I just purchased a cateye strada cadence rd 200 for my Surly LHT and I am mounting sensor and magnet on rear. Does the gap have to be less than 3mm like the instructions say? Even with the spacer they send with it the gap is way more than 3mm. Should I just keep using more spacers? For the cadence sensor on crank is still more than 3mm but should be easier to adjust to get closer. Any ideas and did anyone else have this problem? If it works with a wider gap should I just leave it as is? Or does that throw off calibration?:(

I have the same problem on my Surly LHT and a friend has it on a Giant Cypress, so it's not just the Surly's. I haven't kludged a good fix for it yet, but I haven't made it a priority right now. My friend was given some suggestions by the LBS. One was to shim the sensor with a piece of wood. Sounds like a good idea until he rides in the rain (we live in the Pacific NW, it's always raining) and the wood gets wet. The wood would either swell and possibly break the tie wraps or would get wet and hold that moisture next to the metal of the chainstay. We talked about it and pretty much chucked that idea into the trash.

We're both engineers with more ideas than time and what we came up with was:

use an old inner tube to shim either or both the magnet or sensor to get them close enough to reliably read cadence

-or-

Use a piece of high density closed cell foam to shim the magnet for really big gaps

-or-

use a very expensive and powerful magnet on the pedal which would allow for a bigger gap. You can get one of these magnets if you tear apart an old hard drive. The magnets in those will knock your socks off.

As to the effect of the gap? I would imagine that having the gap be larger than 3mm, with the standard magnet, would mean that the sensor may not pick up the presence of the magnet on every pass and the computer will interpret that as either a lower cadence or intermittent readings. I've had sensors work with more than 3 mm gap, so if yours is reliable at a bigger gap, you should be ok. If you start getting readings that are obviously wrong, you'll need to reduce that gap some more.

Let us know if you find a really elegant solution. I'll do the same if I ever get around to really monkeying with it. BTW, don't you just love your Surly? I just love mine :love:

I have a Surly CrossCheck and ran into the same problem installing a Cateye Strada. I just used thick rubber pieces to shim the sensor like sparky mentioned. Interesting idea about using stronger magnets by the way. I just so happen to know a good place to get those ;) Check mcmaster.com and search for samarium-cobalt magnets; those are insanely strong.