Bicycle Mechanics - Computer does not fit/work.
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Got my Gemini 1000 today so I thought I'd install the CatEye cordless computer that I had fitted on my Cannondale road bike. Installing the computer on the bars is no problem. The sensor on the front wheel does not fit as well as the road bike, but I do notice there is a slight gap between the spokes where the cross over. On my road bike, the spokes that crossed over actually touched each other so I could fit the pickup correctly. My pickup is of the type where it fits across two spokes.
The transmitter though is a problem. The distance between the pickup and the transmitter has to be around 3mm. On my road bike, this was not a problem as the rigid forks were thinner and flatter so getting the pickup and transmitter correctly aligned was not a problem. On my Gemini, however, I tried fitting it to the front shock, but because of the size of the tubes, I can't fit the transmitter to be parallel with the pickup so that it keeps the distance within the 3mm spec. In fact, the parallel distance is about 2cm and it does not work so far apart.
It can only be aligned and will pickup if I put the transmitter at a sharp angle to the pickup and that affects the sensitivity. The computer only works providing it is less than 18" or so from the transmitter. The distance to the bars is about 24", but it's not much different to my old road bike. Those are the facts.
1. Are there computers designed specifically for mountain bikes? That is, they take the shape of the fork into account.
2. Does it mean I have to go back to a cord computer? I'd like not to if just to avoid cable clutter.
3. If I need to buy a new one, can you guys suggest some to me? I'm more familiar with CatEye so I'd like to stick with those.
Thanks in advance.
Guys, I'm pretty well desperate for a reply to my questions as I want to move soon on the computer issue before the coming weekend. If you could help me, I'd be really thankful.
On my knees, hands clasped pleadingly!:)
08-26-02, 08:21 PM
I am not familiar with this particular computer, but I can throw out some ideas that you might try.
The part that goes on the spoke is generally just a little magnet. A magnet for any computer may work. See if your LBS has any little generic magnets that will clamp onto a single spoke. I have used a couple of different kinds with my Sigma. Anything seems to work. A Sigma magnet is nice and small if they have them.
To get the magnet closer to the pickup, move the magnet down the spoke and the pickup down the fork to a point closer to the hub where the spokes pass closer to the fork. As far as I know it is not necessary to have the magnet and pickup parallel; they just have to be close enough for the pickup to sense the magnetic field. Likewise, exact vertical location is not critical since the computer is only counting the number of times the magnet passes the pickup.
Hope some of this helps.
Raymond, tks for the advice. The magnet I have fits between two spokes, so there is little room to move it. What I'll do today is get to the lbs and see if they sell separate single-spoke magnets like you suggest. I might also be able to get a longer screw for the sensor/transmitter and that'll give me some room to fit a spacer to move the sensor close to the wheel without affecting the mount on the fork leg. I'll try all this at the lbs. The problem though is whether the computer will receive the signal. I looked at the online pdf for the computer and it's ok to use it up to 45cm away so it should work. I'll also replace the battery. Hopefully, I'll get all this resolved at the lbs, who being typical of the breed, are very helpful folk.
Follow up. Saw the lbs this afternoon. They very kindly ripped open a new CatEye cordless and gave me the spacer and a longer screw to get the desired offset from the fork and closer proximity to the wheel. Still no joy though.
Local jewellers confirmed the battery is still 100% ok - it's nice to go somewhere where they don't try and sell you something just because you are in the shop.
Back to the lbs for another try. We fit it onto another Gemini and find that the distance between where we have to fit the sensor and magnet and where the computer fits on the bars is never going to be less than 60cm. Spec range is not greater than 45cm. It works if we hold the computer around the 40cm mark and less. So it seems it is just a distance thing.
Surely there must be another Gemini owner out there who has fitted a computer? If so, what type? Problems?
08-27-02, 09:41 AM
Bokkie - trash the cordless. They are way too tempramental. The transmitter needs to "see" the receiver. They eat batteries.
Get a vanilla flavoured Halfords or Cateye Mity 3 wired computer.
Sacrelege on your gleaming new bike, maybe.
Cheap, hassle free. Not so pretty, but its thin wire, and some neat cable ties keeps everything in place
Stew, I agree. The fork stanchions look a bit 'busy' now what with the cable for the disk brake tied onto them. Another cable? What the heck! Why not?:)
Apart from a problem I added to the bike mechanics forum, the Gemini is one heck of a bike. It is a stunning bike to look at and if there no other problems I'll be doing a formal running-in on Sunday. That's why I'd like to get the computer thing sorted out.
08-27-02, 09:54 AM
another thought Bokkie -
Test if the fault is definately at the magnet/pickup interface by putting your ear by the pick up and rotate the magnet back and forth past it. You'll hear the "tick" as the magnet pulls on the sensor in the pickup.
No noise then its definitely the distance and position of the magnet and pickup that you have to fiddle with.
If you can hear the tick, then you know the magnet/pickup interface is OK so the problem is between the pickup and the computer.
Remove the computer from the bars and hold it closer, and in line of sight of the pickup. Spin the wheel. if you get a reading then computer is in a blind spot when its on the bars. No reading? then the fault is either:
battery in transmitter. battery in computer. bad transmitter. bad computer.
By the time you've figured this out you could have sprung 12 quid for a manky halfords computer!!
I've tried that. I can hear the 'tick' when the magnet passes over the sensor, and the computer works when it's no more than 40cm from the sensor thereabouts. What I forgot to do, was get the shop to check the battery in the computer (the one in the sensor is ok).
I could reduce the distance by mounting the sensor at the top of the fork. That would close the distance to about 30cm but the problem then, is that the magnet would be too close to the rim of the tire, and so would still be about 2cm too far away from the sensor.
Interestingly, the cable ties for the disc brake cable clip are mounted at the top of the fork. I'm not sure if that's a good place for them, as they'd get wrecked if I ever fully compress the fork - but I don't think that will be a problem in my case.
It looks like a cable computer is the only option at the moment.
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