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
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.
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?
>Yahoo! Groups Links