Hello - I need to install the pedal sensor from my Yose Power kit, but none of the online demos seem to have the same crank hardware unless I'm missing something! So once I have the pedal off, I assume I need to take of the big round metal piece ( pictured below ) - what tool would do that? Sorry if it's a daft question.
Many thanks again.
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That's the easiest type to fit a PAS to.
Before starting, measure the gap between the pedal arm and the edge of the bearing adjuster (piece with two large dogs) and compare it with the thickness of the magnet disc. You need at least 1mm more for the gap than the disc thickness.
First remove the pedal arm with a crank extractor.
Use a large adjustable spanner to hold that bit with the two large dogs on still (bearing adjuster), while you unscrew the locking ring with a C-spanner, or tap it round with a hammer and screwdriver. It doesn't matter if the inner part with the two dogs moves as long as you put it back in the same position. It adjusts the free-play on the bottom bracket bearings, so if your crank is a bit loose, you can screw it in until the play is gone. If you unscrew it, all the ball bearings will drop out.
With the locking ring off, put the sensor in place, then reassemble the locking ring being careful not to let the bearing adjuster turn in, which will over-tighten the bearings.
Put the magnet disc on the shaft (normally with the arrow pointing backwards on that side of the bike).
Test that the PAS is working. If it only works when turning the pedals backwards, flip the magnet disc.
Before reassembling the pedal arm, you need to think about whether there was enough gap for the magnet disc. You can grind up to 3mm off the back of the pedal arm if there was insufficient gap.
Reassemble the pedal arm and check that it's not pushing the magnet disc onto the bearing adjuster's dogs. If there's not much gap, it might be worth epoxying the disc to the pedal arm to stop it drifting across.
