I recently put one on my mtb for the reason of signal loss amongst others. Knocked the otherwise well secured magnet off my cranks in the first 00:30 minutes. Still have more accurate speed and distance info though. Distance is particularly nice if you're doing any poorly marked trails where you're looking for a particular spur at some point or performing some form of navigation. Otherwise, its mostly post ride curiousity.
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Birth Certificate, Passport, Marriage License Driver's License and Residency Permit all say I'm a Fred. I guess there's no denying it.