Any reason that I can't mount my speed sensor that's one the front wheel on the rear if I can find a place for it to fit well ?? I can't think of any reason why I can't

Only reason would be if it is wired and the wire isn't long enough or if it is wireless and the computer won't receive the signal.

Well I'll have to give it a try. thanks

A lot of computers have a rear-wheel sensor option, longer cable for wired type. I got one one for an old Cateye for riding my trainer (not rollers, which work fine front-mount). I suspect that digital wireless systems should be front or rear-sensor compatible. You can always contact mfrs to find out.

You can also try GPS, which has a little lag, and sometimes under-records your maximum speed (if you don't hold it long enough), but it's pretty good.

Wireless has to be 'line of sight' mounted, correct?

Only reason would be that it doesn't function correctly or reliably when placed in the location you choose. Try it and see.

Some do, some don't, depends on the computer.

I see what you're trying to do here. You're going to mount the sensor on your rear wheel so you can put the bike on the stand, crank up the wheels, and then fake the speed and mileage eh?

I don't like this. Not one bit.

I must confess though, I recently used endomondo on a 300 mile drive. I averaged 75mph and burned close to 20,000 calories.

Depends on the computer. My Sigma didn't pick up the sensor (mounted on chainstay) while in the standard stem position. I had to move the computer to the top tube to get them to connect to each other.

Only reason I did this is so I get readings while on the trainer.

/\ +1

Only useful if a power meter is used for rough calibration.

As for wireless, that depends on the manufacturer & model. For example, my Polar CS-200 would not work with the speed sensor mounted on the rear (range limitation) but it works fine with the CS-600 model.

This certainly explains why so many people post garmin stats without power data.

I just want to keep track of the mileage on my gear while I'm using the trainer over the winter.
and w/ my Rox 8.0 and the speed sensor location on the rear chain stay next to the cadence sensor works just fine.

Mine wont work on rear wheel? Don't know if it's distance or line of sight

Lot's of ANT+ and similar senders and receivers don't work well between the rear wheel and the handlebar. Distance is certainly part of it, line of sight could be too. Try it and find out is all you can do. You don't have to mount it, just mount the magnet on the rear wheel, hold the sensor near the rear wheel, and spin it. You will know pretty quickly if it works. You might want to look at RNAV's thread about his Trek built in rear-wheel sensor not working well with his Garmin: https://www.bikeforums.net/road-cycli...ep-inside.html. Even system made to work from the rear wheel often don't.

The signal just takes 4 1/2 years to get to your head unit.

A lot of the wireless computers won't pick up the signal over the added distance. The bluetooth ones that work with the Iphone or android phone usually will.

Just use this speed sensor and you can put it on either wheel:

https://www.amazon.com/Garmin-Bike-Sp.../dp/B00JM6DKUA