I currently use a typical bike computer with the sensor on the fork and the magnet on the spoke while also using a GPS app on my phone. I've ridden 25,000 miles in 4 years and all miles were logged. The bike computer comes in handy to give me distance when I ride my rollers inside. I'm thinking about upgrading to a GPS bike computer that is ANT+ and Bluetooth capable. My problem is this: I will be riding my rollers and the GPS unit will be worthless. I'm thinking an ANT+ speed sensor added on my bike will display speed and distance? I want the distance to show up as well as the speed because I log all miles. However, looking at all the info on speed/cadence sensors one is to believe they don't track distance? I even saw a YouTube video of someone setting it up and speed and cadence were displaying, but not distance! Do speed/cadence sensors display distance too? Thanks!

The sensor just measures how many times your wheel goes around. It's up to the head unit (or app) to turn that into distance.

Most Garmins have an "indoor" mode that will do what you want. Some people use those indoor "miles" for maintenance, eg lube your chain every 100 miles or whatever.

Yes, but it depends on the specific unit.

I have a Lezyne Super GPS that does bluetooth and ANT+, and if paired to speed cadence sensors will track distance on trainer rides. I think most of the Garmins will too but you'll have to check the individual model.

I have Garmin speed/cadence sensors for the rear wheel on all my bikes. Works fine, you just have to remember to push the start button on the device. Of course they track distance, time, etc.

The Lezyne Super GPS is the GPS unit I am looking at! So if I buy a compatible speed sensor that is listed on their site I would be able to track my distance indoors?

Works for me. I've been using the Wahoo Speed/cadence sensor but anything that tracks your distance by revolutions should work.

Nice thing about the GPS units is that if your sensor goes dead during a ride it will revert to tracking your position and speed through GPS, so you don't totally lose data for that ride.

I have a Garmin Edge 520 and use the ANT speed sensor on the rear wheel, and a cadence sensor on the crank arm.
It works fine for measuring/displaying speed and distance while riding on indoor rollers and stationary trainer.

I think that's the only purpose of the wheel sensor, right? It works outside too if I forget to turn the GPS back on, but I assume when I have GPS on, the head unit is using that to measure speed/distance and not the rear wheel. Hmm...

Sounds like a speed sensor will communicate distance to the Lezyne Super GPS, as long as it's one of the sensors that are listed as compatible. Thanks!

Thank you everyone!

I don't know exactly how the Garmin units work. I emailed Lezyne and they said it tracks distance with the sensor if it's connected, but if it loses connection it will revert to GPS. So I still had to mess around with the wheel diameter numbers to get it accurate.

As an additional point of info, when I sync rides to Strava, Strava uses the actual distance and speed info from the GPS data, and does not use the speed/distance from the sensor. Which is nice on those rides when the sensors fail or get interference from someone else's sensors, at least I still have accurate data.

On a Garmin it uses in this order: power meter, ANT+ wheel sensor, GPS. My Edge has a setting (Automatic) which causes the device to calculate the correct tire size using the GPS. Thus if you're riding in thick forest or along cliffs, it keep track of your distance correctly even if it loses its satellites temporarily.

So ksryder, if you use your sensor indoors and after the ride you want to enter the data to Strava, it doesn't sync the miles from the sensor? You have to enter the data manually to Strava? If so, that's not a deal breaker, that's what I do now. It would be nice if it uploaded data whether it was from GPS or a sensor..... Let me know!

You can set the preference in the Garmin settings for how speed/distance will be prioritized-- I have it set to speed sensor first, then GPS. In mountainous areas, GPS accuracy drops off really quick. For best results on a trainer/rollers, you just have to be sure to set the Garmin to Indoor mode (if you have a newer unit that has that mode) or you'll get a crazy, squiggly ride plot with all kinds of speed jumps as the GPS keeps trying to locate satellites-- indoor mode just disables the GPS and goes from the sensor only. This also leads to insane battery life-- even with the backlight set to always on, my 520 went about 2 weeks of use on one charge. My "workout area" is right in my workshop, which is a steel truss metal outbuilding, so GPS simply cannot get inside. Oddly, I get the weirdest speed readings on the road with the sensor on the rear wheel, but it works fine indoors-- never drops out.

On the Lezyne, if you turn off GPS for your trainer rides, Strava uses the speed sensor data to compute speed and distance. Here's an example: https://www.strava.com/activities/762684883

I didn't have to edit anything other than the activity name after the ride was uploaded.

No it automatically uploads trainer rides with distance, and syncs to strava.

Strava will use the distance data supplied by the bike computer, but if there is *also* GPS data it will default to that for the distance/time/speed figures. I don't turn the GPS off for trainer rides; it figures it out anyway.

Thanks for sharing your personal experience with the Lezyne Super GPS!