- Dec 9, 2003
Pelotonium said:Tom, you seem to know what you're talking about. I've worked very hard to get my PPO unit to work consistently, to no avail.
May I ask where you got your magnets, and what glue you used to bond them?
Easy...the magnets I get from my stash of "scrap" prototype samarium cobalt (rare earth) magnets in my office at work
I'm lucky to have this easy source for some REALLY strong magnets...but a quick search online should find you some sources of some pretty easily as well.
The "glue" is just DAP contact cement...the kind you get at the hardware store in the little brown bottle (with the brush built into the cap and all). I had some left over from my "heat shrink mylar" wheel cover project, and just decided to try it out. It works great. I've got some magnets that have been glued on for almost 3 years without a problem...and I've glued them to both aluminum and carbon crankarms. The nice thing is that if you need to pop them off for some reason later, the contact cement is soft enough still so that you can do it without damaging the magnet or the crankarm.
Oh yeah...here's another tip on the crank magnet, especially if you're using a "non-supplied" magnet. I discovered that the cadence sensor (a reed switch) is much more sensitive to the magnetic field "across" the poles of the magnet, rather than "in line" with the poles. In other words, don't point the north or south pole of the magnet at the sensor...align the magnet so that the N-S axis of the magnet is parallel with the centerline of the bike. You can have the magnet MUCH further away from the sensor when it's oriented this way.