At 1:06 PM -0500 7/3/09, Eric Burns wrote:
>Brian Van Baush wrote:
>>I'd like to caution against modifying old parts to fit your old bike frame.
>>If you machine a seatpost, brakes, stems, etc your removing material and
>>possibly putting yourself in an unsafe postion if the part fails in use. The
>>same caution applies to any frame with a dimple at the down tube, a sign of
>>the frame being in an accident.
>>Just my two cents, have a safe weekend.
>>Brian Anacortes, WA USA
>I posted about turning down a 25.4mm post to 24.5mm.
>.9mm equals .036 or .018 per side, a difference that could be
>handled with sandpaper if one was patient enough.
0.45 mm does not sound like a lot, but it can represent a significant chunk of metal. If you tried to remove that with sandpaper, you'd spend a good while. And if your seatpost walls are only 1.5 mm thick, you are removing roughly 1/3 of the material!
I have turned down seatpins, but those were 450 mm long mtb seatpins, and I cut them down to about 1/3 their length... which means that the stresses on them were much lower. I still left them a bit thicker than the wall thickness of original 1950s seatpins I was copying, just in case the 1950s material was of a higher strength.
Campagnolo used to offer different seatposts with different wall thicknesses. I don't know if the material is the same, but if it is, then turning down the seatpost should be fine.
Question: What kind of frame accepts a 24.5 mm seatpost?
140 Lakeside Ave #C
Seattle WA 98122