What size fork do I need?

[monkeytusmc]

I need some help as I am not sure of the answer. I am building up an old Zunow and I am need of a fork. There is a Fork for sale now with the Zunow pantograph. I asked the seller to measure the steerer shaft and the diameter. How would I know if this fork fits? Can I use a longer quill stem or adapter to make up for it if it is too small? Looking for some insight as I don’t have much experience with old school steel and quill stems.



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[Louis]

This should help:

https://www.parktool.com/blog/repair-help/fork-steering-column-length-and-sizing

Scroll down for the threaded section.

[Louis]

More from Sheldon Brown:

https://www.sheldonbrown.com/headsets.html

[jemdet]

Every fork compatibility question is asked before the quill stem comes into play. You want enough steerer length for your headtube and headset. The locknut at the top of the headset gets partially threaded, otherwise it would bottom out.

Measure your headtube, look up a particular headset's stack height, and add those two together. That's the steerer length you're looking for.

In a bind, you can omit the keyed washer from a threaded headset. It helps prevent the adjustable cup from turning when you tighten the locknut. I've typically been OK without a keyed washer, just need two wrenches and a generous amount of torque.