun Ringle rims front & rear. The rear is laced to an 8speed Shimano Alfine internal gear hub, operated by a twist shifter.

Parts list
Motor: Banfang PMGR (from ecrazyman@gmail.com)
Controller: Analog Crystalyte 24-72v 35A
Throttle: Crystalyte half twist grip
Charger: 900W 72v10A from http://www.BMSBattery.com
Front Rack: CETMA 5 rail. Somewhere to put the groceries...http://www.cetmacargo.com (not on my bike at this moment)
Batteries: 24s1p pack of 3.3v, 10ah cylindrical cells (Headway packs from http://www.e-mtb.com.au)
Spokes: Cheapies from ebay 216mm for a 1-cross on a 26" rim. I'd suggest 214mm though.
Rear Hub: Shimano Alfine 8-speed, silver with splined disk brake rotor
Gear Ratio: 48 tooth front sprocket 16 tooth rear sprocket ~78 gear inches when hub is in direct gear (4th, 1:1)
Rim: Rynolite 26"
Monitoring: direct plug-in Cycle Analyst on the bike, stand alone used for monitoring charging
Battery box: Care of the EngineWisperer (http://www.enginewhisperer.com)

Performance:

Preface:The Bafang must be pedal-assisted to avoid overheating or thermal meltdown. It screams and acceleration is mild if you twist the throttle from a dead stop or hill with no pedalling. The Bafang cannot handle high current without rising in temperature rapidly. At 72v nominal, 12-14A seems safe and 18A seems like flirting with the devil (but is lots of fun!). Even limited to 9A, the assistance is quite useful. Pedalling the same bike with no assistance is a great reminder of how much work the motor does. I'm running 2 plastic gears and 1 metal gear. I've killed some gears and melted some hall sensors out of their slots in the motor but I haven't killed the motor.

Details
At 72v14A I can climb at 35 km/h, cruise at 45 km/h and descend at 55 km/h. (all with pedaling)
The no load speed is around 60 km/h.

Efficiency:
To be updated soon.

[Mark_A_W]

At 72v you'll need a disc brake on the front

Make sure you get the right RPM motor for the speed you want and volts you have.

At 72v, 28 amps I would have gone a rear motor..

Also, I'd be VERY careful about frying the motor, that's 2000 watts through a motor rated at 250-350 watts. BigH fried a 408 at 72v 20 amps I think, maybe 35 amps, and it's A LOT bigger motor.

If you go faster than 45kmh I think suspension is a good idea, at least front suspension.


Your rim has 32 spokes, ebike motors typically have 36 spokes, at least in my experience.

And the front end will be heavy as it is, I'd be VERY scared of that front rack, you'll lose the front end...I've done that twice now, although never under power, just lost traction cornering.

[voicecoils]

At 72v, 28 amps I would have gone a rear motor...
Also, I'd be VERY careful about frying the motor, that's 2000 watts through a motor rated at 250-350 watts. BigH fried a 408 at 72v 20 amps I think, maybe 35 amps, and it's A LOT bigger motor.

Rear wasn't an option with this bike due to the internal gear hub.

That's the controller info but I don't have numbers for controller efficiency or power rated continuously and over shorter intervals (seconds, mins). I may use the Cycle Analyst to try to limit current so that ~1.5kW is the max going in to start off with and see how the motor and controller are behaving thermally.

If you go faster than 45kmh I think suspension is a good idea, at least front suspension.

I can move parts over to the devinci later which has mid level Marzocchi forks it it turns out to be a crazy speed demon.

Your rim has 32 spokes, ebike motors typically have 36 spokes, at least in my experience.

You counted my spokes? yes, 32 I'll try to find knuckles front wheel and count his, thanks for the heads up. The .pdf drawing doesn't show them. [EDIT] yep, 3 spokes: http://endless-sphere.com/forums/download/file.php?id=10753&mode=view

And the front end will be heavy as it is, I'd be VERY scared of that front rack, you'll lose the front end...I've done that twice now, although never under power, just lost traction cornering.

The rear will wheel will likely be just a bit lighter then the front in the end, it's a heavy hub too. So wheel weights will be reasonably balanced. If you look around at couriers the weight's almost always on the front (and/or on their back!). That rack is apparently good for 18kg before handling gets a bit wacky. http://cetmaracks.com/faqs.htm#Dude,_why_the_front


Thanks for the replies Mark

[docnjoj]

The 32 hole to 36 hole spoke arrangement is very easy to do! Check Sheldon Brown/Harris Cyclery!
otherDoc

[voicecoils]

The 32 hole to 36 hole spoke arrangement is very easy to do! Check Sheldon Brown/Harris Cyclery!
otherDoc

I can't find the link though I've used the late Sheldon Brown's resources many times.

Any idea of the effect on rim strength?

[Toshi]

I like the way you think. Here's my similarly red, rigid, and internally geared take:



That looks to be a Planet X fork, no? Rigid as all get-out. I ran one on an Evil Imperial and hated the beast -- too stiff!

Unless you plan on only pedaling on slow climbs and at stoplights I predict you're going to have to up the gearing in the chainring and sprocket. In the photo above I was running 38-21t with a Nexus 7 hub, and now I'm a bit tall if anything now: 48-16t with that same Nexus 7. 100 rpm in top gear is 35 mph! If I had my druthers I'd do it again with maybe a 44-16t setup.

[voicecoils]

you got it, planet x. not a disc compatible one unfortunately though. I don't quite understand what has happened to planet x these days, it's all tri/time trial/cyclo/etc... changed owners, sold names, who knows.

The evil imperial was one of my fantasy bikes a few years ago, when they made a gboxx prototype I was drooling.

Your bike looks great, what's the URL for your build in this section? [edit] it's in your sig, doh!, how about a link to your performance stats on the bike? It looks practical for commuting & carrying stuff I plan to stay a cyclist first, ebiker second. I suspect your in a similar situation. I don't understand $100 bikes with $3k of ebike kit on them. Nice to see a few decent bikes around.

Hopefully the Bafang PMGR will be a strong hill climber and torque-y off the line. If so, I will certainly change my gearing, with a larger chainring. Here's the hub ratios:

8 1.615:1
7 1.419:1
6 1.223:1
5 1:1
4 0.851:1
3 0.748:1
2 0.644:1
1 0.527:1

[Mark_A_W]

I plan to stay a cyclist first, ebiker second.

Umm, you plan on going straight to a 2000w setup....ten times the legal limit.

What was that you were saying about cyclist first?


But I do agree about the $100 POS walmart bikes. Unfortunately it's harder to marry the e bike gear to a more expensive bike (9 speeds, no V-brake pins on the rear wheel, stuff like that), but I'd never trust a toy bike to stand up the abuse my bike gets!

[voicecoils]

I plan to stay a cyclist first, ebiker second.

Umm, you plan on going straight to a 2000w setup....ten times the legal limit.

What was that you were saying about cyclist first?

But I do agree about the $100 POS walmart bikes. Unfortunately it's harder to marry the e bike gear to a more expensive bike (9 speeds, no V-brake pins on the rear wheel, stuff like that), but I'd never trust a toy bike to stand up the abuse my bike gets!

Easy staying a cyclist first with 3 other bikes in my stable With the red bike (once it's actually running!) I plan to gear it so that I can apply a meaning full contribution by pedaling (whether that's increasing top end speed or at some other point).

For legality sake let's stick to: The bike will be limited to 200w, with human pedaling as the the primary motive power input.

Also, if I was drawing 2kW from the batteries, I think power at the wheel (on a dyno for example) would be substantially less. In contrast, with my legs I'm reasonably confident I could achieve 0.2kW on a dyno as I'd only be loosing 2% to the chain + spoke twisting + frame flexing.

[voicecoils]

Started reading your thread, AWESOME torque arms Toshi, that's an inspiration for me

[Toshi]

Your bike looks great, what's the URL for your build in this section? [edit] it's in your sig, doh!, how about a link to your performance stats on the bike? It looks practical for commuting & carrying stuff I plan to stay a cyclist first, ebiker second. I suspect your in a similar situation. I don't understand $100 bikes with $3k of ebike kit on them. Nice to see a few decent bikes around.

Thanks. That was exactly my philosophy, too. Yeah, those torque arms are pretty sweet, eh? For those seeing that photo for the first time I must put the disclaimer that I had someone else build them -- my skills do not include welding!

Having electric assist seemed a nice way to rationalize some (heavy) commuter-friendly parts that I'd never put on my minimalist road bike, namely a steel rack, boat-anchor Nexus hub, much-wider-than-23c tires, full metal fenders, and more than a weensy little LED for lighting. (Now I'm up to 5 weensy LEDs! take that! )

Performance stats, like everything else, is buried in that thread. 35A limit at the CA, 48V nominally, ~53V on the bike, 24 mph on the flat, climbing 6-7% grades at 18 mph with moderate contribution by the ol' legs, and tall enough gearing to allow me to contribute my token 200W even past the no-load speed of my 407 motor (~32 mph).

[voicecoils]

Your performance sounds pretty decent, how does the rigid ride feel at that speed?

What did the torque arms + fork mods cost? Here in Australia paying someone to weld or machine anything gets costly fast. I suspect a similar job here would cost me $250 (mostly due to paying a skilled person a living wage, an the fact that small shop machinists are a dying breed).

[voicecoils]

WEIGHT

My finished bike weight goal: 27-28kg (not including charger)

Stock bike:............14.24kg (grams count! )
Bafang PMGR:.............3kg (claimed, will weigh when I get it)
Batteries:.............~8.61kg (LifeBATT), OR
...............................~7.2kg (Headway) both claimed weights
Controller:..................??kg ecrazyman 72v, 28a controller

Other bits:..................??kg disc brake upgrade, wring, copper busbar, cycle analyst, battery packaging/enclosure

[voicecoils]

possible wheel (which I already have) it's quite straight, just need some spokes the correct length:

[Mark_A_W]

If you are using a steel fork, just cut yourself some torque arms from some 3-4mm stainless sheet with a jigsaw and files. Knoxie did this.

Hose clamp it to the fork.


If you do end up with ally suspension forks you'll need to do what I did with the extra reinforcements.


And stop worrying about the weight. You'll find it's completely irrelevant...until you have your first electrical failure and you have to pedal it up a hill (so don't ditch the low gears!).

Mark

[voicecoils]

If you are using a steel fork, just cut yourself some torque arms from some 3-4mm stainless sheet with a jigsaw and files. Knoxie did this.

sounds like a plan, and quote do-able. You must admit Toshi's torque arms look sweet though! If I had a disc mount welded on I might have a torque arm mount done at the same time, we'll see.

And stop worrying about the weight. You'll find it's completely irrelevant...until you have your first electrical failure and you have to pedal it up a hill (so don't ditch the low gears!).

So, you don't want me to to count each gram of grease in my hubs and bottom bracket and consider how much weight I can save by upgrading to Ti bottle cage bolts with chamfered heads?

I do actually have a Park Tools bike scale, but sadly it's accuracy is only +/- 10 grams

[voicecoils]

What do you think of using that rim? Cutting out the hub and respoking it? Bike shops always recommend using new rims for each wheel build due to the stresses placed on the rim.

I've updated my order to Keywin, I added a 400w 48v DC powersupply with +/-10% voltage trim to bulk charge each 12s1p string fast then top off with the voltphreaks. Secondly I added a thumb throttle. I'll see which I like better for control, thumb or twist.

[Toshi]

The rigid ride with 1.75" tires at 75 psi is less rigid than the road bike with carbon fork and 23c tubulars at 120 psi. The lack of hand positions with flat bars does get tiresome, however.

The torque arms, fork, and fork mods cost me $88 USD altogether, although that was kind of a buddy deal.

[Mark_A_W]

Abraham, bike shops just want you to buy more rims..

I rebuilt my motor into a Pivot downhill rim recently that I got off ebay for $20. The rim is fine, in fact with the new rim the bike feels completely different - amazing change actually.

If the rim is good, use it. Getting suitable 12G spokes is the hard bit.

[voicecoils]

Mark,

money, liablilty, probably a few more reasons they want you to buy new rims but there is also probably some truth in it. Still, the wheel is in great condition, I don't plan on running the bike as a singlespeed again so probably won't be using that wheel any time soon. I'm up to 6.5 wheelsets total so I'd like to avoid buying more if I can !!!

Wheelbuilding is something I'd like to learn, not 100% sure this is the project to learn on though. At least it's a dishless wheel (the correct term I think) and I have http://www.sheldonbrown.com/wheelbuild.html to aid me

12ga spokes the correct length is proving to be tricky, google has not been helpful on that one. I may just order 13ga ones from ebike.ca (along with the cycle analyst) since they do custom lenghts for reasonable prices.

[Mark_A_W]

I got my spokes from Brett Solarbbq.

But the hard part is getting the length right. I was sure I wanted 180mm spokes, but when I built it I realised I needed 185mm spokes, as the nipples didn't poke through as far as I thought they would...

[Mark_A_W]

How to build a hub motor wheel up:
http://www.users.bigpond.com/solarbbq/spoking.htm

But for god's sake don't use pliers!!

[EVTodd]

Hey Voicecoil. Is that an EV Warrior fork?

[voicecoils]

Hey Voicecoil. Is that an EV Warrior fork?

no, early Planet X fork. Cromo steerer, cromo legs. VERY STIFF

[voicecoils]

Parts that have arrived: (pics soon)

* Bafang PMGR hub motor (smaller then I expected!)
* ecrazyman 72v 28A controller (need to obtain 20mhz resonator and perform mod)
* thumb and twist grip style throttles

* 48v 8A DC power supply for bulk charging of LiFePO4 36v strings
* 12 LiFePO4 single cell chargers from Voltphreaks

Parts ordered and yet to arrive:

* CETMArack front rack

Things to order or organise:

- 20-mhz 3 wire resonators (qty 1)
- CycleAnalyst
- wires, connectors
- mounting hardware
- torque arm?
- batteries
- Spokes
- lacing motor to wheel