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a tube is not a tube is not a tube

Got some new tubes in from Reynolds this week that I like.

a tube, a tube, a tube

Over the years I’ve developed a feel for what tubing diameters and wall thicknesses work for riders doing what they do. A lot of my frames have a 35mm downtube, 28.6 seattube (for a 27.2 post) and a 31.8 toptube. I like the way frames like this ride. I like the stiffness you get from a big downtube. It’s alway a compromise between stiffness and comfort but this is what I like at the moment. And I’m the boss.

Anyway, the one problem with those tube diameters is that the toptube to seattube join is problematic because you need to join a tube with a bigger diameter (31.8 toptube) to a tube with a smaller diameter (28.6 seattube). In order to miter the tube to get a good fit you need to ovalise the top tube so that it’s taller than it was, but the sides of the oval are now less than the 28.6 of the seattube. This is a pain in the arse to do and it’s not a task I’m fond of.

a tube, a tube, a tube

So, the good news is that I now have some custom drawn Reynolds 853 butted top tubes that are tapered from 31.8 at the headtube (front) end, down to 28.6 at the seattube end. This makes life much easier and building that part of the frame less stressful.

If you’re interested in how these tubes are drawn there’s a nice wee blurb here: Reynolds Butted Tubes

posted by steven - September 30th, 2011