"When you hear hoof beats - think horse not zebras..." In other words seek out the simplest answer or solution to a problem first!

I wouldn't mess around with a steerer with a crack in it like yours. There's an increased chance that the threaded area of the steerer could break off. There's nothing more derrière clinching than riding down the street with detached bars in your hands. Been there - done that!

The reason why the steerer cracked the way it did is that the threaded section is as much as 2" too long. Some bike makers did this to save money. They could use the same fork on a number of different size frames by just cutting the steerer off to the required length.

Ideally a stem should be inserted about 75mm to 80mm into the steerer - many stems have a minimum insertion mark. In the case of your fork the stem wedge expanded in the threaded section causing it to split!

A competent frame builder can cut off the top threaded portion of the steerer and TIG weld a new threaded section on. If well done it will be as strong as the original steerer. It wont damage the paint.

The second option is to have a frame builder replace the whole steerer. This will damage the paint and probably cost you a lot more.

Finally you could get a replacement fork but finding one with the cantilever studs and the correct steerer length, blade length and fork rake is going to be difficult.

The fork and steerer are the most highly stressed parts of a bike frame.

Forget about the shade tree mechanic suggestions unless you have good heath insurance and are VERY lucky!

BTW I used to build and repair frames and I hang out with a few local frame builders who do these repairs all the time...


verktyg

Chas.