Framebuilders - Olumbus SP and SL NOS

Can anyone describe the nature and differences between Columbus SL, and Columbus SP? I did a search and found:

Columbus SL tubing was .9mm x .6mm x .9mm for all main tubes

I also found it described as too light for heavier stronger riders (which is odd given that those dimensions are pretty standard for heavier duty bikes.

Apparently the sets I am choosing from only have 1" top tubes which could be part of the problem (thinking touring bikes for larger riders mostly).


All I could find about the SP is that it had heavier downtubes.

The SL comes in A, B, C, lengths, presumably butt lengths, does anyone know the sizing on those.

I was also wondering whether this stuff can be tigged. I'm currently buying it for lugs, but I wouldn't want to have too much of anything around that didn't work for TIG also. I'm thinking out of the box here. Magnesium can be tigged. Just because a manufacturer was slagging tig, doesn't mean it won't work. Was this stuff HTd?

My 62cm '87 Paramount is built with a mix of SL and SP. SLX was used on 56cm frames and smaller, while the SL/SP mix was used on larger frames like mine. I don't know whether or not it's heat treated, but I do know this was before Schwinn began using OS and the judicious use of the heavier walled SP mixed with the lighter SL made the larger frames stiff enough for big (and heavy) riders.

As you say, SL was 0.9/0.6/0.9, while SP was 1.0/0.7/1.0.

http://i32.photobucket.com/albums/d7/k4drd/Bicycles/SLX-SL-SP.jpg

Thanks Stan, that helps a lot. I think these tubes are a particularly good deal, because they come with a free Bolex watch with every box of tubes!!

SP is heavy duty stuff. It's small diameter so it shouldn't ride like a truck, particularly for touring duty. Should hold up will to denting also unlike most of the newer thin-wall tubesets.

Enjoy.

What are the ABC butts. Also, what do you think is the effect in having a 1" top tube, versus a 1,125". Obviously it is a lot less stiff, but does it mater? Is this the kind of thing that would affect a mostly road bike. I'm working on a classic retro style, and I'm sure I have owned such bikes before but I never bothered to note the tubes in them. It may not happen, it is really looking like it might be tough to get the angles I need with lugs. I can do a 69er, but I'm not sure that will fly!

Both the top tube and the down tube are smaller diameter compared to OS tubesets, and in my experience the down tube has a greater influence in terms of stiffness. At any rate, SP is thick enough so the frame should be reasonably stiff regardless of the small diameters, even for a large rider.

I read that the TT and seat stays are the least solicited tubes in a frame. All of my bikes (mid-80s to mid-90s) have 1" TTs, in sizes 54-56cm.