Rear axle damage with with shift kit?

Discussion in 'Performance Mods' started by a/c man, Jan 11, 2010.

  1. a/c man

    a/c man Member

    Has anyone else bent or broken your rear axle with the SBP shift kit?
    I know I'm not as gentle as I should be, but so far I've bent one standard axle, and snapped one QR (quick release) rear axle in the last 300 miles or so.
    Just got my new cromoly axle in the mail the other day. Lets see how this one holds up. I don't like high speed death wobble.

  2. give me vtec

    give me vtec Active Member

    nuvinci hub... that's all I need to say.
  3. Pablo

    Pablo Motored Bikes Sponsor

    I happens. That's why we write:

    On our Requirements Page

    Quick releases will work if they are HD. I'm two years plus into my QR and it's still perfect, and I slam shift.
  4. a/c man

    a/c man Member

    I don't know if the quick release axle was heavy duty or not, it seemed to be cromoly.
    I do know that the skewer stayed intact long enough for me to limp my bike home.
    I try not to shift hard but the fact is that shifting gears is so much fun sometimes I can't help but to get carried away. Anyone out there who is still riding without one is missing out on a pi$$ pot of fun.
  5. Fabian

    Fabian Well-Known Member

    Hi Paul

    I think part of the problem is variation in quality of materials used on different mountain bikes.

    So far i've travelled 2900 kilometers (1812 miles) on my bike, equipped with basic Quando hubs.
    I am very surprised at how well the standard rear wheel assembly has lasted - was expecting the free-hub and ratchet pawls to get blown to pieces from the torque of the SickBikeParts Shift Kit.
    The rear hub has given perfect reliability, even with the extra weight my loaded trailer places on the drive train.

    Shock loading could also be another factor, where the rider shuts off the throttle and slams it back open again allowing a sudden rise in engine revs before the slack in the drive system is taken up with a harsh transfer of torque.
    Somewhere along the line, the weakest link is going to take the most punishment and if low grade materials are used, mechanical failure is to be expected.

    Last edited: Jan 13, 2010
  6. Hawaii_Ed

    Hawaii_Ed Member

    No issues on mine, I have quality rims though, I also shift hard!
  7. Nitropeewee

    Nitropeewee Member

    Ive got mine on a shimono inter 7 (not sure what the axle is made of) no problems fer me. Im also pretty hard on it, pull a trailer with 110 mig welder n all my gear about 100 er so extra lbs. Only thing ive had trouble with are the sprockets on the jack shaft come loose after a hard ride. N yes i used locktite. think mabey i didnt get the shaft square with the mounting plates.
  8. Pablo

    Pablo Motored Bikes Sponsor

    Nitro - did you file flats on the shaft? That's the best trick, IMHO.
  9. Nitropeewee

    Nitropeewee Member

    Yeah did that too. Mabey just not enough. Havent really messed with it too much here lately, weve been gettin snow bout every other day here in se ohio. Spring is right around the corner though.
  10. james65

    james65 Member

    Broken axels

    I have not had the problem but would like to know where are they braking. I am wondering wher they brake? middle, center, clusterside?
  11. Fabian

    Fabian Well-Known Member

    I've heard something about axles breaking but i've never even had the slightest hint of a problem and my bike uses low specification Quando hubs and axles.

    On top of that, my shift kit is set up with a super low first gear for pulling massive loads or climbing seriously steep hills.

    Many times i've thought to myself: this level of torque should snap axles or snap chains on a regular basis, or even break the welds on the bicycle frame.

    The fact of the matter is that the opposite is true.
    I've travelled over 5000 Kilometers (3000 miles) and i've never broken an axle.
    I've only snapped one chain because i previously damaged the links with early chain suck problems.
    The chain ran for 1000 kilometers (600 miles) with damaged links before breaking in half.

  12. abikerider

    abikerider Member

    I've heard that if the dropouts (the part of the frame the axle fits into) are not parallel to each other that it can cause this sort of problem by putting stress on the axle just by tightening the axle nuts or quick release. Also, hubs with freewheels are more prone to bend axles than hubs with cassettes. With a cassette hub the bearings on the right are closer to the frame and put less stress on the axle while going over bumps. You may want to eyeball your rear dropouts to see how square they are. If you replace the wheel, you should get a cassette style hub to replace it. Hope this helps.