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(Uninformed) Cadence Question(7 posts)

(Uninformed) Cadence QuestionSteve Young
Jun 20, 2003 11:00 AM
I recently picked up a Polar 710 for my bike and have generally found it to be an excellent toy/tool for collecting bike related numbers.

I have it set up with the speed and cadence monitor. While the speed monitor has been working flawlessly, ther cadence monitor is less consistent.

It's generally pretty good but on some rides I see an interrmittant loss of reading. I think I have narrowed this down to movement of the magnet of the crankarm. Although I couldn't possibly cinch it down any tighter, it does seem to move over a few rides (say 4-5 hours total).

I know there are different types of cadence monitor, but presumably most of them run with a magnet. I vaguely recall that some pedals have a facility (slot/adaptor/whatever) to enable direct hard fastening of the magnet to the pedal.

I run ultegra SPD_SL pedals.

The question then is this. Does anyone know if I can use some Shimano specific magnet to achieve a better fastening of the magnet on the pedal (cf crank) and would this work with my polar ??

I'd also be interested in hearing from you if you think it's feasible but haven't actually tried it (in which case I will).

I realise I could go to the LBS and check it out, but just at the moment I happen to be trapped in the office and it's sunny outside so the mind is wandering a bit.


maybe a couple drops of exopy under the magnet? ..nmt0adman
Jun 20, 2003 11:16 AM
If I recall correctly...biknben
Jun 20, 2003 11:40 AM
The Cadence sensor magnet has a strip of adhesive on the back of it. The zip-tie does most of the work but th eadhesive keeps it from slipping. Did you remove the paper to expose the adhesive?

The cadence unit came with a square of rubber padding to be used between the censor and the frame. You could use a very small amount of it between the crank and the magnet. Also, double sided tape under the magnet would probably do just fine.

Some Campy pedals have a magnet built into the pedal. No need to buy new pedals for this problem.
Try thismainframe
Jun 20, 2003 11:59 AM
Purchase one of these rare earth magnets and stick it directly to the back of the pedal spindle on the inside of the crankset. No unsightly wrap around the crankarm and guaranteed to work (magnet is much stronger, distance to the sensor becomes less critical). I purchased #33516, 12.5mm. Never had a problem since and it will never fall out. I have it on both of my bikes.
Good Info! Thanks (nm)Chen2
Jun 20, 2003 12:21 PM
I took the paper off and used the adhesive pad but ..Steve Young
Jun 20, 2003 12:19 PM
I wonder if the zip tie may have reduced the effectiveness of the pad. When I cinched it down as it compressed the thin foam pad which may be some of the cause of the original problem I think.

I may try sticking a stronger magnet to the pedal as the poster below suggests - It sounds like that may increase reliability by reducing the criticallity of the distance between the pedal/crank/magnet and the sensor.


Jun 20, 2003 12:20 PM
I've used a variety of magnets glued to the pedal spindle or the crank arm. I quit using zip ties because dirt and moisture gets trapped between the tie and the crank causing corrosion and scratches on the crank. I usually use a disk shaped magnet and grind chamfer on the back side to fit the cone shape of my Speedplay pedal spindle. Then I just glue it in with Superglue. The magnet that comes with the Cateye Astrale (what I use) will usually stick to the back side of the crank arm without using the zip tie.