I just bought an SI-90 wireless computer for my MTB, only to find that (duh) there was no way I was going get the magnet anywhere near the wireless reader on the fork. After kicking myself for a minute, I remembered I had some rare-earth magnets on my fridge (long story...). Sticking two of those on the provided spoke magnet brought them close enough (perhaps 6-8mm away rather than the recommended 2-4mm) that the computer started reading speed. These are crazy-strong magnets, so I'm worried about two things: will this affect my readings (perhaps by having a much longer period in which the magnet is "seen" by the reader), and is this going to damage my computer and/or spoke? My understanding is that it's basically counting the time between hits of the spoke, so it should be ok, I think, but I don't know.