From: Charles Nighbor
> > Dura Ace rear hubs had chamfers on hubs lock nuts that when you aligned
>with drop outs it spread them apart as you pulled wheel in allowing you to
>insert a wheel with a say 2 to 3 mm more width than frame spacing. So that
>is one way to solve a narrower frame spacing than the wheel spacing. Just
>buy two of them and try that. A cheap answer. I used it and it worked.
Those chamfered locknuts only came on the first-generation 8-speed hubs, but the chamfering is not necessary in practice anyway. It's no biggie to fit a 130 hub into a 126 frame, at least if it's steel.
Bruce Gordon wrote:
>The problem with squeezing oversized axles (or clamping down on undersized
>axles) into a frame is that you put a stress on both the axle and the
>dropouts. Many times this sloppy technique results in broken axles, and
>sometimes broken dropouts. The failures don't happen immediately, but they
>will happen.
When I was writing my article on this
http://sheldonbrown.com/
Fork End Alignment (Parallelism)
Spreading the frame will cause a slight change in the angles of the fork ends, so they will no longer be exactly parallel to one another (assuming they started that way.)
For higher-quality frames with forged fork ends, this can theoretically lead to problems if the fork ends aren't re-aligned. In the case of older/cheaper frames with thin, stamped dropouts, the dropouts are flexible enough that it's not a problem.
Moderate spacing changes make only small changes in the fork-end angles. For instance, spreading a 120 mm frame to 126 mm only changes the angle by half a degree. Spreading a 126 mm frame to 130 only changes the angle by one-third of a degree.
Problems attributed to misaligned fork ends include bent/broken axles. As it happens, the direction that the alignment changes when you spread the rear triangle is such that the alignment error is unlikely to cause this, because the stress it puts on the axle is opposite the stress created by the chain drive. Alignment errors in the opposite direction would be much more likely to cause problems.
Back in the days of thread-on freewheels, spreading frames commonly did result in broken axles and right-side dropouts, but it is my belief was that the axles broke because there was too much unsupported axle extending through the wide freewheels, and that most of the frame breakages occurred _after_ the axles had broken. (With a QR hub, a broken axle is not always immediately obvious, since the skewer holds the broken pieces together until you remove the wheel.)
Sheldon "Cold Set" Brown
Newtonville, Massachusetts
+---------------------------------------------------------+
| "Contrariwise," continued Tweedledee, "if it was so, |
| it might be, and if it were so, it would be; |
| but as it isn't, it ain't. That's logic!" |
| --Lewis Carroll, "Through the Looking Glass" |
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