Ihmemies

Hello,

I have an old French bicycle frame with dropouts cut from piece of steel. They are 4mm thick.

I got new 130mm OLD Shimano 105 hubs, and I read the manual. The manual says dropout thickness must be 5mm, for ultegra and dura-ace hubs 6mm, minimum.

How critical this is? Do I really need to find a new frame with thicker dropouts? My Nishiki has for example forged Shimano dropouts which are 7mm thick, nearly the double.

The Peugeot frame has 4+4,5mm on right side with the deraileur hanger, but I don't think that counts. The fork has only 4mm too, altough front hub's manual didn't specify any thickness.

Thanks!

Charles Wahl

I'm going to guess that the minimum dropout thickness requirement has to do with how much the (standard) axle length extends beyond the locknuts when adjusted. In that respect, if you had too much axle protruding, then the QR would bottom out on the axle before it does on the dropout = BAD. You can reduce axle overhang by a) shortening the axle a little (St Sheldon says that even "none" is OK) or b) adding washer(s) between the cone and locknuts (effectively increasing the over-locknut dimension, and shortening axle overhang).

I doubt that the structural integrity, per se, of a dropout based on its thickness is in question -- forged 7 mm dropouts with adjuster screws are notoriously weak. Plus, your vintage French dropouts are not weak like "crappy bike boom" stamped ones. The only other thing I can think of is that somehow the limits of adjustment of the rear derailleur require a dropout of a certain min. thickness; but if that's the case, then your having a bolt-on hanger increases the thickness there.

Wiser heads may opine differently.

Bill Kapaun

Typical Shimano QR axles are 11mm longer than the hub spacing.
You need more than 5mm to clamp firmly.
The "nuts" are probably recessed a bit which may take up the extra length.

Ihmemies

Good find. Nuts are recessed perhaps 2,5mm. Quick release side maybe 3,5mm. Front axle is flush with dropouts. Rear axle on left side protrudes by 1,3mm.
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So in rear left is the only problem, but the axle still has over 2mm distance between the quick release nut. So maybe it has enough clearance. At least it feels like the quick release clamps tightly to dropouts and it doesn't sit on the axles.

I could still perhaps file the rear left side of the axle by ~1mm so it will be flush too. Maybe it won't be necessary though. I wish I had a more modern frame!

Ihmemies

Well it is too long if it is a problem. Is it a problem when the "nuts" are recessed inside?

The Shimano 105 hub has an axle somewhere, but the ends look like they are part of a locknut. I can't remove 1mm from it with a hacksaw, only a file would work.