I read on another forum that when mating a Garmin 800 with a speed/cadence sesnor that you enter the wheel size in the Garmin. I find no way to do that. There is no prompt. It makes sense that it would be required since most bike computers require wheel circumference be entered. Was the information incorrect? If not how do I enter it? Please, if you know nothing about a G800 please don't hazard a guess.

The Garmin GPS units I've used will automatically calculate a wheel circumference after it's been used with the speed sensor for a little while.

I have an Edge 800. Here's how to set the wheel size:

1. Start the computer
2. When the computer starts up, tap MENU then the small wrench in the bottom right corner
3. Tap Bike Settings then Bike Profiles
4. Tap the profile for the bike, then tap Bike Details
5 Tap Wheel Size than Automatic or Manual.

If you select Automatic, it will use GPS to determine you wheel size.

If you select Manual, enter the wheel size.

thank you very much. It is now set to manual. I measured wheel circumference by rolling the wheel on a tape measure and converting inches to mm. I figure that is the most accurate way. Came out 2153. Tires are 32mm.