Cycle computer on rear wheel....am I thick?

equinefunk

Hi,

Just putting my bike on a Turbo trainer & wanted to fit the wheel sensor onto the rear wheel, I've fitted into onto the Seat Stay. It doesn't work.......Is there any reason it won't work?

It's a wired Sigma BC1606L & the wire stretch no problem, could the angle of the sensor be incorrect? It works fine on the front wheel.

Thanks in advance.

benno68

Is the sensor close enough to the magnet? You may find that there is a bigger gap from the stays to the spoke when comparing to the fork.

I've had to use an old bit of inner tube around the stay to bring the sensor closer to the magnet, this was using a Cateye wired computer with a cadence sensor which has the magnet fitted to the rear wheel.

equinefunk

thanks for the reply, no it's really close almost touching......it is really strange...I though it might be the angle of the sensor it's probably at 45 degrees on the back compared with virtually 90 degrees on the front.

ColinT2

The angle shouldn't have anything to do with it - have you tried cleaning the contact points between the computer and the mount unit (use a fine 600grade sandpaper)

benno68

Put a photo up if you can, maybe someone will have the answer.

I wouldn't have thought the angle of the sensor is an issue as long as the sensor is close enough and square on to the magnet.

The rear stays on my Defy are a good 15mm further away from the spokes that the front fork.

Hold the magnet and move it back and forth over the sensor, are you getting a reading?

ride_whenever

My bet would be either dead batteries or the magnet in the wrong place radially to move over the sensing zone...

equinefunk

Hi, thanks for the feedback....it is really strange. i put it on the front wheel & spin it & it reads out the MPH. Detach. Fix to the rear wheel & spin & nothing......

It's got new batteries is clean & square & close to the magnet. It just doesn't seem to work on the rear....

balthazar

Listen closely to the sensor as the magnet goes past. If it's functioning correctly, you should hear a small "tick" as the magnet closes the reed switch. It may be very quiet – check you can hear it by listening when it's working.

The Mechanic

It could be that the magnet is the wrong way round. I have this problem once and discovered that the magnet was only magnetic on one side.

desweller

Is it the same distance away from the hub as it would be on the front wheel?

They are inductive devices - if it's close to the hub you get a long but weak pulse, if it's near the rim you get a strong but short pulse.

equinefunk

Thanks for the feedback....I check last night & the magnet was no longer magnetic......simple, I didn't even consider that so thanks for the advice. I had a different magnet but the same style on the front wheel but never swapped them over.