gugie 

If the brazing at the bridges breaks when spreading a rear triangle, it was a crappy braze job. I've had a couple of frames brought to me with this issue, it was clear that most of the "braze" was in actuality just dried/consumed flux. A properly brazed bridge will hold together even if you bent the stays at a 90 degree angle.

I typically charge a six-pack or equivalent in hard liquor, but I'm not that reputable.

gugie 

Further comment on spreading a rear triangle: IF the drive side has an indentation for chainring clearance (fairly common on vintage frames), it will yield (permanently bend) long before the non-drive side. If you try to bend them both at the same time, the dropouts won't be centered.

Even if they're not symmetrically indented, I always bend one side at a time, figuring there's always one side that's a bit stiffer than the other.

1. Check spacing
2. Check centering
3. Bend one side
4. Rinse and repeat until you've got the spacing you want and the dropouts are centered.
5. Make dropouts parallel, check everything again.

Nemosengineer 

This was the final push to get a Raleigh Pro to 130mm, 531 is really springy stuff, the spreading tool is 10 inches of 3/8" X 16 grade 8 all-thread with two standard washers and two fender washers to spread the pushing forces evenly across the dropouts, there are 16 washers total on the tool. the outer nuts are are just there to follow the push and are never more than finger tight.



It took quite a few passes to spread the frame, once the frame started to take a set I was only turning each nut 1 full turn at a time, removing the tool measuring the drop-outs and repeating until I got to my desired spacing of 130mm.
Before and after the cold setting the drop-outs were aligned, the symmetry was verified to be on the money, Tools used were the Park drop-out alignment and Park frame alignment tools.



: Mike

Camilo

Yes - this is exactly what I ended up having to do to spread my mid-80s steel frame. And you really have to over extend the frame to make it bend a little. Takes a little time and cautious application of strong pulling on the frame to get used to the force and amount of spreading you have to do. I couldn't do it with a threaded rod, but put the BB in a vice and just pulled on the frame by hand, measuring the spacing and alignment as I went along.

It's pretty easy to make a simple tool to square up (parallel up?) the dropouts with a couple of long threaded bolts and nuts.

In vice to spread by hand

Checking rear spacing

Checking frame alignment

Parts needed to check drop out alignment

Attached to dropouts to check dropout alignment

Dropouts not aligned

Dropouts aligned

DiegoFrogs

This has the 531 rapid taper chainstays, correct? If so, it seems plausible that you could get symmetrical results with a single threaded rod adjustment. I have a bike like this, and use it in the original 120 mm spacing. I love the ride, and really love how elegant the treatment is.

If you try the same with unevenly-crimped stays, all bets are off.

Nemosengineer 

I recently completed a cold set of a S/R Triathlon frame from 120mm to 130mm, these are the tools that were used.







These are the results.








Dead straight and ready to build.
: Mike

scarlson 

My Ron Cooper was spread from 126 to 130, toured on it for six months, then spread it again to 135. When we did this, we put clamps on the brake bridge and put an automobile scissor-jack between the dropouts. This worked great. But right at the maximum extension, the clamp on the brake bridge fell off! We were horrified, but that brake bridge still exists to this day. I'm thinking about de-brazing it and moving it to improve the fenderline sometime once my Trek is completed.

I've spread Vitus 979 frames from 126 to 130, not once but twice! From 126 to 130, so only 2mm each side, but as a rule I don't use mechanical tools on these frames because I want the feedback in my hands, to feel the metal so I can be delicate with them. They're pretty hard to do. I did mine, vowed I'd never do another, and then my friend wanted his done! Mostly I really hate the stress and anxiety it causes me to do something that isn't recommended by established canon. But usually what I find on these is people just spring the frame apart to stuff in a modern hub, which is likely worse that what I've done. So far they haven't broken (and I don't think they ever will).