Cycle Computer on 36" wheel

Well, ok, I’ve searched, and can’t find the exact answers I’m looking for, hence the new thread.

I’ve got a Nimbus 36 and want to use a cycle computer. Fine. No problem. Well, except for attaching the magnet to the spokes.

I read somewhere that the use of a file is needed to get the magnet on the spokes. Maybe I’m being dumb here, but I’m assuming that it’s the magnet attachment that needs filing, and not the spokes?!?!? If not, why are the spokes so thick?

Anyway, I tried filing down the inner bits of the magnet attachment so that it would go around the spokes. Sadly though, the amount of thread left to tighten a screw up against it isn’t enough.

Am I missing something here?

Or, as inspired by some posts in a recent thread, am I thinking about things in a non-logical manner? Joe Marshal mentioned a website to convert the amount of revolutions per minute of the left crank in to a speed. As us unicyclists (non-schlumpf owners anyway!) have a fixed hub, wouldn’t this work just as well? As long as I can get the magnet and sensor within the 4mm tolerance then surely it’ll do the job?

So… obvious questions… what’s the best way to mount a magnet on an ali crank arm? I’m guessing (hoping) cable ties will be used, but not sure if there’s a better way.

I’ve also read that a single magnet on a 36" wheel isn’t necessarily the most accurate way of doing things, and that 2 magnets set up for an 18" wheel work better. So… this is impossible with the crank arm idea, right?



I had the same problem after filing. I used a little JB Weld to fasten the magnet on.

Weird. I’ve always just popped the magnet on as is. You surely shouldn’t be filing spokes.

You could probably put it on the crank, but then you’d have to mount the sensor in a place where it’s likely to get hit by your feet. I always had hassle with knocking sensors or the wire going to them on cokers, even with it in the normal place. You also have hassles when you want to change cranks to use shorter cranks down to lovely lovely 110 cranks which you probably will soon (shorter cranks = less likely to get knee pain for most people).

I stopped bothering with cycle computers in the end though, as the sensors tended to get bashed off when riding muni. If you really want to know max speed, count pedal revolutions. If you want to know average speed, the only meaningful information you can get off a map if the route and when you started and finished. I sometimes use a stopwatch on my commute to see how quick I am.



Why not just get the Garmin Forerunner 305 gps.I think that it would be so much easier.

I think Spence has a GPS already.

The advantage of cycle computers, is that you never forget them, and the batteries don’t run out (well not for a couple of years anyway). GPS is great if you don’t do more than a days riding between having access to a charger. Cycle computers are nice for keeping track of how far you’ve ridden in total, which unless you faff around with the gps on every commute and every little ride, you don’t get from a GPS.


A picture would help. I have a cateye cyclometer on mine and it was a very easy set up.

Depends on the brand. The magnet unit on Schwinn cyclometers, for example, doesn’t fit over the big spokes on a Coker. The magnet unit on Cateye cyclometers works just fine. I’ve had a Cateye Enduro for the last 3,000 miles and have been very happy with it. Happy enough that when we got our son a Nimbus 36, I went out and bought a new Cateye Enduro for him. The magnet unit fit just fine.

I have a crappy halfords 12 function and the magent fits fine, both on the old steel 12g spokes and my current stainless 14g.

Less of the crappy - I have that one, and it’s the most reliable cycle computer I’ve found. Nice fat strong cable, decent magnet (has two positions so it will sit on fat 12g or normal 14g spokes), all the features you could want. I haven’t dug up the manual to work out how to use the multi-trip odometer yet though - it’s an extra between total distance (normal odo) and latest trip distance, ideal for ‘tour distance’ etc. Total odo at 4380 miles and counting :slight_smile:

Not sure what you do to yours Joe, but a sensor on a coker frame that doesn’t get badly abused should be safe enough?


I guess it’s pretty good actually, I just had the worst halfords experience ever while buying it. I understood the three oddos were current trip, total for the wheel size preset you’re on, and total for both presets. There’s several things I’d prefer were different on it but it was dirt cheap so nevermind.

Yup. It certainly would. However, I’ve got a spare cycle computer sitting here, and I don’t have spare GPS money :smiley:

As Joe says, I do have a GPS solution, however, it’s via my mobile phone, and is far from ideal for just keeping a log of distance and max speed.


A simple solution, that probably should have been more obvious to me. I’ll give that a try. (Actually, I’ll try a hot-glue gun first, as I’ve got one of those to hand. Should do the trick just as well)