I’ve never had such a temperamental bike computer and it’s driving me nuts!

Anyone else used on of these? It’s on a road bike so not a huge distance between the sensor and computer. Everything is set-up as per the instructions. I put new batteries in last week.

One day it works, the next it doesn’t. I pair the computer/sensor and it works again. Then it doesn’t. Is it just me being an idiot, have I got a duff one, or are they just a bit iffy?

Thanks