GEBE ring clearance question

Discussion in 'Rack Mounted Engines' started by ollicat, May 14, 2011.

  1. ollicat

    ollicat Member

    Well guys, I need help. I bought a used Rans Stratus and measured the upper rear fork, but forgot to measure the lower rear fork. GEBE says I need 3 3/8" clearance at 8.5" from the hub for the drive ring. I have 3 1/8" clearance on the lower rear fork.

    Does anyone have any suggestions on how I can either reduce the GEBE drive ring width or increase the clearance I have? Otherwise, I am up a creek.

    Thanks
     

  2. GearNut

    GearNut Active Member

  3. ollicat

    ollicat Member

    Dimple the frame, you mean to carve out a little notch?

    Will that affect the integrity of the fork much?

    Thanks
     
  4. Do not, repeat, DO NOT cut away any of your rear fork, nor any part of the frame. By dimple they mean to dent in the fork slightly where the ring "gear" would rub. You need a further 1/4 inch of clearance which is a lot and that big a dent could weaken the fork at the dent. I would suggest either getting a different bike with adequate clearance or you could attempt to widen the fork to clear. The idea is (more or less) to spread the fork slightly, then return the fork to parallel, but 1/4" wider. Spread the forks slightly, then bend it back parallel around a block or spacer of the correct size placed at the point where you want it wider. Heating the fork (but not excessively) with a propane torch at the points you want it to bend makes bending it much easier. Do it outdoors and with a friend standing by with a fire extinguisher. The paint will burn, so plan on repainting it. It is sort of tricksey doing it the first time. It would help to practice a few bends on an old junk bike. Gently and slowly are the way to go. Remember, you only need a very slight bend. Don't over do it, or bend it back and forth in trial and error or you will work harden and crack the metal. If you are careful and work slowly and methodically you can do it without heat.
     
  5. zean

    zean New Member

    Hi ollicat. Based on my extreemly limited experience, and I don't want to step on any bodies toes, I think that "dimpling" technique could fail at any time while riding the bike. The GEBE belt alignment has to be extreemly precise. I think you can expand both dropouts of a bicycle made out of steel with a scissors jack a little at a time then stop a while then repeat until you get 3 1/2" clearance, about an eighth of an inch more than the minimum clearance you want. Use equal numbers of washers in both sides of the rear axel to keep the deal in equilibruim. Increasing the clearance could affect the belt alignment because of the exactness required on both sides of the lower mount strap that attatches to the axel. I'm sorry, I would try a mountain bike from walmart that exceeds the measurements you described. Attatch the drive ring precisely to a strong wheel and the rest of the kit to the frame without having to bend the frame and fight the precise requirements to make the alignment correct. Thankyou.
     
  6. zean

    zean New Member

    Excuse me motorbikemike45, I didn't know that you posted ahead of me. Otherwise I wouldn't have posted. Thankyou.
     
  7. ollicat

    ollicat Member

    Thanks guys,

    I am going to try the stretch to get an extra 1/4 - 1/2 inch of clearance. I called GEBE too. The recommended it. I just have to be gentle and careful. I'll let you know how it goes
     
  8. cpuaid

    cpuaid Member

    FYI: Scissor jack was the easiest way to expand the dropouts for me also. Hopefully your stock axle has enough threads to clear the Gebe support bars for the mounting bolts. Mine was a tad too short after expansion and I had to get a longer axle.
     
  9. Wheres my dog

    Wheres my dog Banned

    SIMPLE WAY...

    I was missing by a bit on my GIANT, I took off the rear wheel and slipped on two flat washers onto the axle between the hub and the inner chain stay and then had the clearance needed!!!

    No need for a scissor jack, just two flatwashers
     
  10. Wheres my dog

    Wheres my dog Banned

    SIMPLE WAY...

    I was missing by a bit on my GIANT, I took off the rear wheel and slipped on two flat washers onto the axle between the hub and the inner chain stay and then had the clearance needed!!!

    No need for a scissor jack, just two flatwashers
     
  11. ollicat

    ollicat Member

    Washers

    Whoo Hoo! The washers did the trick. Now I have 1/8" clearance on the wheel. New problem. Now my disc brake doesn't match up. There is about 1/4" difference between the actual disc and the brake unit. Any suggestions? Is there a buffer to put the disc out further from the wheel?

    I am getting closer. . .
     
  12. Stoney

    Stoney Member

    Hey Ollicat,
    Love the enthusiasm! Nothing you won't accomplish with that :detective:
     
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