TDCM Installation Help

[jmwhite151]

I just finished installing the TDCM torque sensor in my Trek 4500. The instructions specify a certain orientation of the bottom bracket spindle with respect to the crank arm (see image). However, the square taper on my crank is oriented 45° differently than shown in the instructions (see other image). Is this a problem? Part of me thinks that it shouldn't make a difference. Another part of me thinks they wouldn't have specified it if it wasn't somewhat important.

If you have any experience/knowledge, please let me know. If I don't hear anything, I'll probably just go ahead and install my crank tomorrow or Monday and see what happens.

Thanks,
Jeff

 

[jmwhite151]

I contacted TDCM. Here was their reply:

We noticed your question, and the effect on sensor torque output would be either 45 degree earlier or delayed.

In your case, we would recommend that you should install your crank 45 degree forward. It is not a big problem. However, we still hope that you can chance the crank to have diamond shape.

I installed the crank 45 degrees ahead of what is shown in the manual and took it for a quick test ride. It seemed to work fine. It wasn't drawing tons of current, relative to when I give it full throttle. But I think that's probably a setting in the CA. I haven't played around with it yet. I'll keep you posted as things progress.