Just another awesome commuter e-bike: rear hub BPM, LiPo
- Thread starter headwind
- Start date
Marc S.
100 W
Well, spokes work like a tension spring and have to be tensioned into the elastic deformation of the steel for a well build and long lasting wheel. Thats working fine with 2mm spokes in common aluminium bicycle rims. High end wheels use even thinner spokes (1.5 or 1.8mm) without sacrificing strenght or longlivety, but I've never used them.
Thick 3mm spokes need way more force to tension them into elastic deformation. Either you don't tension the spokes sufficient enough, resulting after short time in loose spokes and untrue wheel or you tension the thick spokes well, but may put more spoke force on the rim than a bicycle rim can handle, resulting in a deformed rim and again in loose spokes. Loose spokes will break after a while.
The other major flaw of cheap build wheels are burred spoke holes. By deburring spoke holes, nipples sit way better in the rim.
Thick 3mm spokes need way more force to tension them into elastic deformation. Either you don't tension the spokes sufficient enough, resulting after short time in loose spokes and untrue wheel or you tension the thick spokes well, but may put more spoke force on the rim than a bicycle rim can handle, resulting in a deformed rim and again in loose spokes. Loose spokes will break after a while.
The other major flaw of cheap build wheels are burred spoke holes. By deburring spoke holes, nipples sit way better in the rim.
Ahhh very interesting. I'll try this out next time the wheel goes wobbly.
When wiring up the new motor last night, I got foiled by the old "swap the yellow and green wires from the motor to the controller" trick
And it was after I had the wires all nicely cut to length 
When wiring up the new motor last night, I got foiled by the old "swap the yellow and green wires from the motor to the controller" trick
And it was after I had the wires all nicely cut to length Time for a quick "20 month review", I reckon. So... most importantly, the desire to ride is showing no signs of wear. 
Onto more mechanical matters, the axle in the hub motor snapped in half a couple of months ago. The Bafang wasn't really to blame, there are some unavoidable savage bumps on my regular, which I'm now (belatedly) treating with some respect. Thankfully, I had a spare motor ready to go, but it is Code 12 instead of Code 10. Since I've never needed to mash the throttle from standstill, the extra acceleration isn't really noticed. But it running out of puff at high speed is a bit annoying. Once it's up to cruising speed, there isn't much in reserve for overtaking/hills/etc. So someday I'll go back to a Code 10 motor.
The question I often think about is the suitability of RC LiPo for a commuter bike. Personally, I have some kind of geeky interest in tracking the batteries, but most people would probably get sick of the diligence required to run it safely. Eventually when a more forgiving chemistry can provide the same performance without too much extra size, I'll swap over. It would be nice to not have to mess around with Y-cables, balance leads, etc. The packs on e-bike kits are getting smaller and smaller, so this probably isn't far away. On the other hand, replacement LiPo packs are cheap and easy to get a hold of. I was reminded of this when a friend thought he'd killed a $400 battery due to a minor screw-up. After almost 2 years on the e-bike, I've killed approx 4 LiPo packs, all from user error (over-discharging or dropping them). Overall, I'm still happy to be running LiPo for the moment.
On my 13km ride, I use 6-8 Wh/km, depending on wind direction and laziness. The low energy usage is because I do a fair bit of pedalling, in order to get a bit of fitness benefit from the ride. This sees me use about half the battery's advertised capacity, which is good because I think the capacity is over-rated and I wouldn't want to be regularly using more than 70%.
So I'm pleased to report it's all still going well here.
Onto more mechanical matters, the axle in the hub motor snapped in half a couple of months ago. The Bafang wasn't really to blame, there are some unavoidable savage bumps on my regular, which I'm now (belatedly) treating with some respect. Thankfully, I had a spare motor ready to go, but it is Code 12 instead of Code 10. Since I've never needed to mash the throttle from standstill, the extra acceleration isn't really noticed. But it running out of puff at high speed is a bit annoying. Once it's up to cruising speed, there isn't much in reserve for overtaking/hills/etc. So someday I'll go back to a Code 10 motor.
The question I often think about is the suitability of RC LiPo for a commuter bike. Personally, I have some kind of geeky interest in tracking the batteries, but most people would probably get sick of the diligence required to run it safely. Eventually when a more forgiving chemistry can provide the same performance without too much extra size, I'll swap over. It would be nice to not have to mess around with Y-cables, balance leads, etc. The packs on e-bike kits are getting smaller and smaller, so this probably isn't far away. On the other hand, replacement LiPo packs are cheap and easy to get a hold of. I was reminded of this when a friend thought he'd killed a $400 battery due to a minor screw-up. After almost 2 years on the e-bike, I've killed approx 4 LiPo packs, all from user error (over-discharging or dropping them). Overall, I'm still happy to be running LiPo for the moment.
On my 13km ride, I use 6-8 Wh/km, depending on wind direction and laziness. The low energy usage is because I do a fair bit of pedalling, in order to get a bit of fitness benefit from the ride. This sees me use about half the battery's advertised capacity, which is good because I think the capacity is over-rated and I wouldn't want to be regularly using more than 70%.
So I'm pleased to report it's all still going well here.