computer sensor mounting Qs

erknjerk4w said:

I bought a Bell SpinFit and it does not mention how far away from the hub to mount the sensor and magnet. Does it matter?

It doesn't matter really, as long as the sensor and the magnet can line up close enough to get a signal. On my bikes I use the slide on magnet and I attach it right at the rim where the bladed spokes are round. I then mount the sensor right below the brake pads. Nice and compact and close enough so I don't have to worry about the wireless computer not picking up the signal

Thanks for the input Peter.

I mount it right near the hub so there is less rotational inertia, and it can get a better reading, more time to pick up the magnet.

bobbyOCR said:

I mount it right near the hub so there is less rotational inertia, and it can get a better reading, more time to pick up the magnet.

thanks I got it pretty close to the hub now.

bobbyOCR said:

I mount it right near the hub so there is less rotational inertia, and it can get a better reading, more time to pick up the magnet.

Good point, it will pass the sensor at a slower rate this way. With my Polar 725 the sensor is so big, that I hate how it looks at the end of the fork, plus it's wireless and the base unit needs to be inside a certain distance to pick up the sensor readings. The shape of the fork helps too. On my older bike (cromoly fork), it always worked better down near the hub.

I have not yet, but am intending to fit a wired computer with the wire running down the inside of the steerer tube.

This would be achieved by mounting the computer on the stem, repacing the star washer with a USE Ring-go-star thingy, routing the wire through the steerer and down the inside of the fork leg.

This would give the reliability of a wired computer with the uncluttered finish of a wireless. It would actualy look better than a wireless as wired sensors are smaller and neeter.

What do you think? has anyone tried this already?

I am not sure how good the Ring-go-star is so has anyone found a steerer bung/star washer which would alow a wire through?

PeterF said:

Good point, it will pass the sensor at a slower rate this way. .

Ummmm, it won't matter where you put the magnet. It will pass the sensor at the same rate. After all, it is a wheel. The hub doesn't turn at a different rate than the rest of the wheel. IE. if the hub turns once, the rest of the wheel turns once.

remdog said:

Ummmm, it won't matter where you put the magnet. It will pass the sensor at the same rate. After all, it is a wheel. The hub doesn't turn at a different rate than the rest of the wheel. IE. if the hub turns once, the rest of the wheel turns once.

You are thinking about RPM's, not speed. The outside of the wheel is moving faster than the hub because it is traveling a farther distance per any given time.