i recent bought a new bike and the chain stays are curved in which places my catee v3 at a little wider angle than it used to be so my cadence is only working sporatically. i have the magnet simply "attached" to the back of the pedal because that is the position that puts its the closest to the reciever. the instructions say that it should be 3mm, but mine is more like 5-6mm.

Is there a thicker magnet out there i can use, or can i double up on the magnets to decrease the gap to the proper specs? i would like one thicker magnet instead of two jsut because it is not attached in any other way that being simply magnetized to the back of the pedal axle and it would be less likely to be lost

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I had a similar issue on my Giant carbon frame and my Garmin sensors.

What I ended up doing is mounting the cadence/speed sensor upside down and backwards. Careful adjustment then allowed the cadence and speed magnets to work properly and allow the speed arm of the sending unit to clear the spokes.

To get the cadence working (which was more important seeing as how speed is measured by the GPS anyway) I had to put the flat rubber spacers that came with the gps under the cadence magnet. The spacer lifts the magnet just enough to make everything work, but not too much that the magnet hits the sensor.

Clearance tolerance is very tight, I am probably only 1 or 2 mm max from anything else.

I had to fiddle around with adjustments for at least an hour.

I've always wondered why the cadence sensor also does speed, when it only works with a GPS which is measuring your speed anyway. On the other hand, it has the speed written into your GPX file, so if you wanted to do anything in software that wasn't able to recalculate it, that could be a bonus. But how many people actually need to do that...?

Anyway, apart from your trouble getting it set up with your bike frame, how do you like the Garmin cadence sensor? I was thinking about picking one up myself. I've got an Oregon, and a mount to get it on my handle bars, so I've been appreciating it as a heart rate monitor and bike computer. Seems like cadence is the next thing I should be aware of...

Have you thought about using a small piece of foam double-stick mounting tape under the magnet?

The speed sensor is included for a couple of reasons. First off, you still get speed even when not really moving, as on a trainer. You also get speed even with a poor lock or no signal at all (possible in a canyon). Lastly, if you do not need your position you can save battery power by turning the GPS off and just using the wheel sensor.

As for function, once I adjusted it all it works great. Cadence works, speed sensor works, the spokes clear the sensor, and all is well. The odd shaped chain stays did present a slight challenge, but at the worst you would just not have the speed sensor - which is not a problem except for maybe riding on a trainer.

My Sigma computer came with a shim for the cadence magnet to accomplish just this, but I'd think the good quality double stick mounting tape (the thick stuff) would work just as well. Good idea...

I stole one of the magnets out my my kids Magnetix set. Each piece has two magnets and are super powerful for their size. They don't have to be as close to the sensor as the stock magnets do. $12 gives you over 100 little magnets.

Those are cool. I glued one to my crankarm because I kept bumping the regular zip-tied magnet with my heel and knocking it out of alignment.

Bluechip's idea looks good, too.

I mounted mine on a Carbon Cervelo and also did it upside down. It just seemed to fit better (closer) in the that position. It took some time to adjust but works fine.

I now have the Shimano Speed Deck and the Garmin on the same bike. Yes it looks a little fred but I have no intentions of removing the Speed Deck since it shows gear position and provides a separate readout.

The readout from both devices are very close on speed but the cadence is off. The Speed Deck read 10 higher (80 vs 90) and I wonder why? Yes the Shimano computes cadence but I think all of the gear information is correct.