Mark M. Koepke wrote:
> Hi, I have Raleigh Team Pro that I'm restoring. It's a SB bike and
> made of 531SL. I had a SR gruppo ready to install right down to
> two Campy SR posts top chose from in 27.2 and 27,4. The frame,
> however, needs a 26.8!
I'm wondering why a 531 SL frame would take a 26.8 seat post. I see seven possibilities:
1. Metric-sized tubes (28.0 mm Outside Diameter seat tube versus English, 1-1/8" = 28.6 mm)
2. Single-butted seat tube in upside down with the butt at the top (a major screw-up!)
3. Double-Butted tube (they used a down tube for the seat tube)
4. Single-butted seat tube but not really 531 SL (heavier gauge)
5. Plain-gauge tube, not butted at all.
6. Real 531 SL single-butt seat tube put in right, but with an internal sleeve brazed in the top to reduce the ID like on old Cinellis (not likely, the sleeve would have to be too thin in this case)
7. Distortion and/or pinch bolt ears bent in, making it seem to take a smaller size than it really should.
I'm only moderately curious, and some of those possibilities would be very difficult to check for without cutting the frame up, so we'll probably never know. Exception would be the metric tube possibility, easy, just measure the OD. Sometimes by pushing a rag down the tube with light oil or solvent, you can make the inside of the tube 'glisten'. Then with a light shining up the BB end, you can look in the top and see the butt transitions. They're subtle though, and many things can get in the way of this working.
If it's distortion, it might be best to try to fix it, though this should be done by a framebuilder or a very experienced mechanic. Heavy-handed reaming can ruin it. If the ears are bent in, bending them back out can be done, but must be done very carefully to avoid further damage.
How much does the bare frame weigh and what size is it? This could give an indication of whether they substituted heavier tubes.
Mark Bulgier
Seattle, WA USA