torqueless
Senior Retro Guru
Re:
I just put a metal rod down inside the seat tube until it met the obstruction of the end of the BB lug, and marked the rod level with the top of the seat lug. Then I withdrew the metal rod, put it up the outside of the seat tube with one end level with the outside join between the BB lug and the seat tube, and marked the rod again at the top of the seat lug. The difference between the two measurements was 25mm (approx!)
A derailleur will leave you with catenaries. So will a single speed in horizontal dropouts with the wheel pulled back against the chain tension. If you ask me, that will leave you with an ideal chain tension, funnily enough. Vertical dropouts are unique in the mischief they can cause in this respect... unless you have access to chainwheels/sprockets in one-tooth increments to find a 'magic gear', and are prepared to change them when your chain stretches and renders your 'magic gear' not quite so magic..
Well, the great thing about a seat tube is that you can find out.. more or less. As luck would have it, even Torqueless has an old front-ended '80s (aluminium) Vitus frame knocking around- too good to dump, too damaged to ride.
I just put a metal rod down inside the seat tube until it met the obstruction of the end of the BB lug, and marked the rod level with the top of the seat lug. Then I withdrew the metal rod, put it up the outside of the seat tube with one end level with the outside join between the BB lug and the seat tube, and marked the rod again at the top of the seat lug. The difference between the two measurements was 25mm (approx!)
A derailleur will leave you with catenaries. So will a single speed in horizontal dropouts with the wheel pulled back against the chain tension. If you ask me, that will leave you with an ideal chain tension, funnily enough. Vertical dropouts are unique in the mischief they can cause in this respect... unless you have access to chainwheels/sprockets in one-tooth increments to find a 'magic gear', and are prepared to change them when your chain stretches and renders your 'magic gear' not quite so magic..
