Cold setting vintage steel frames

I want to quickly highlight some of my exploits in cold setting vintage steel frames. This can be essential skill when resto-modding vintage steel mountain bikes. Adjusting the rear drop-out width from either 126mm or 130mm to a more standard 135mm spacing will allow you to fit an 8 speed HG freehub, which in turn can accommodate an 8, 9, 10 (and sometimes 12 - i.e. SRAM NX) speed cassette for 1x conversions.

This was something I had always heard about, but always felt it to be a risky endeavor. I wasn't sure how you "measure" your effort to avoid bending your chainstays too far, and didn't really know how to ensure the right and left side would bend equally (to maintain frame alignment). 

As with most things, there are numerous Youtube videos, blog posts, etc. about the topic and I would be remise if I didn't link to Sheldon Brown's method.

However, it is my opinion that Youtube's RJ the Bike Guy outlines the best method for cold setting here. 

Using a threaded steel rod, RJ's method allows you to incrementally expand the width of both the left and right chainstays in unison. This allows you to measure your effort, while maintaining good frame alignment. 

Cold setting the rear triangle using RJ the Bike Guy's method

To cold set the rear triangle from 130 to 135mm, I had to expand the rear triangle out to 160mm. 

As RJ outlines in his tutorial, once complete its worth checking your dropout alignment using his home made tools. These DIY dropout alignment tools are covered here.

Check and adjust the alignment of your dropouts after cold setting

Its also always valuable to double-check overall frame alignment once complete. For that, I would still recommend Sheldon's method of using the 'string method'. 

  1. Tie a piece of string to one rear forkend so that the string runs along the outside of the forkend.
  2. Run the string around the front of the head tube and back to the other rear forkend, as in the photo (below). 
  3. Pull the string taut, making sure that it's contacting the same part of each forkend
  4. Use a ruler to measure the distance from the string to the side of the seat tube where they cross. Take this measurement on both sides. It should be the same on each side.


 God bless RJ the bike guy! 

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