Leonard Bulger wrote:
> Thanks to everyone who responded. Here's what I discovered this afternoon.
>
> The mechanic mentioned that they might be 650B, which seemed odd to me.
> I had never heard of a sew-up in that size. I put an inflated Dugast
> on top of a known good sew-up and the outer diameter of the Dugast was
> about the same as the inner diameter of the other tire. Then I put the
> Dugast on a 650B clincher rim and it fit perfectly with the top of the
> base tape lined up with the bead seat of the rim. The known good tire
> hung loose on the 650B rim. The Dugasts are the wrong size!
>
> Were there actually 650B sew-ups long ago?
There have been 650c tubulars since at least 1974 when I first started riding tubulars. I suspect that's what you have. I've not heard of 650b tubulars, though that doesn't mean thay don't exist.
650C is a very popular size for triathletes and time trial bikes. The smaller wheel has slightly lower aerodynamic drag. Back in the late eighties during the triathlon craze, I stocked several 650c tubulars.
--
Peter Jon White
Peter White Cycles
24 Hall Rd.
Hillsborough, NH 03244
603 478 0900 Phone
603 478 0902 Phax
http://www.PeterWhiteCycles.com