Hi All,
Id like to put couplers on a tandem that has three straight gauge ovalized tubes (38 x 31.8 x .9 wall, [34.9 dia]) . Has anyone rounded ovalized tubes in the past? I’m considering using a paragon tube block but thinking that I might need to use a custom steel block in order to get the shape more consistent and avoid springback. I’m in the process of gathering test materials now but thought I would see if someone has guidance.
Thanks!
Christian
Yep i re-round a fair bit; I ovalise/flatten top tubes ALOT and then need to bring one end back to land on the seat tube. It’s likely as simple as you think; squash em back to round.
I often just use a pair of knipex pliers, or a parrot vice, with some long strips of wood about 10-16mm thick and ~200mm long. I tape one piece of wood to either side of the tube both to act as my planar reference aswell as to stop the hard edge of the tool marking the tube, as im always after a nice gentle transition.
a soft-wood (eg, pine) tube block with rounded edges, greased, incrementally done-up, and rotated around and around the tube is an old school way of popping dents out that I’ve been pretty successful with on thin, round stuff, so maybe a rotated tube block could be put to use here aswell? I personally would be weary of the hard edge on a modern Aluminium block though.
NB, not a tandem guy. Not sure what counts as thin in the tandem world so maybe someone tandem-y can chime in there à la 34.9x0.x9 getting a heat cycle in the middle of a bunch of tubes.