Flying Pigeon Repair Bay Getting the Shafts

I’m not a religious man, but I often wonder if there is a devine curriculum director up there in the sky. He/she watches over us lowly bike mechanics and makes sure that we’re always working on a string of interesting new things in miniature streaks of repetition. I don’t know why, but in our repair shop one funky repair job will quickly be followed up with other repairs of the same type within days of one another.

When we first opened up it was cracked solid rear axles on low-end mountain bikes that kept rolling through our doors. I must have done a dozen of them (or more) in the first two weeks we opened up. Then we got the “Old Roadster Flood of 2009″ – guys pulling old roadsters out of the barn and bringing them in for us to tune up (mostly adjusting the out-of-tune rod brakes), swap parts, or simply gawk at.

This month stated with a fascinating repair job. I had a chance to service a Shimano Nexus 8-speed hub on a shaft driven bicycle.

A shaft-driven bicycle being worked on at Flying Pigeon LA.

A shaft-driven bicycle being worked on at Flying Pigeon LA.

The owner complained of a 2nd gear snapping out of gear under pressure, and he was right – we could reproduce the problem, and it was isolated on that gear alone. He was a big guy and said he’d ridden the wheel at a slight angle in the rear drop-out for a while until it developed this shifting problem. After opening up the hub up completely (a newer roller clutch type Shimano SG-8R31 Nexus 8-Speed Hub), it turns out that one of the three pawls inside had a return spring that was shot (pawl was stuck in the “down” position) and a small piece had chipped off from somewhere inside the hub (Ouch! How did that happen?). We ordered a new hub and swapped the new hub’s contents into the old shell (why rebuild a perfectly good wheel?).
The one fiddly bit was removing the shaft drive “cog” (or is it an “acorn”) from the hub, and then re-installing it. It is kept in place on the hub with a really burly C-clip, which is hard to both put on and to take off.

A once a year opporunity to dust up my skills and re-read all that documentation I’d downloaded months ago, cool!

But then this happened three days later:

Biomegas Copenhagen bike - an 8-speed shaft driven bike in need of a thorough check-up after being quickly assembled at Flying Pigeon LA.

Biomega's Copenhagen bike - an 8-speed shaft driven bike in need of a thorough check-up after being quickly assembled at Flying Pigeon LA.

Ack! Again with the shaft drive! No worries, this was an easy “line up the little yellow dots” job – just a little shifter cable tensioning and everything was ready to go. The secret is how you check the shift cable tension.

To adjust shift cable tension on a shaft-driven internally geared bike, simply unscrew this panel on the rear of the Biomega (or any shaft driven bike I’ve run into so far):

Those two unscrewed screws need to come out in order to remove the protective panel and adjust the Shimano Nexus 8-Speed Hub.

Those two unscrewed screws need to come out in order to remove the protective panel and adjust the Shimano Nexus 8-Speed Hub.

This cover protects the shaft drive from muck and grit, remove it to see the mechanism that changes gears on the Shimano 8-Speed Hub.

Those two yellow marks should line up when the Shimano Nexus  8-Speed Hub is properly adjusted for shift cable tension.

Those two yellow marks should line up when the Shimano Nexus 8-Speed Hub is properly adjusted for shift cable tension.

Once removed, this is how the little yellow dots should look when the Shimano Nexus 8-Speed Hub is in 4th gear.

So the Biomega Copenhagen in Silver is now all done and is waiting for it’s owner-to-be (Danish skin-care guru Ole Henriksen, we’ve been told) to arrive back in Los Angeles. Thanks to that big educator up there in the sky for delivering these two shaft drive bicycles to our repair bay!

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4 Comments

  1. Guido
    Posted January 20, 2011 at 11:51 pm | Permalink

    Are these bikes any good?

  2. Posted January 21, 2011 at 10:21 am | Permalink

    Guido,

    Good is such a relative term, it is hard to answer in a way that won’t raise the hackles of one type of bike snob or another (we include ourselves in that bike snob category).

    Biomega bicycles are a blend of high-minded design and practical needs. Like every bicycle, they represent a compromise of materials, aesthetics, physics, and available materials and material costs.

    Do I think these are junk? Far from it. I think with Biomega bicycles you are paying a premium to have a bike that says a lot about what you are interested in and what you like – “simple” design, modern aesthetics, utility over racing.

    Would I buy a shaft driven bicycle? Nah. It’s not my thing. I think the shaft drive is a novelty with few practical benefits over a traditional chain-driven drive train that is covered with a chain case. However, that is my personal preference, and not based on anything more than my worry about replacement parts and self-maintaining the thing. I will admit that taking the chain off a bicycle and replacing it with a shaft drive does some cool things to the way a bike looks.

  3. Ionel Radu
    Posted April 13, 2012 at 8:37 am | Permalink

    I have now for more than four years a Biomega Copenhagen Bike and have never a problem.I like the ride it is very light very intuitive and relaxing …
    try one and you will fell the difference

  4. jaafaru friday
    Posted July 14, 2012 at 10:26 am | Permalink

    please can you sent me the shaft drive constructional assembly details. this bike is spectaculer

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