Astrale 8 Cadence Magnet Issue


New Member
Nov 21, 2004
Hello: I installed an Astrale 8 on my ride...the crank arm is concave on the side that faces the hanger set (Trek 5000 - Bontrager crank of course)...therefore, when I try to affix the magnet with the 2-sided (worthless) tape AND the plastic zip band, the magnet just "flops around" (won't sit flush doe to the concave crank backside). I can see it pulling toward the sensor (yes, it is passing the sensor in the correct spot), but it does not register cadence. Any ideas or experience? Thanks! - S

I had a similar situation to yours, I found a piece of foam weatherstripping like you put on a door jamb, cut it to about the right size, and used it to "build up" the concave part of the crank. It has some adhesive on the back, and between it, and the nylon zip tie, I was able to make it work well.

I hope this helps.

I have heard of people using Shoe Goo to attach magnets to spokes. I think it would work here to and would help with the arm being concave. It should hold quite well but you could still pop it off if needed.
You need to build it up with something like Moriba did. Otherwise, the magnet sits inside the crank, reducing its clearance from the crank, and requiring adjustment of the sensor. The sensor sticks out farther from the chainstay sideways and is more likely to be kicked or snagged.

We folded some paper towel scraps and covered them with electrical tape before zip-tying the magnet on.