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Barrettscv 07-29-14 03:19 PM

126mm dropouts cold set to 135, opinions?
I have a 1988 Miyata 615 touring bike. I'd like to update the bike with modern 135mm touring wheels.

The Miyata has longer 445mm chainstays and is a heavier touring frame, by 1988 standards.

There are a couple of professional frame builders in my area who could cold set the rear triangle and correctly align the frame.

The question is: will the frame survive the bending with 100% integrity?

unterhausen 07-29-14 04:03 PM

that shouldn't be a problem. I've gone further than that without issue

It was really common at one point to go from 120 to 130, and I've never seen anyone reporting an issue with that. Later bikes with heat treated tubing may well have a problem

squirtdad 07-30-14 06:01 PM

I used the sheldon brown 2x4 method to coldset a a nishiki to I don't see a problem.... assuming you are talking steel frame..... 4.5 mm per side so about 3/16 " on each side

Mark Kelly 07-30-14 07:30 PM

According to this catalogue the 1988 615 is made from triple butted CrMo tubing. They make no mention of it being heat treated so you should be fine.

Andrew R Stewart 07-30-14 07:59 PM

The most likely bad thing is that the brake bridge will break loose from a stay. But these frames were brass brazed and with that the joint strength is high and the heat affected zone is large. So I doubt that there will be an issue. The drops will need realigning after the spread. Andy.

MassiveD 07-30-14 11:13 PM

It is done a lot, and usually with a lot less care than you are proposing.

I don't really like it from a framebuilding perspective. If I had an old jig that had a 126 rear spread on it, and said no problem I can just bend the frames to 135, I don't think most builder would think that was a great way to proceed. If I did that, I could build closer to the final dimensions than spreading an old frame. So if as a group we stand for making things with greater care than this shortcut implies, why are we the place to ask about this kind of thing, and why would we hand out the advice? Leave it to the guys with the 2x4s.

Dave Kirk 07-31-14 07:54 AM

I think you'd be fine.


cycle_maven 08-01-14 09:48 AM

No problem- I believe the 615 had "mangalloy" stays, which take cold setting a lot easier than Chrome-moly.

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