Sorry, I was wrong, I corrected my post. Accelerometer in the phone doesn't use magnetic fields to detect motion. I confused the function with motion capture sensors which contain a combination of other types of sensors.

Anyway, there is a chance that the magnetless sensors sometimes gives occasional false readings from bumpy roads. You could look at threads and blogs reviewing them. Although overall, I don't think the errors would significantly change the total distance and average speed. You might get some spikes though. I decided to stick to the old CooSpo model that uses a magnet for a more conventional and less error-prone mechanism, and less likelihood of false activation when not riding the bike.

One benefit of the magnetless sensors is the ability to quickly remove and reinstall them with the rubber band without needing to adjust a magnet. Some reviews say the rubber band breaks and they lose the sensor, while others say it's fine. You could use zip ties instead, but then it's no longer easily removable.

Oh, and if you still want to try a magnetless sensor and are worried about them falling off the hub or crank arm and losing them, you could try some cheap Magene sensors from Aliexpress, which are around $12 each. You could look around the forum for feedback about Magene. The newest version is the S3+, which supposedly has a new geomagnetic sensor, whatever it means. The old version found on Amazon is the Gemini 200 or 210. The only difference in appearance is the sticker on the back of the battery cap, so you would never know if it was the old model with a new label.

Ended up with Wahoo. Found the Bolt for $180 and the sensors for $56. So not the $150 I wanted to spend, but $236 for Bolt + Speed + Cadence doesn't seem like a bad deal.

Great deal on all. Have fun with all.

Any suggestions on how to open the Wahoo sensors without damaging them? They are assembled so tightly that trying to pry it open just seems to damage the casing.

You still did well. I hope you enjoy them!

Can't remember if I had that issue when my sensors were new but they should just pop open when prying in the provided slot. I've used screwdrivers and even butter knives without a problem.

Wait...are you guys talking about the Wahoo wireless sensors? They have a battery compartment on the bottom that you use a nickel or quarter to turn and open. You don't pop anything off.

Not on what I am using. They have a little ridge on the side for prying them open. They just seem so snug that I am risking damaging them to get them to open.

Yes! The Wahoo magnetless sensors. They have a slot on one end that you can use a nickle, a quarter, a screwdriver or butterknife to separate (or pop) the two halves apart to change the battery.