In a message dated 3/6/02 9:34:47 AM Pacific Standard Time, velo531@hotmail.com writes:
<< However, the previous comments, I think by Bicycle Mark, about cold
setting
as a measure of brazing impact on the tubing properties is too simple >>
The cold setting comment was mine, not Mark's. I was trying to get a point
across without writing a book about it. My attempt was to illustrate the
practical effects of lower temperature brazing, ceteras paribas. I certainly
understand chain stay dents, heat treating, hardening, et. al. I've also
ridden a lot of large framed bikes with all sorts of tubing, gauges, brazing
methods and designs. In my humble experience, silver brazed frames have a
stiffer bottom bracket when you are stomping up a hill in the big chain ring,
as when attacking in a race. They should also last longer before wearing out.
I had a brand new (famous maker) Belgian frame that I could watch the gear
cables change tension on the flats while pedaling the 42 tooth ring. Uphill
in the big ring was a joke, it was all over the road. I started building
frames in the early 70s because all the Italian frames I could find were SL,
and that didn't cut it for a 62 cm frame, they were all whippy. Silver brazed
SL frames still deflect under load, but they snap back with more spring to
them than brass brazed frames. SP in the right places, transforms the
stiffness of a large frame, particularly for a strong racer. I still contend
that useful information can be derived from the alignment table, which
includes twisting the main triangle and not just the rear. The amount that
the main triangle moved on some of the frames I set indicated to me that the
joints were fully annealed.
Stevan Thomas
Alameda, CA