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Thread: RotoR Apart

  1. #1
    Dr Gadget is IN
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    RotoR Apart

    I realized that one of the drag link dust covers on my RotoR crank had gone away, and some other maintaining was needed - so I took 'er apart. Left the BB in the shell, just took out the axle assembly, which exposes all but the spider bearing. I could take the spider off easily at this point, just push it off the eccentric of the BB - but its smooth as butter and no need.

    Pic1: Here is the spider on its eccentric mount. The marks are for getting the eccentric clocked properly, but require the crank to be assembled. Note the two large posts that actually drive the spider.

    Pic2: The axle assembly. The right crank arm (the one you see) rides on a bearing on the end of the axle - the removed left arm drives that other link behind the axle.

    Pic3: The other side. That big tab is basically the end of the left crank.

    Pic4: Here it is stuck back together - the left crank link is not on its drive pin, but the right is.

    Clear as mud? As the spider moves around its eccentric mount, the links get different leverage on it. This is what speeds up/slows down the crank arms. Clocking the eccentric in the BB shell lets you line up the crank pulses with the power pulses of your legs. Get it right and it feels so smooooooth. You can see the 5 hash marks on the spider in Pic1 - that's the range of adjusment. The difference between one mark and the next is noticeable. Going to the longer marks gave more leverage, but made things "lumpy". And on my fixedgear drivetrain, it also took away from my resistance levearage. Going to the shorter marks improved resistance at the expense of power - and also got "lumpy". Just a little above the mid mark/arrow is perfect for me.
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  2. #2
    mtbr member
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    Mmmmmm Rotor cranks. So tasty....unfortunately so expen$ive.

  3. #3
    Geritol Power
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    Expensive indeed!

    Just over $800 for the regular MTB cranks

    Hey Wade, thank you for the pictures. I never knew about these until I noticed your signature last night. I looked them up and there's a distributor right here in San Diego.

    I'm very curious about these cranks because my knees are really hurting these days and I don't want to go under the knife. Damn doctor needs a new car or something

    I was actually thinking about the old school Shimono Bio-Pace stuff on my road bike from the 80's and thinking something like that might help.

    Are they worth it?

    Thanks for sharing, Chris

    EDIT: I did a little more searching and found some answers but I'd still like to hear more.
    Last edited by Duzitall; 01-27-2008 at 09:29 AM.

  4. #4
    Dr Gadget is IN
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    Your Mileage May Vary.

    RotoRs do exactly what they are advertised to do. They wipe out the dead spot in your stroke, and they improve your leverage. In my fixed gear application I could tell that the power balance of power vs resistance (back pedalling) changed as I adjusted the orientation.

    The first Q? is: Is what they do worth $800? Well, I didn't think so - so I scored a pair on closeout from rotorusa for $300, and I've definitely had my fun with them and continue to do so. Last time I looked they had a few deals, but none right now.

    Q2? is: Will they help with knee pain? Not a clue. They do feel much smoother than regular cranks (when adjusted well). If you're running SS or Fixt they will help your knees - IMHO.

    You could try their Q-rings. Adjustable elliptical rings.
    Fatbikes are much more fun than they should be allowed to be!

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  5. #5
    Geritol Power
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    Thanks again Wade

    Quote Originally Posted by wadester
    If you're running SS or Fixt they will help your knees - IMHO.

    You could try their Q-rings. Adjustable elliptical rings.
    No SS or fixie at the moment but I live in the hills. It's the long climbs ( I like em ) that get to my knees. I'm sure it's a combination of things like age, heavy bikes, too much work and not enough play, old injuries and such.

    I'll call the local dist. here is San Diego and see what he's got available, rings or discounted cranks perhaps.

    Chris

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