29.2mm seat tube - what size front mech?

[Yog Sothoth]

Am I correct in thinking that to fit a seat tube that is 29.2mm in diameter, I need a 28.6mm front mech?

 

[cce]

no.

Is the frame meant to take a front mech? there was never a 29.2 front mech size

Have you measured the tube at the point the mech will mount?

 

[NeilM]

That's an odd sized tube.

28.6 would seem to be a closer fit than a 31.8 (which would need a shim).

 

[ishaw]

Am I correct in thinking that to fit a seat tube that is 29.2mm in diameter, I need a 28.6mm front mech?

Is the seat post the diameter mentioned, or the seat tube?

 

[Yog Sothoth]

I'll re-measure it. It's a NOS frame, unbranded, that I bought off Bankrupt Bike Parts on ebay. Nice frame, cromo, 26.2 seatpost size.No idea what brand it was as no decals.

 

[ishaw]

I'd expect there is a taper/butting on the tube and you'd need the 28.6 mech clamp. Most Cro-mo frames used the smaller diameter mech, well the ones I've had did at any rate.

 

[Yog Sothoth]

OK, It seems the tube is butted, as it's very slightly wider at the bottom than the middle. Measuring where the clamp would fit gives 29mm exactly. Could the paint add thae extra thickness? It seems to have a metallic base coat and a thick clearcoat on top.

 

[GT-Steve]

28.6 clamp mech then.

0.4mm won't upset a 28.6 mech clamp in any way.

 

[We_are_Stevo]

Tubesets wouldn't be externally butted? Ovalised maybe but...

...also depends on the material of course, alloy being thicker than steel?

Oh yeah, 'cromo' Duh!