SlowCo
1 MW
This is a great DIY mid drive idea!
I might use it on my bike next year. Thanks for sharing and keep enjoying your bike!
I might use it on my bike next year. Thanks for sharing and keep enjoying your bike!
That's an interesting motor. Looks like it can handle lots of current and power. If I had an 8S pack, I would be very tempted to order one.falcongsr said:Would using a 60kV motor such as this one: https://alienpowersystem.com/shop/brushless-motors/aps-5065-outrunner-brushless-motor-60kv-1800w/ potentially open up higher voltages or simpler reductions?
falcongsr said:Would using a 60kV motor such as this one: https://alienpowersystem.com/shop/brushless-motors/aps-5065-outrunner-brushless-motor-60kv-1800w/ potentially open up higher voltages or simpler reductions?
Tommm said:Then again for your application a bosch 250w mid drive would suffice, with much higher reliability.
falcongsr said:If you were starting from scratch would you choose a lower kV motor if you had access to them?
Thanks!
falcongsr said:Can you share how you mounted the 90T wheel sprocket to the chainring? Your sprocket doesn't look like these: http://electricscooterparts.com/sprockets25chain-wheel.html
Thanks!
I hear you. The trick would be to find about 10 other guys who want the same thing. Negotiate a group buy of sprockets. Find a machine shop with a CNC mill and negotiate a good price. I suspect the machine work could be done for under $30 each. If anybody wants to take that on, I would be happy to provide the autocad drawing file...falcongsr said:Thanks for the details and gearing info FZBob. I was afraid you'd say you customized that 90T sprocket. A little outside my skillset - I'd need to buy a few spares for sure!
wineboyrider said:Nice to finally find a decent sensored turnigy motor 8)
Tommm said:These RC motors are not made for bike applications at all.
edblanch said:Bob,
Great build, that I would like to replicate here in Australia.
I had a couple of questions :
1 Where did you get the motor mounting bracket from ?
2 What Voltage battery pack are you using as I've got a 48V 10AH unit I would like to use.
FZBob said:falcongsr said:If you were starting from scratch would you choose a lower kV motor if you had access to them?
Thanks!
If I was starting from scratch, and there was a good selection of 60 KV motors, I might go 8S. Same for 80KV and 6S. Just size the battery pack for the same number of Watt Hours.
Kepler said:Got to ask, why 8S with the 60kv motor? My calcs come up with 6S and 60 kV at 10:1 being a nice combo. Calculated as opposed to real world can be be quite different I know.
neptronix said:Okay, three things..
1) there's a company in the USA called rebel gears that can cut up pretty much any sprocket you want. I had purchased a custom one from them and it was very high quality..
http://www.rebelgears.com/
2) alien power sells sensored RC motors that go all the way down to 30kv. These are usually in the multi KW range. I don't know how high of quality they are, but if you wanna run 10S-12S for this kinda build, you might find something that's perfect from them.
3) for making a standardized kit that fits muliple bikes, i think a handlebar stem mount to the seat tube could work great. Check this thread for more info:
https://endless-sphere.com/forums/viewtopic.php?t=79254
FZBob said:My calculations showed the same thing. However, my calcs showed 3S with 125 KV, and it ran like a diesel - all the torque at low cadence. When I tried 4S, the same motor woke up. Nice flat torque curve.
neptronix said:kV under load is always 10%-20% lower than unloaded kV in an old fashioned PWM controller.
This figure can vary more in a FOC controller.. based on the settings you use.
Thanks Neptronix! I just ordered a custom Aluminum 90 tooth #25 sprocket from Rebel Gears. About $46! They were very nice to deal with. I requested a 3.47" dia center hole and 4 ea 0.390 dia mounting holes on a 4.094" circle. This should match the standard 104 bcd bicycle chainring pattern and bolt right on my standard crankset. Plain disc, with no lightening holes. It will need to be spaced outward with some washers for clearance. The new aluminum sprocket should weigh 200 grams as built, and I will probably lighten it to 64 grams.neptronix said:as for the rebel gears sprocket.. i bought it 5 years ago and forget the price. In the $50 range for a custom 39T 415 sprocket with a bicycle disc brake mounting pattern.