Why is my electric bike 'clanking' under load? I have a Giant Esprit Twist Power electric bike, which apart from not having nearly enough words in its name also has a problem related to the crank.

When I put a lot of load through the pedals there is a loud clanking sound, once per pedal-press. If, as I cycle, I press with just one foot (and just lightly follow-through with the other) then I get the noise once and then not again until I start pressing with the other foot. This suggests to me that the problem is related to something shifting position in response to the side of the bike on which the pedalling force occurs.

Curiously, although the noise is extremely pronounced, I don't think I can feel anything.

There is no play I can feel in the bottom bracket, and likewise the pedals seem to spin smoothly.

The torque-sensing chainset arrangement seems like a possible source for the noise, I'm just not sure how.

So I guess my questions are...


Can a bottom bracket bearing make this kind of noise without feeling rough or loose?
Does anyone have any advice to offer about this kind of torque plate?


Here is a picture of the dismantled torque-plate:



Thanks in advance!
That crank is unusual and therefore it is hard to give you advice.

It shouldn't be the bearings because they don't usually make a big noise, but
rather make the crank harder to move around (you can perfectly feel bad bearings if you try moving it with your hand and feel resistance/side-to-side movement).

Can you install the crank without the clutch mechanism, or simply install another crank, and test if the noise goes away? My bet is it will :)

If the noise goes away, the best is to contact Giant support or a representative and see what they can do for you (send you new pieces, help troubleshooting, etc). If they can't do anything for you, at least ask them to advise on a solution, or to suggest a list of cranks that are compatible with the electric system, in case a normal crank does not work.

While testing keep in mind this can be a malfunction piece which might fail to perform at the worst possible moment, so take it easy. Good luck.