puchfinnland

I just picked up a frame,

the seat tube has the Reynolds imprint on it.

there is no question the tubing in the frame is 531, but I have heard these frames are 531SL

as the frame is chromed It is easy to look for the reynolds name on the tubing.

tips anyone?

ksisler

I believe you could use an outside caliper to measure the wall thickness at the headtube or at the seat tube. Compare whatever you can measure to the data on available tubes (check for URLs in the framebuilding resources forum)... Most of the listed tube suppliers have detailed charts on their tubes... should be something in the range 0.4mm to 0.7mm. I wouldn't assume that even if your frame has a seattube with a thickness that implies it is SL that the entire frame is SL... it is up to the builder to select the tubes he/she feels is the best mix to meet the design objectives... mixing and matching is not unheard of. But ID'ing a few tubes gives you some insight.

tuz

I have a set of SL tubes in metric diameters. If I remember right the stamps didn't specify the gauges like on regular 531. It was simply "Reynolds 531" (or "Reynolds 531 Butted" ?)

unterhausen

put it up and see if it's way to flexible

SL was just thinner. Don't think the head tube was appreciably thinner though. Not sure about the seatpost size either

Mark Kelly 

I use an ultrasonic thickness gauge for things like this. Works a treat.

ksisler

Darn -- I had just convinced a few of my long dead brain cells to revive themselves so they could tell me that there were differences in how the SL tubes were heat treated or something like that. That'll teach me to read marketing materials. So I am going back to sleep and dream about somebody trying to make a bike out of bamboo...what a hoot! zzzzzzzzzzz

unterhausen

753 was heat treated 531