thenomad

My stock fork has a steer tube length of 180mm from the bottom of the bearing race (which is pressed on) to the end of the threads, and there are two spacers used stock. The replacement forks come in 175mm and 200mm.
Should I get the 175 and take out a shim and figure it will grip enough threads to be fine or should I go with the 200mm and either slice off 5mm and rethread the end or add more spacers (looks goofy)? I'd imagine there would be enough threads to use a slightly larger one and I could always have the threads extended and the LBS.

Best to go long?

rotharpunc

too long is always better than too short

Charles Wahl

Not necessarily; depends on how tall your two spacers are, what sort of headset you'd like to use or replace old with, and what sort of brakes you have/intend to use. On the whole, for a threaded steerer, I'd advise you to get a fork with a steerer tube that's no less than 38 mm longer than your head tube, and probably no more than 42 mm.

The fine print:
At least one of the things between the top race and the locknut should have a key to the steerer tube. Spacers/washers typically come 2 mm thick (alloy or often, chromed) , 4 mm (Campy alloy), 5 mm and 10 mm (alloy). If you have centerpull, cantilever or whatever sort of brakes that require a stop for the brake cable on the stem/headset end of things, then you need to decide how that's going to be furnished -- you can get stems that have a hole bored through them, or a hanger fixture (Dimension, Problem Solvers, Tektro) that will be clamped to the (most often) threadless tube or (less often) stem shank; with those the headset is "not involved." Otherwise, you need a "C&V" hanger (meaning, no longer in production: Mafac, Weinmann, Dia-Compe, Shimano) whose thickness is part of the headset stack. A headset typically varies in stack height from about 33 mm to 42 mm, including some sort of keyed washer. Many of the classic headsets (Campy, Stronglight, Tange, Shimano), especially those with any sort of rubber/plastic sealing provisions, are at the upper end, with the ones they made at the lower end being rarer. Tange makes a few different headsets, all confusingly labeled "Levin" that vary from 33. to 39 mm; one should always be careful when buying a new one to verify this, because it's often not stamped on the box. Shimano, typically, made high and low profile headsets within the same "line" changing from generation to generation. The Specialized headsets I've seen are rather high profile, and have o-ring seals. Some current-production headsets with cartridge bearings (Tange Falcon, Chris King 2nut) have a somewhat lower profile. When you've figured out all this, then calculate the steerer tube length you need.

thenomad

Oops, it actually has 3 spacers and all have the key.
I have older Royale Compe Brakes (nutted) that I plan to reuse (with proper spacer if needed). I am thinking of getting the carbon fork at Nashbar to save some weight on the frame, but I'm going to weigh the stock Reynolds 531 fork first.

I can get a new headset if needed, I want to use quills to keep the bike looking vintage while just upgrading certain things.

Grand Bois

Velo orange sells 10mm spacers. I'm using two of them on the bike I'm building now. One is drilled for a bell. It's a way to get the bars up a little higher without having a freakishly long stem. The keyed washer goes above the spacers, obvously.

nlerner

I always figured the key washer should fit against the cone, i.e., under the spacers, and thus prevent the cone from loosening. Or maybe it doesn't make a difference?

Neal