The 411 in the Columbus MS Tubeset
The MS set is the most unusual tube set I’ve ever seen and represents the beginning of when Columbus really started investigating how bicycle frames are stressed…or got bored pumping out the same old EL/OS tube sets everyday…or started smoking crack or…
Anyway, each of the MS tubes has a different shape. The non-drive side chainstay is triangular shaped and a larger flat-sided oval chainstay was used on the drive-side. The top tube is lemon shaped (not ovalized, it has distinct ridges down the sides of the tubes) with the long axis traversing the head tube. The down tube has tear drop shaped but designed to be mounted upside down (pointed edge facing the ground) relative to normal orientation of a tube this shaped. The seat tube is a long taper from 28.6mm at the BB shell to 26.4mm at the top tube end and designed to take a 25.4mm seat post.
The MS lugs are equally unusual, first in that they’re shaped to accept the tubes of course, but also by the lug points and the BB shell in which the seat tube is oriented to tangent to the FRONT of the shell and the down tube which is oriented with the top end of the tube meeting the center of the BB shell, meaning the leading edge of the down tube is well off the tangent of the bottom of the BB shell. This makes the bottom of the BB shell look very much like the flat bottom of a rowboat.
Columbus had to be fairly daring to produce this set of tubes. Besides the dedicated tubing dies, they faced the high cost of the lug development and production as well since lugs were the preferred construction method of the day. They could have just released the tubes for use in fillet-brazed construction, but Columbus’ designed orientation of the tubes at the BB shell wouldn’t allow that method either. It is a surprisingly light tube and lug set being under 4 pounds with uncut full-length tubes and lugs, dropouts, and normal brazeons. For a bike world dominated by round tubes, it was an anomaly and looking back, ahead of its time. Didn’t matter though, it didn’t last long. My understanding was that it was actually designed in the late 70’s or early 80’s, but not released until ’86/87. It died quickly and it’s very rare to see a MS tubed frame today.