Kaisei Tubing

Posted by: Jan Heine Category: Framebuilding supplies

Kaisei Tubing

It’s no secret that we love steel bikes. Steel allows us to build the bikes we need for our adventures – bikes where every detail is optimized to the nth degree. You can imagine our concern when True Temper, one of the most important suppliers of steel tubing, decided to leave the bicycle market. Without steel tubes, especially the superlight ones that True Temper was specializing in, there wouldn’t be any more of the bikes we love.

What to do? We thought about who made the best steel tubing in the world today. There is no simple answer, but Kaisei in Japan was an obvious candidate. Kaisei is unique in that most of their tubes are used for professional racing bikes: More than 2000 Japanese Keirin riders race on steel bikes, and most are made from Kaisei tubing, which is known for its high quality.

Kaisei is an interesting company, because they are just a manufacturer, without any marketing. All they do is supply tubes to Japanese framebuilders. And since those builders work for professional racers, there is no need for fancy names and stickers. As a result, Kaisei uses Cromoly tubing. It’s the strongest and most reliable, and the thinwall tubes are heat-treated. I like that no-nonsense approach.

Kaisei tubes are rounder than most, and their walls are more uniform in their thickness. They match their spec exactly, unlike some other tubes we’ve measured. The heat treatment is uniform, and it’s designed to strengthen the tubes without making them brittle. This precision reduces the risk that a frame breaks due to defects in the tubing. For Keirin racers, this point is very important: They are not allowed to change bikes during a weekend of racing, and if their bike breaks, they are out of the races. And since they live off their prize money, this means they have no income, either.

In the past, Kaisei tubing was designed for smaller frames, since Japanese (racers and otherwise) tend to be shorter than the average westerners. The thinwall “bellies” of the tubes were relatively short, which meant that tall frames were heavier and stiffer than necessary. In addition to offering these “short” tubes, we worked with Kaisei to make “long” tubes with longer thinwall “bellies” that are optimized for taller frames. Since we commissioned the tooling for these tubes, they are available exclusively from Compass Cycles.

To complement the excellent Kaisei tubes, we developed a selection of framebuilding parts. They are made by Longshen in Taiwan to the highest specifications. The new Compass fork crown is a perfect fit for the Kaisei TOEI Special fork blades that we use on all our bikes. The new fork crown combines classic looks with a modern box section construction. The result is an ultralight and super strong fork crown.

The Compass bottom bracket shell is specifically designed for wide tires. The chainstay sockets angle outward a bit more (10°) to accommodate curved chainstays. This provides extra tire clearance. It’s the secret for using wide tires with road cranks. Designed for standard-diameter tubes and with enough material to carve and match your preferred lug shape, the Compass bottom bracket shell combines light weight with versatility.
These are just a few elements of our new frame tubing program. Instead of lamenting the demise of a major supplier of steel frame tubing, we worked on a replacement that is arguably even better. Now it’s easier than ever before to have your dream bike made!
Click here for detailed specs of the tubes, as well as our complete program of braze-ons and other framebuilding parts.
Photo credit: Paul Keller (Photo 4).

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