I had a challenge mounting the cadence magnet on my recumbent. But I believe this could also be a problem for DF bikes as well. The problem is mounting the magnet on a crank arm that is hollowed out on the backside (which is where the magnet must be located).

The solution is to use a product called "Sugru". It's a silicone based putty that sticks to just about anything and can be sized and molded to whatever purpose you may have. It has an infinite number of uses. Once it cures, it retains its shape permanently.

thx for the link. that stuff has possibilities.

Consider moving it to the inner chainring on top of one of the mounting bolts (assuming the bolts are slightly recessed into the chainring). It won't get knocked around nearly as often.

Not a bad idea but it's contigent on your inner chainring boltheads as you mentioned. I looked at mine and the boltheads are raised. Since you also have a Slipstream I can only guess your bolts are recessed. I would also think you needed an extension to get the sensor within range of the magnet (just as I did). That whole area around the crank is a bit cramped.

I should add that the Sugru works well for this application.