Has anyone used those little neodynium magnets you can get on ebay for their cadence sensor? Are they good enough to stay put without glue (will be on a roadbike, but probably on crappy roads).

Perfectly fine. In fact, I had great trouble in removing one such was its attraction to my pedal spindle! Whether there are variations in quality I have no idea but the two I’ve bought (from different vendors) have been fine.

Yep, mine haven’t budged an inch either.

Good news, thanks!

Yep, work a treat. Bugger to remove if you have to.

I’ve been using white board magnets liberated from the plastic coating.

Yes they are perfect 🙂

Don’t buy ones branded as cadence magnets though, just buy a load of disc neodymium magnets for the same price.

If there’s a Clas Ohlsen nearby they have packs of 10 of em for a couple of quid. Obviously make sure your pedal axle is steel though.