Stack height question

[ishaw]

I'm looking for some forks for a small frame. I'm not sure which headset or stem I'm going to use on the build yet, and this may be dictated a bit by the forks I may be getting.

The frame in question has some old headset cups fitted and with them in the length is 145mm. How much extra would be added with the lower race, upper race and stem? Online research suggests the head tube length on the frame is 115mm (yes, I should have measured it when I was in the shed), meaning the upper and lower cups are 15mm each if equal. So if I get a fork with say a 175mm steerer, will they be enough to take the upper race and stem?

I know the exact answer will depend on the headset and stem, but looking for an approximate idea as too whether 30mm is enough (or 60mm if the steerer is 115mm) for the stem and a complete headset.

I'm talking ahead by the way, NOT threaded.

 

[foz]

30mm is nowhere near enough for the stem. Most are closer to 50mm aprox. The missing races aren't likely to add much, but it's always more than you'd think... At a rough estimate, I'd say that apart from the cups, 5mm for the crown race, another 5mm the the top race, then 50mm for the stem, and that's not allowing for any spacers at all. So minimum steerer length would be the 145mm plus another 60mm = 205mm.

 

[Tootyred]

Look online at the stack height of the headsets your thing of. Use the data from the tallest...plus 50mm for a stem....add it to your head tube.....