Normally I lurk around in some of the other forums, but this question I want to ask you guys. I\we got some old "folders" (detatchable) bikes I want to use some more. They are the same brand (DBS) but two is 24" and two is 20".
For several reasons I want to put new forks (looks, modern brakes), and since there is at least four bikes I`d like to use what is awailable around the house, and that is alot. I know it is possible to cut the steerer tube on the frame since there is plenty but then I`we got a problem finding a long enough stem.
Is it possible to have a professional blacksmith join two tubes together to make the right lenght? Want this to be winter projects so I need to stop thinking and start acting.
The blue bike is not mine, not my photo but same type bike:
Also wanted to know if it could be done to cut the seat stays where I put some red and the seat tube where I put red (remowe a piece) and weld it back together. Important info is that the top of the seat stays is not welded to the frame. They are loose and just stay in place by the seat bolt going trough. That makes the whole thing easyer.
Wanted to do this on at least one 20" bike to give it a smaller fold. This way it would make sense to cut the front steerer tube down instead of making a longer tube on the fork. Any thoughts?
I would be hesitant to butt join any structural tubing. I too had wanted to extend a steerer tube, and though of a sleeve joint. In the end after speaking with lots of guys who know much more than me, a sleeve is no good either. Tube replacement is the proper fix. You can get steer tube most any length (single butted commonly, rifle butted sometimes). The seat stays and chain stays I dont know about, but again I'd say no to a butt joint, a sleeve joint ? I don't know. I'd be wary, I imagine there being more than one direction of force applied to the stays and seat tube. probably more so on a foldy-bike.
In sumary, you can sleeve and weld structural tubes. For instance, both Bike Friday's stems and seat stays are sleeved. You can sleeve seat posts, and it is often done to eliminate the need to ream them, and for other reasons.
The fits often need machining though, which is a problem if folks don't have the gear.
I was under the impression that sleeve joint was a no-no on the steer tubes.
I was also told, today in fact, by 3 different frame builders that cutting virgin threads on a steel steer tube wasn't possible before Josh from Ahearne Cycles did it right then and there while I looked on.