I want to start using my trainer again and forgot how to set up my Garmin 705 to track speed. I remember that I needed to set something in the 705 so that it will use wheel size rather than GPS to determine speed but I can't find it in the owner's manual.

Does anyone remember what I need to do in order to display speed while on a trainer?

Thanks

You need the GSC-10 sensor.

see simon's post

Yes, I have one and it is working. It is showing cadence while on the trainer but not speed.

do you have the magnet on your spoke and is it close enough to the sensor?

Yes, it almost touching the the sensor. Probably about 1/8" away from the sensor. I thought that there was a setting I needed to check in the 705 in order to get it work on a trainer. I have used it on my trainer before but it was more than a year ago.

If you're getting cadence it's correctly paired. I'd verify that the magnet is aligned with the line on the speed sensor arm. Failing that I'd replace the battery. If all else fails your sensor may be toast.

It sounds like a dead battery, When the battery gets low, speed quits working before cadence

I think you might be right. I just changed the battery but I think the battery is bad. Even though I am getting cadence readings, they are jumping around which probably means the battery is dead. I will buy a new battery and try again.