abecrizer
100 mW
Hi everyone I am interested in what everyone here has to say about my project:
I currently commuting 7 miles down hill to work and the same route uphill to home.
With me pedaling only this takes me 20 minutes to work and 40-45 or so to get home.
I don't want to spend 40 minutes in the evening to get home after a shift, so I want some power assist.
I originally thought if I plugged away at it I would get faster, but alas this has not been the case.
I want to be exercising the whole time, but I want some motorized help onthe hills section.
My goal would be to get home in 20-30 minutes. I would want it to be a mid drive because it seems I can get away with a lighter motor
if the power is applied most efficiently. (In the summer the tempurature here is usually over 100 degrees)
My goals are:
1. Get home in 20-30 minutes, while exerting myself strenuously
2. Modify my bicycle as little as possible (keep my 3 chain rings)
3. Quiet
4. Add as little weight as possible
5. Cheap (If I was convinced a product was superior and would help me meet my other goals I could spend more money, but would prefer not to)
The first thing is: I want the motor to tie into the L crank. By adding a freewheel chain ring to the Left crank, either by welding on an aluminum
freewheel adapter after machined the crank for it to fit, or by getting a square Bottom bracket and putting a R hand freewheel crank over there
with modified pedal threads with some type of insert. When I pedal the motor will not turn, though if I back pedal it will have to be able to back drive)
I need help picking a motor, here are some thoughts so far:
1. Buy a E100 razor scooter, cut it up for the motor other pieces, add a jack shaft for a 2 stage reduction to the pedals
2. Right angle dewalt cordless drill with a sprocket instead of the chuck, tied into extra batteries (spins @ 500 RPM in low gear; also I know I need to remove
the anti-back drive device to back pedal, I found instructions how to do this on a robotic's club website)
3. 250 hub motor mounted similarly to what "Nader" has used.
My specific questions are:
1. Is 100w stupid? To me it seems I am probably 150-200ws by myself and adding 100w would be a HUGE help, but when you read articles
ppl make 250w seem punny. Is this b/c ppl are out for electric motor cycles or because 100 w will not help me much at all?
2. Is back pedalling necessary? It seems like it is so that you can put your foot down in a sudden stop quickly, but I can imagine learning to push back on the
motor and put the foot down
3. The dewalt uses a planetary gear box, and it seems that folks have said back driving a planetary gear box is not so good.
Also my dewalt drill is pretty loud.
4. Other motor recommendations that would fit my application?
Some things I considered and ruled out:
* AME 218 series right angle drive motor, I was dead set on this (I even made a cardboard model of the thing to figure out how
to mount it) until I realized it was worm driven and I would not be able to back pedal.
* R hand freewheel cranks, 4 chain rings, would have to move the motor chain while pedalling, and I don't thing the spacing would
work for the driving chain rings.
* factory mid drive kits: all seem heavy and over powered for what I am looking for (bafang is 250W and 3.8 kg and requires you to give up multi chain rings)
Thanks for any insight and help,
If it is at all relevant, my mechanical skills are moderately good IMO, though this project will stretch them for sure,
but I really don't know much about electronics and electromechanic stuff beyond simple circuits.
Which is one reason I picked the razor scooter and dewalt drill as they come with build in controllers I can just rewire into my application.
I currently commuting 7 miles down hill to work and the same route uphill to home.
With me pedaling only this takes me 20 minutes to work and 40-45 or so to get home.
I don't want to spend 40 minutes in the evening to get home after a shift, so I want some power assist.
I originally thought if I plugged away at it I would get faster, but alas this has not been the case.
I want to be exercising the whole time, but I want some motorized help onthe hills section.
My goal would be to get home in 20-30 minutes. I would want it to be a mid drive because it seems I can get away with a lighter motor
if the power is applied most efficiently. (In the summer the tempurature here is usually over 100 degrees)
My goals are:
1. Get home in 20-30 minutes, while exerting myself strenuously
2. Modify my bicycle as little as possible (keep my 3 chain rings)
3. Quiet
4. Add as little weight as possible
5. Cheap (If I was convinced a product was superior and would help me meet my other goals I could spend more money, but would prefer not to)
The first thing is: I want the motor to tie into the L crank. By adding a freewheel chain ring to the Left crank, either by welding on an aluminum
freewheel adapter after machined the crank for it to fit, or by getting a square Bottom bracket and putting a R hand freewheel crank over there
with modified pedal threads with some type of insert. When I pedal the motor will not turn, though if I back pedal it will have to be able to back drive)
I need help picking a motor, here are some thoughts so far:
1. Buy a E100 razor scooter, cut it up for the motor other pieces, add a jack shaft for a 2 stage reduction to the pedals
2. Right angle dewalt cordless drill with a sprocket instead of the chuck, tied into extra batteries (spins @ 500 RPM in low gear; also I know I need to remove
the anti-back drive device to back pedal, I found instructions how to do this on a robotic's club website)
3. 250 hub motor mounted similarly to what "Nader" has used.
My specific questions are:
1. Is 100w stupid? To me it seems I am probably 150-200ws by myself and adding 100w would be a HUGE help, but when you read articles
ppl make 250w seem punny. Is this b/c ppl are out for electric motor cycles or because 100 w will not help me much at all?
2. Is back pedalling necessary? It seems like it is so that you can put your foot down in a sudden stop quickly, but I can imagine learning to push back on the
motor and put the foot down
3. The dewalt uses a planetary gear box, and it seems that folks have said back driving a planetary gear box is not so good.
Also my dewalt drill is pretty loud.
4. Other motor recommendations that would fit my application?
Some things I considered and ruled out:
* AME 218 series right angle drive motor, I was dead set on this (I even made a cardboard model of the thing to figure out how
to mount it) until I realized it was worm driven and I would not be able to back pedal.
* R hand freewheel cranks, 4 chain rings, would have to move the motor chain while pedalling, and I don't thing the spacing would
work for the driving chain rings.
* factory mid drive kits: all seem heavy and over powered for what I am looking for (bafang is 250W and 3.8 kg and requires you to give up multi chain rings)
Thanks for any insight and help,
If it is at all relevant, my mechanical skills are moderately good IMO, though this project will stretch them for sure,
but I really don't know much about electronics and electromechanic stuff beyond simple circuits.
Which is one reason I picked the razor scooter and dewalt drill as they come with build in controllers I can just rewire into my application.