Simple little Garmin cadence sensor hack

mikenetic
mikenetic Posts: 486
edited June 2012 in Workshop
This is very simple, and some of you may read it and go, well, "duh!" but I'm going to explain it anyway :)

I was never that pleased with the zip-tie and sticky pad fixing of the Garmin cadence sensor magnet that fits to the crank. It's an ugly looking solution.

I had a bit of a brainwave that's working out well for me. I took the spoke magnet from a long-defunct bike computer and used a Dremel to remove the thread off the back of the magnet. These things are normally rare-earth magnets, so they are exceptionally powerful for their weight.

Then all I did was let the magnet stick itself to the steel end of the pedal axle that pokes through the crank. It's removable, but the amount of force needed makes me thing it'll never drop off. Then I just repositioned the receiver to let the magnet sweep over the sensor area.

Works perfectly, and I now have totally concealed magnet attachment, and no more ugly zip ties on the crank.

Comments

  • keef66
    keef66 Posts: 13,123
    Congratulations, but you may have just reinvented the wheel. I've read this recommendation dozens of times before on here, and if I ever save up enough for a Garmin gadget I'll be doing the same.

    Save faffing with a Dremel though; you can buy rare earth magnets for pence from Ebay.

    Rich people with Ti pedal axles need not apply...
  • rolf_f
    rolf_f Posts: 16,015
    As above. Been my setup for for over a year and it wasn't a new discovery then! Neodymium magnets off Ebay. Nice and shiny and you can get ones that match the size of the pedal spindle to look extra classy.

    My setup below.

    P1100058.jpg

    These are the ones I got -
    http://www.ebay.co.uk/itm/Neodymium-Dis ... 5777637423
    Faster than a tent.......
  • mikenetic
    mikenetic Posts: 486
    I now feel like I have become a member of two special clubs. The "I figured out the magnet thing," club and the "Thread as redundant as 'What bike should I buy for £1,000''," club. :p

    Heh.
  • keef66
    keef66 Posts: 13,123
    You should still feel proud that you'd worked it out for yourself though!
  • rolf_f
    rolf_f Posts: 16,015
    keef66 wrote:
    You should still feel proud that you'd worked it out for yourself though!

    Indeed. You may have been lucky though - I don't think any of my computers have had rare earth spoke magnets. Just ordinary ones that needed an absolute minimum of clearance to work.
    Faster than a tent.......
  • Wirral_paul
    Wirral_paul Posts: 2,476
    keef66 wrote:
    Congratulations, but you may have just reinvented the wheel. I've read this recommendation dozens of times before on here, and if I ever save up enough for a Garmin gadget I'll be doing the same.

    Save faffing with a Dremel though; you can buy rare earth magnets for pence from Ebay.

    Shhhhh - dont tell him about the secret wheel magnets that involve a small rare earth magnet and a blob of araldite :wink:
  • rolf_f
    rolf_f Posts: 16,015
    Someone on here related a tale of how they decided to see if the magnet would stick to the spoke without the araldite. IRRC it lasted a mile or two before flying off and getting lost. Until he found it some days later attached to the underside of the brake calipers :lol:
    Faster than a tent.......
  • careful
    careful Posts: 720
    Ok, I will come clean and admit I must have missed this before and failed to work it out for myself (I bet there are plenty of others too). Great tip, thanks mikenetic, and Rolf F. I have ordered a set off e-bay. :D
  • Twostage
    Twostage Posts: 987
    Rolf F wrote:
    Someone on here related a tale of how they decided to see if the magnet would stick to the spoke without the araldite. IRRC it lasted a mile or two before flying off and getting lost. Until he found it some days later attached to the underside of the brake calipers :lol:
    :D
    I found out about the neodymium magnet holding itself in place on the pedal shaft when I was trying to decide where on the crank I should zip tie it. It jumped out of my fingers and stuck to the pedal shaft :) job done.
  • JamesB
    JamesB Posts: 1,184
    Great tip, thanks mikenetic, and Rolf F. I have ordered a set off e-bay.

    same here, and I`m sure extra ones can find a multitude of uses too, :)
  • nevman
    nevman Posts: 1,611
    This is spooky-not just 30 mins ago I discovered my magnet had shipped from the crank-Sram cranks are hollowed inside and the solution (bit of inner tube) had failed.Thanks for this.
    Whats the solution? Just pedal faster you baby.

    Summer B,man Team Carbon LE#222
    Winter Alan Top Cross
    All rounder Spec. Allez.
  • Twostage
    Twostage Posts: 987
    JamesB wrote:
    Great tip, thanks mikenetic, and Rolf F. I have ordered a set off e-bay.

    same here, and I`m sure extra ones can find a multitude of uses too, :)
    Not least of which is a monopole motor. Stick a magnet on the fat end of a screw, attach the pointy end to the positive end of a AA battery (magnetism will hold it), hold a bit of wire against the negative end of the battery and then gently touch the other end against the dangling magnet. Hey presto the screw will spin at 10,000 revs 8)
    Saw it on QI. There will be a video on YouTube.

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