Bicycle Mechanics - 31.8 mm seat tube and 32 mm claim on front derailleur

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vinnydelnegro
08-07-06, 02:53 AM
Hi folks. I have a frame that has a 31.8 seat tube (this is the outside diameter) and a campy daytona front derailleur that is 32 mm. I haven't put the derailleur on yet, but I was wondering if this would work. Seems like 0.2 mm wouldn't make much difference, but I don't want to assume. As always, thanks for the advise!

cs1
08-07-06, 03:18 AM
They are considered the same thing. Good luck

Tim
vinnydelnegro
08-07-06, 10:28 AM
They are considered the same thing. Good luck

Tim

Thanks Tim...that is great news!

moxfyre
08-07-06, 11:00 AM
Hi folks. I have a frame that has a 31.8 seat tube (this is the outside diameter) and a campy daytona front derailleur that is 32 mm. I haven't put the derailleur on yet, but I was wondering if this would work. Seems like 0.2 mm wouldn't make much difference, but I don't want to assume. As always, thanks for the advise!
I think they are the same thing... but if there really is a difference and the derailer is slightly too loose, use a very thin shim. A bit of electrical tape around the seat tube should be enough to fill the gap :) I've done it before and it works great, allows you to get a tight-fitting front derailer without crushing the paint of the seat tube.
vinnydelnegro
08-07-06, 11:23 AM
I think they are the same thing... but if there really is a difference and the derailer is slightly too loose, use a very thin shim. A bit of electrical tape around the seat tube should be enough to fill the gap :) I've done it before and it works great, allows you to get a tight-fitting front derailer without crushing the paint of the seat tube.

hmm...not a bad idea with the electrical tape. i think i'll give that a try just so i don't chip the paint. it doesn't cause the derailleur to slide?
moxfyre
08-07-06, 11:27 AM
hmm...not a bad idea with the electrical tape. i think i'll give that a try just so i don't chip the paint. it doesn't cause the derailleur to slide?
Nope! Because the electrical tape has a bit of give to it, the derailer clamp bites into the tape and holds very securely. I've added electrical tape to most bikes that I've built or repaired, and never had a derailer slide.
HillRider
08-07-06, 02:46 PM
Derailleur sizes are often rounded off in the manufacturer's literature. Seat tubes are 1-1/8" ( 28.57 mm, often given as 28.6 or even just 28mm), 1-1/4" (31.75 mm rounded to 32 mm) and 1-3/8" (34.92 mm or 35 mm).
redtires
08-07-06, 03:03 PM
If you think about it, 1mm is about the thickness of a dime. So what your dealing with it 2/10ths of the thickness of a dime. Would you worry about this too much? Neither would I.
HillRider
08-07-06, 07:19 PM
If you think about it, 1mm is about the thickness of a dime. So what your dealing with it 2/10ths of the thickness of a dime. Would you worry about this too much? Neither would I.
I'd worry about it when sizing handlebar-to-stem fit and seatpost-to-seat tube fit but not front derailleur clamps.