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No drive uphill - grinding noise Radrunner 2

Started by Naz, July 27, 2023, 03:11:37 PM

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When on flat ground, the bike rides ok with power, but if i go uphill, there is a grinding noise from the rear wheel & it no longer is propelled.

I pulled the motor & all the gears look fine within the rear hub, nothing eaten up.

Any suggestions?


Is it the same with PAS or throttle? 
What happens if you open the throttle on flat ground?
Does it happen on hills that aren't at all steep?
Does it happen as soon as you come to a hill?
Does the pedaling continue to work normally?


it only makes the grinding noise when going up hill it never had issues with prior.

works fine on level ground with throttle.

if you put the front wheel against a wall & throttle it, it makes the noise.

no issues pedaling, pedals normally & no noise when pedaling either.


Hmm... the motor turns when the wheel is stationary...

A couple of years ago, I opened up the hub on my Radrunner enough to check the planetary gears, but I didn't take the carrier apart. I think it has a freewheel so that the rolling of the wheel won't force the motor to turn. The freewheel may use nylon pawls. if they're bad, I don't know where to get replacements...




I believe the carrier is riveted together. Some dealers sell the assembly pretty cheaply.

I checked Amazon for "ebike planetary gears." They show several with their measurements.


The planetary gears are fine, after taking it apart.

I believe the issue maybe with what ever locks the axle in 1 direction.

by hand, i cant get the axle to slip or make noise. the axle spins freely in 1 direction & locks in the opposite.



Note that they call them clutches. The clutch is built in. I don't remember if mine would slide off the shaft. On some bikes, you need to pry or maybe use a puller.

Your clutch lets go on hills because the motor can generate more torque than your hands.