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Bicycle computer lead extension

Discussion in 'Riding Gear and Bike Accessories/Parts' started by vOOdsy, Aug 24, 2005.

  1. Going to install a bicycle computer (BC-800) onto my Spada this weekend.

    Was wondering does anyone know how to extend the cable/lead so that it can wrap around the forks properly. Is it a case of going to Jaycar/Dick Smiths and getting the matching wires, using wire strippers and just taping the connections together??

  2. Talk to Deafwish, he's done it already and knows all the wrinkles!
  3. get the soldering iron out fella :wink:

    OR - get a speedo with a cable long enuff....

    OR - get a wireless one :D

    but yeah, easy as just cutting the wires and soldering a new section in. i've had to do it before on a pushy when i ripped the cable to bits in a stack....
  4. ok this is kinda a hijack...
    what is this bicycle computer thing? i keep hearing people saying theyre gonna put a bike computer on but i have no idea what for... what use is it? so you know how many calories worth of fuel youre burning? :? :oops:
  5. various reasons i guess...

    maybe got a busted speedo and want a cheap fix?
    maybe trying cut down weight by removing the cluster?
    maybe got a fighter and dont want an original cluster?
    maybe just want a neato electronic speedo aswell as the stock one?
  6. ah cool. thanks! i see now. does it pass rego and stuff if you have the bike computer? and do all of them go fast enough? i havent seen a bicycle doing 110 km/h recently :p
  7. Thx for the replies :wink:

    Pt: The reason I'm putting one on is because the bicycle computer has other added function like trip meters, avg speed and clock :D

    My Spada has only got a tacho, odo and speedo.
  8. there we go, i missed a reason there too :LOL:

    i beleive it WILL pass an RWC because its not a safety item. i've seen bikes for sale that use them and come with an RWC so thats good enuff for me. and quite a lot of the better speedos actually go up to 300kph these days, and did you watch the cycling at the olympics? :shock: you can go over 110kph on a pushy, i wouldn't tho :LOL:
  9. Make sure you get a bicycle computer that is capable of motorbike speeds. Most are only rated to 80km/h, which will be useless to you.
  10. Dont know about the 80km rating... You must be looking at very cheapo units...

    And even if it is only rated to 80... it is for a spada! :LOL:
  11. The BC-800 is made by Sigma Sport and is good to 300 km/h. http://www.sigmasport.com has the various accessories etc. I think that there is an extension lead.

    I have this unit and it's been reliable up until recently. Last weekend on a ride it was moving all over the place, and at one time suggested that I was doing 356 km/h. I first thought that the sensor's playing up, but if it's max is 300, and it's reading over that, then it's probably stuffed. Might have moisture in it or something.


    As accurate as a GPS once calibrated. More so than a stock OEM speedo.

    Has trip computer functions.

    Has a clock

    Allows for a second or third trip meter.


    Not easily mounted on bikes. Designed to go around cycle handlebars, not upper triple clamps. Usually means gluing or similar.

    Not lit up for night time riding. That's an extra accessory and looks crappy.

    Fiddly mounting, given that bike wheels don't have the same size spokes as pushbikes.

    My setup uses a rare earth magnet glued using Locktite to the inner hub of one of the front discs and a couple of skinny cable ties around the sensor and the fork.

    Means a crappy looking cable running up the fork, unless you have one long enough to follow the speedo cable or brake hose or whatever your bike's got.

    But for $40 or thereabouts, it's a cheap solution to an inaccurate speedo problem and you get a trip computer into the bargain.
  12. I believe it wont meet the ADR's ;)
  13. The following applies to a Cateye Velo but would also work using only a few mods with the BC800 - the best approach is bit fiddly, but here you go ....

    You'll need:

    The computer
    Soldering Iron
    Wire cutters
    Small powerful ("rare earth") magnet (optional)
    Small drill biits
    Cable ties, heatshrink or insulating tape.

    1. Get some fine figure-8 cable that will reach the full length from computer mount to wherever you want to mount the sensor. Dick Smith,Radio Parts, Jaycar etc etc - although I scrounged mine from an old dead plugpack.

    2. Examine the computer mount carefully - there are 2 small metal clips immediately above the spots where the existing wire is terminated. These are IDC's (insulation displacement connectors). Carefully remove them from the top - they will lift out with a jewellers screwdriver or similar. Don't drop them on the shag pile - they're small! With these removed, you can pull out the existing wires. Replace them with your new wires, and push the IDC 's back in. You may want to check with a multimeter for connectivity.

    3. Remove the fixing clamp from around the sensor unit (it can be twisted/squeezed off) and turf it - you won't need it any more.

    4. The sensor unit is made in 2 pieces - pull it apart and you'll find a reed switch mounted on a small printed circuit board. Unsolder the wires from the PCB.

    5. Grab the moulded cable relief in one hand, the wire in the other, and pull hard. The bond between the relief and the wire will let go and you can pull the cable out.

    6. Push the new wire back into the cable relief - this is probably the fiddliest part and you may need to open the hole in the relief up with a small drill bit to get the new cable in. A bit of dishwashing detergent on the outside of the wire helps ease it through.

    7. Solder the new wires back onto the PCB, and reassemble the sensor unit (without the bracket)

    8. OK - the hard bits are now done. Fix the computer bracket to a suitable spot on the handlebars or wherever with cable ties.

    9. Route the wire down towards the speedo cable, then fix the sensor onto the wheel end with cable ties, insulating tape, heat shrink or whatever.

    10. Get the suitably powerful magnet (from Jaycar or somewhere similar - only cost a few bucks in a pack of 4 or so). Mix up some epoxy, and glue the magnet onto the disk rotor at a spot where it passes immediately below and within 5mm or so or the sensor. You may be able to use the magnet that comes with the BC800 or Cateye but I figured that the stronger magnet would ensure reliable switching of the reed switch.

    11. Attach the wire to the speedo cable and tidy up any spare - program the PC with your wheel circumference - you're done.

    PM me if you need more info!
  14. as far as i know, a speedo isn't actually necessary. i've had a car pass a roady that had its speedo disconnected, i told them that and they said it didn't matter. and there are dirt bikes out there that dont even come with a speedo to start with i'm pretty sure, the lights are all they need. but i'm not a licenced RWC tester so i'm not exactly the most reliable source i guess :LOL:
  15. As for the RWC it all depends how it is atached..

    to be more presise how the magnet is atached...

    It will NOT pass a RWC if the magnet is atached by a flimsy coat hanger wire to the rotor!! (as was the case in cosi's bike :p)
  16. My BC800 has seen 256 km/h and its peak speed reading matched that of the Garmin Etrex GPS that was on the bike at the time.

    I fitted mine mainly because of the clock. I needed a clock but the ones that Kmart, Super Cheap Autos etc. sold were butt ugly and too big. Then someone on aus.motorcycles was talking about cycle computers. I got the 800 which was about the same price as the LCD clocks that I looked at. It solved a couple of problems - that of a widly inaccurate OEM speedo, and the addition of a nifty, if basic, trip computer.

    Thing is, these days, it's more important that it's accurate around 110 km/h and lower speeds if you're concerned about speed cameras. When calibrated correctly, they're as accurate as anything out there.

    I simply snipped the wire and added a length. I dabbed a bit of silicon around the soldered joints and then slid heat shrink over that to seal the joints. Been working like that now for 3 years.
  17. The Cateyes sold over the past few years all seem to be OK to 300km/h - suspect that most brands now may use similar chipsets.
  18. I use a BC-800 with a rare earth magnet for better accuracy.

    BC make a longer cable that is designed to go on the back wheel of pushbikes. Mine cost me $13.