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Re: [Geared_hub_bikes] Alfine 8spd to 130mm

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  • Rick Paulos
    Bending aluminum isn t like bending steel. You get to bend aluminium ONCE. Try to bend it back and it snaps. Even the first bend can cause cracks you can t
    Message 1 of 3 , Oct 12, 2011
      Bending aluminum isn't like bending steel.

      You get to bend aluminium ONCE. Try to bend it back and it
      snaps. Even the first bend can cause cracks you can't see.

      Respacing the rear end of a bike frame is a multi step process. I've
      done a dozen or so steel frames and only steel. It's not an option
      with carbon, and I wouldn't try it on titanium. Never needed to do an
      aluminum frame.

      Bend each stay out half of 5mm. There are different methods for that
      depending the particular bike and which direction you are going, in
      or out or left or right. There is 'spring' in all bike frames
      especially when the wheels are removed so you have to bend farther
      than 2.5 mm, more like an inch or two and let it spring back and see
      where you are. I have a park long handled frame tool and i've used
      2x4s and even steel building posts (immovable object) as an anchor
      point. You want controlled leverage, just having the chubby new guy
      jump on the frame isn't control. You can use "the string method" to
      monitor so your bends are equal.
      Next bend each dropout inward a slight amount to keep them parallel
      to each other. You want the dropouts parallel so you aren't adding a
      bending force to the axle, especially with an IGH, hollow axle hub or
      old freewheel type hubs. An axle that is trying to keep the frame
      straight will break much sooner. I have a set of Park dropout
      alignment guages/tools for that. On a AL frame, that bend is
      concentrated right where the dropouts are welded to the ends of the
      stays. Worst you can do is break that frame and then go shopping for
      one with the desired spacing.

      re-dishing is done to keep the rim centered in the wheel. You might
      need that done to compensate for adding or removing spacers on the
      hub to get it to fit a particular frame. Wheels that aren't dished to
      center will track funny when you try to center the rim between the chainstays.

      I don't know if the Alfine has lock washers between the lock nuts and
      cones, but removing those washers could gain you 2 or 3 mm.

      a stepped axle, ie, one that gets thicker. on IGHs, thats usually
      right where the axle fits in the dropout. The old shimano 3.3.3 hubs
      were like that to accommodate the antirotational washer. You can flat
      file out the dropout slot easy enough as needed. Do an equal amount
      top & bottom to keep the wheel aligned correctly.

      I seen plenty of bikes where the wheel spacing doesn't match the
      frame spacing. It's just a bit harder to change out the
      wheels. Trying to wrestle a wider wheel in to a
      narrower frame is more difficult. 5mm isn't that much to wrestle with.

      rick


      At 02:44 PM 10/12/2011, you wrote:
      >I recently purchased an Electra Townie 3spd (aluminum frame)
      >thinking that I could use my Alfine 8spd hub to upgrade the bike. I
      >built up a new rear wheel but when I went to install it, I found
      >that the new hub was 135mm and the frame was 130mm. I took the wheel
      >to my LBS to see if it could be re-dished. I was told that the axle
      >is stepped and it would have to be machined to make it work. The LBS
      >said I could "probably" get away with cold spreading the frame. Can
      >anybody help me out here?
      >
      >
      >
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