Mongoose Dolomite mid drive using front geared hub

[crashalot]

Juat started new build and thought I would document it here. Any suggestions / potential problems / concerns are welcome.

I ride the dolomite 10 miles every evening unless it is super hot (>100F). It is good exercise.

However there are couples of hills on the way back and on hot days it is very difficult to climb those hills when I am super tired.

So the goal is to have a boost from small mid drive at very low speed (5-10mph) to climb the hills.

I want to keep it super light since the bike is already 45lbs.

Motor is outrider 350 Watt front geared, 260rpm at 36V. The top speed can be about 20-25 mph. I am planning to reduce the speed to about 5mph for the lowest gear. Sprocket on crank is 36T and sprocket on motor is 32T.

I will use Chevy volt 9s1p pouch cells to get ~36V, 10Ah continuous. Planning to get 15 Miles range with pedaling.

 

[crashalot]

re cycled sprocket from old bike.

 

[crashalot]

enlarged the hole in the middle with step bit and drilled 6 mounting holes to match it with motor.

 

[crashalot]

the motor and the bike

 

[crashalot]

the bike

 

[DanGT86]

Sounds like a good simple reliable setup to make a mid drive. Why do you have such a large sprocket on the motor? Are you going to run through the cranks with the motor or go directly to the wheel? I'm curious what the rest of the plan is. Thats a lot of bike to pedal uphill on a hot day.

 

[crashalot]

Sounds like a good simple reliable setup to make a mid drive. Why do you have such a large sprocket on the motor? Are you going to run through the cranks with the motor or go directly to the wheel? I'm curious what the rest of the plan is. Thats a lot of bike to pedal uphill on a hot day.

Yes the motor will drive the crank (second sprocket on crank already installed). Regarding the sprocket size on motor, I am going with what I can salvage from my spare parts bike. The sprocket on crank is little bigger than what's on motor so it will give me some reduction and I have 7 speed on rear hub.

Bike feels little heavy than regular MTB but I like the handling of it. On days <80F, I can easily paddle couple of hills no problem in low gear.

 

[crashalot]

some more progress

Left sprocket will drive 7 speed on rear and right sprocket will be driven by motor. Right now I am using right sprocket to see if the chain stays and it is working good, have about 50 miles on it so far.

 

[crashalot]

Question for someone who is familiar with sensorless controller.

I bought following and connected motor , battery (+ve and ignition together) and throttle but the motor doesn't spin when throttle applied. I connected the self learn (white wire and the motor spins some times) without throttle.

On throttle plug, the red and signal (yellow) both show +5v even without connecting the throttle, so I am confused. Do I need to connect the brakes and anti theft etc..

 

[crashalot]

controller connections

 

[crashalot]

Figured out the connections now only thing left is mount motor to down tube.

The connections are labeled wrong. red, yellow, blk is PAS connector.

Throttle is 4pin blk,red,green, purple (brake).

 

[jpgey]

Hello crashalot, any news on your built ?