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Old 12-10-14, 03:59 PM
  #118  
verktyg 
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Originally Posted by armstrong101 View Post
>[COLOR=#000000]My Giro takes a 27.2mm seatpost which would indicate an SL seat tube with a 0.6mm wall thickness.

Great discussion on Formula 2 Tretubi. I'd like to contribute a thought though. I have a 1989 Quattro with Columbus Cromor stickers. I am 99.999 percent certain it has a 27.2 mm seatpost (not by me to check conveniently). The snippet I quote states a 27.2 seatpost signified an SL tubing - but given my bike, Cromor apparently also uses 27.2, so I always thought Tretubi was essentially a Cromor frame.

Please correct me if I'm wrong.
Hmmm, Just looked at a Formula 2 sticker closely. I never realized that Formula 2 was Tretubi... I always thought it some kind of mystery Columbus tubing blend. No wonder my Giro weighs a ton and rides like a truck!

The "Tretubi" stickers indicate that only the 3 main tubes are made with the designated type of tubing. The forks and rear triangle are made with some other kind of tubing - usually a lesser grade of steel (like seamed "Tubo Del Gas" Gas Pipe Tubing)!

Read sticker closely!




My 1981 Bianchi Campione Del Mondo has a Tretubi frame. The 3 mian tubes are most likely Columbus SL tubing while the forks and stays are supposed to be made of Falck tubes. It's as light as a Columbus SL frame and rides better than the other SL frames that I have... So Tretubi is not all that bad. See Cromor info below.

These are some Tretubi stickers I've seen. The first one is an early Columbus French 3 tubes sticker:




Chromor was made of Chrome Moly steel just like SL and SP but the tubing was seamed before being rolled and drawn into shape. In the drawing and butting process the seam weld became so homogeneous that it's virtually seamless. SL and SP were made from solid steel billets that were pierced and drawn over a mandrel as pictured.



Various processes for making tubing



The seat tube in Cromor tubing was 0.9mm x 0.6mm thick just like SL so it takes a 27.2mm seatpost. The down tube was 1.0mm x 0.7mm x 1.0mm like SP and the top tube was 0.9mm x 0.7mm x 0.9mm, slightly heavier than SL. Overall, Chromor was just a few grams heavier than SL, just less expensive to produce.

Here's a BF discussion about Cromor and other Columbus tubing.

http://www.bikeforums.net/classic-vi...bus-tenax.html


verktyg

Chas.
Attached Images
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ColumbusFormulaTwoPipe.jpg (5.3 KB, 834 views)
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TubeManufacturing.jpg (35.0 KB, 564 views)
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ColumbusOldDecals-3Tubes.jpg (5.5 KB, 549 views)
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ColumbusTretubi.jpg (70.5 KB, 547 views)
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ColumbusCromorTretubi.jpg (8.0 KB, 549 views)
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ColumbusTretubiAelle2.jpg (6.4 KB, 546 views)
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ColumbusAelleTretubi.jpg (6.4 KB, 832 views)
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ColumbusGaraTretubi.jpg (7.8 KB, 547 views)
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ColumbusCustomTretubi.jpg (31.4 KB, 549 views)
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Last edited by verktyg; 12-10-14 at 04:09 PM.
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