I installed a Cateye Mity on my road bike in 1993 or '94, and except for two battery changes since then it has been very reliable up to this year. This year the few rides I took on my road bike I noticed I had to wiggle the head of the computer to get it to read - I suspect there might be a problem with the connections or wires, and I prolly can't get parts for the 20 year old computers, though.

I did win a new Sigma Sport wireless in a draw at a mtb race this fall and I have that on my commuter bike. I ride my commuter bike through a nuclear waste dump twice a day and get no interference. I suspect the *ahem* affordable Bell computers aren't the same quality.

Not to worry, the current wired handlebar mounts will work with your old cyclometer head. Also, I find that cleaning the contacts with a pencil eraser to scrub off the crud followed by a dab of silicone grease restores the reliability.

That sounds cool. Does it also have separate odo functions in addition to the total? I like to keep track of mileage on each bike, like car odometers, but having a total number is nice, too.

The ticker in my sig is total miles ridden on both bikes since I started back riding the 1st of May.

No, there is just one cumulative odometer function on these Cat-Eyes. They do have a two separately resetable trip distance functions that could each be dedicated to one bike (and wheel diameter) but the trip distances have a 1,000 mile maximum and go back to 0 after that. The cumulative odometer will read up to 99,999 miles.

Well looks like a wired computer is going to be mandatory now. I discovered that my new Cygolite Expilion 700 renders my wireless computer completely inoperative. Light off, works fine. Light on, speedometer just stays on 0 mph while riding.

Darn, I liked not having the wire. Oh well.

ANT+ is virtually immune to interference. You might consider an ANT+ wireless computer: Bontrager Node, some Cateye and Mavics, and of course Garmin.. There are others as well. A Garmin and Node that I have specifically work fine alongside the Exp 700.

I just discovered yesterday that my Cygolite on daytime flash/strobe mode is what makes my wireless computer (still using wireless on the KHS) go wonky. When the light is on steady, the computer works just fine. Seems a little weird that the flash mode of the light causes all that interference but the light on steady does not.

I've heard ancient burial grounds can mess with electronics something fierce.

Well, a flashing light involves a current that keeps changing, whereas one that's constantly on is powered by a steady current. You need a variation in the primary current to induce a secondary current in another conductor that's not connected electrically to the first one. The primary conductor is in the light in this case, and the secondary one is in the computer.

+1 On lightly 'sanding' the contact points in the cradle - they often develop a layer of crud/oxidisation which can be easily removed by a 'rough' (sometimes grey-coloured) pencil eraser or a very light grit sandpaper.

Also, the Bell computers, although cheap, often are *exactly* the same as more expensive models, just branded differently.

You can often fix this problem by moving the light away from the computer.

You might try wrapping the light in aluminum foil. This makes a Faraday Cage and might be enough to keep the RF energy contained within.

It would work better to wrap the computer, but that isn't an option, since you need to let a signal in.

If the foil works,you can experiment to find out how little and where to place it to make a shield without wrapping the entire light.

Not really possible the way the handlebars, tape, controls, etc are set up on both of my bikes. On both bikes the computer mount must sit directly adjacent to the stem. On my MTB I have the light mount rigged up to the stem itself, and on the road bike it's on the other side of the stem.

re: cleaning electrical contacts... DO NOT SAND THEM. use a pink soft pencil eraser. sanding will strip off any remaining anti-oxidation coating (gold, chrome, etc), and while it might work short term, it will corrode up even faster. pencil erasers do a fantastic job of removing just the oxide.

Ooh - good catch.

I'm pretty sure the contacts on my £4 Aldi bike computer are just steel, so at least no harm done there.

I seriously doubt ANY electrical contacts are steel, it makes a lousy conductor. more likely, they are chrome or nickle plated brass

Yes, outside RF interference, most likely the cause...
I've heard also that supposedly, Some Mavic Mektonic group users in the 90's supposedly had problems with their remote controlled RDs shifting themselves when riding near or under signal towers and high tension wires..... It all comes down to how well the equipment is shielded from stray signals or how the signals are designed to be proprietary to the equipment.

Chombi

I built a couple of V/T amplifiers with carbon fibre casework and as part of the development measured the conductivity and RF shielding of the casework, both of which were surprisingly high. I assume this is down to having enough fibre to fibre contact to ensure a conductive path. This was wet layup CF but I'd expect the same effect to be present with prepreg.

No it's surprisingly common to make electrical parts of steel, often with copper plate and solder finish. Many power resistors are made this way, you have to go out of your way to find ones with copper leads. The reason is that steel is a worse conductor of heat than it is of electricity, so for a small reductuion in circuit efficiency you gain some reliability- the leads won't be as prone to conducting enough heat to melt the solder that attaches them to the PCB. Of course it's also much cheaper than copper.

The intersection of "good conductor" and "good spring" is quite small and mostly expensive (eg beryllium copper).

Try wrapping your bike fork, frame and helmet in aluminum foil. Won't solve your computer problem but will look cool.

put a metal colander over it, and wear one, too.
no weird rf signals, and no voices, either.