Ottavio Dazzan by LOSA – Columbus MS

I found this beauty frame in poor conditions. The frame is made with Columbus MS tubes. This tubes were made in 90s and are very unusual. It has profil tubes. You can find many articles on net about Columbus MS tubes  and I copied this interesting article from

"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".






Here is another article about oval tubes from

Originally Posted by Reynolds View Post
Thanks all! I knew about the Gilco in Colnagos and the Caminargent - in fact my friend has one in his collection. New to me are the Daccordi and Rossin shaped tubes. The Daccordi seat lug looks similar to the Dazzan.
Was there any advantage with polygonal tubes or was it just to be different?

Altering the shape of the tube affects it rigidity. A round tube is equally rigid in all directions (assuming uniform thickness). Ideally, you want a bicycle to be stiffer laterally than vertically, as the lateral stiffness preserves the handling and transfers more power, while decreased vertical stiffness absorbs more road shock and provides a more comfortable ride. Altering the shape allows the designer to selectively increase the stiffness in specific directions, without the need to resort to increased tube thickness, which would increase weight.

Most members are aware that a larger diameter tube is stiffer than a smaller diameter tube. As the diameter increases, so does the stiffness. When you take a round tube and deform it into an oval, it is has a minor and major axis. The major axis is longer than the diameter of the previously round tube and it will be stiffer than the previous round tube, in that direction. The minor axis will be shorter than the old diameter and the oval tube will be less stiff than the round tube in that direction.

Oval tubes, as used on time trial and triathlon bicycles are more stiff vertically than laterally. This is the reverse the ideal situation, but in this case we are looking to make the tubes narrower for the purpose of reduced aerodynamic drag and the relatively steady power output of this type of event will not have as much effect of the lateral rigidity.

In the very late 1980s it became popular to ovalize the bottom bracket ends of the seat and down tubes on ATBs. The major axes were oriented laterally to increase lateral stiffness of the bottom bracket. It was even seen on some road frames, such as the Bianchi Superest II models.

When tubes are polygonal, they will still have a major and minor axes. Basically, they will be stiffer in the directions across the apexes and less stiff in the direction across the flats. Assuming that they were all cold formed from a tube of the same diameter, for any regular polygon (i.e. equal length sides and angles) the differential between the major and minor axes will become less as the number of sides increase. Basically, a octagon would would be less stiff than a hexagon across it apexes but stiffer across the flats, assuming they were both formed from a tube of the same diameter and thickness.

A longitudinal indentation along a tube works like a u-shaped stiffening channel applied to piece of sheet metal, such as a car hood. Indentations along the side of a tube will increase lateral stiffness.

By altering and orientating the shape of a tube, a designer can tailor the stiffness of a frame to more closely approach his vision of an ideal frame. Basically, it increases the flexibility of steel tube design and when used in conjunction with tubes of varying wall thickness and diameter, approaches the design flexibility of carbon fibre monocoques."

I restored the frame, but the chrome is still original. 

























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