Here is another Extralite frame I just built for Andy K. Like Marco’s from yesterday it’s a blend of Columbus Spirit and Life with a externally butted seat tube. In almost every case when building with the thinnest of the thin tube sets I prefer to sub in an externally butted seat tube. The reason is that at the top of the seat tube there is a lot going on. You have the seat stays and top tube welded in, the slot and you have to ream and hone the tube to the proper dimension for the seat post. What I have found is that when you load all that stress into one area of a very thin tube the long term durability of the frame falls into question. Even if you do everything right over a 10 or 20 year period of time the probability of failure in that area is higher than I like. Add to that poor maintenance, rust or ham fisting a post that’s to small and the likelihood of failure goes up. Using an externally butted seat tube removes that risk and does so with only a small weight penalty.
Hi Carl,
does a frame made with extralight allow you to build a frame with different ride or durability characteristics than standard steel, or is the different mostly in the weight?
Thanks for the detailed explanation!
Maybe the pictures aren’t clear, but I don’t see an externally butted seat tube. Do you mean something like an external sleeve? I’m assuming you mean the walls are thicker at the top end, with a larger O.D. as a result?
Hi Dave, Extralite’s are built with a very limited choice of tubes. This does not allow my to do much ride tuning but if the ride of the Extralite option fits the priorities of the rider and their size it’s a great option. An Extralite frame offers good stiffness at a relatively light weight but in doing so uses very thin tubes which don’t offer the durability that a thicker tube will.
It’s not a sleeve it butting but it isn’t visible. The wall of the tube butts out from .9mm to 1.1mm so it adds a decent amount of material and you can feel it if you run you hand along it but you can’t see it. It makes a 28.6mm OD tube just under 30mm (when painted) which is why I offer my seat clamps in 30mm.