I’ve got an old frame that used to fit me well, but I bent the fork in a crash and no longer have it. It’s a decent, middle-of-the road 80’s Italian lugged steel frame, nothing exotic. I’m considering rehabilitating this bike, but I’m not sure whether I want to just put any old fork on. I’m concerned about messing up the handling if I get the length or rake wrong. Opinions?
(it’s not made easier by the fact that it’s hard to find old-fashioned threaded forks any more, without pawing through scrap barrels, which is pretty much a crapshoot.)
truer words have never been spoken. try the platform in the back of kraynick’s, or the second floor. i know that there are tons of brand new old stock threaded forks upstairs on a big rack lining the wall.
Do you still have one or both wheels so you can tell what size wheels it’s built for?
Since it was in a crash, look carefully at the top tube and down tube near the head tube for any sign of bending there, cracking paint and such, before you put any work into it.
If it’s ok, then 2 things you need to determine.
1. at the rear triangle, measure the distance from the middle of the rear dropout to the center of the hole in the bridge for the brake bolt. When you look for a fork, the distance from the fork dropout to the hole for the front brake bolt needs to be exactly the same.
2. measure the length of the head tube, the steering tube on the replacement fork should be about 1″ longer than that measurement. If you find one longer, or new and un-cut, it can be cut, but make sure the threading on the tube ends about an inch below where the top of the head tube will fall.
The rake is less important than these dimensions. You will sort of have to take what you can find.
Yeah, I already went through the pile at Kraynick’s looking for a match to the fork I had. Like I said, pawing through scrap barrels. That was back when I still had the fork, and I didn’t find anything that was an “exact” match. I gave up after an hour or so. Time is money. Twelve years later, he probably has even more stuff, which would improve my odds of finding a match eventually, and lower my odds of finding it quickly. That is, if I still had the old fork.
Length is a tricky one. The dimension you cite, edmonds, is important to be sure that you can use the same size calipers on front and rear. But the fork crown might slope more, or less, than the original fork. And if the fork had more rake, the whole bike would lean forward somewhat, wouldn’t it?
I’ve seen quite a few people riding sketchy stuff that they cobbled together. Knowing that framebuilding theory isn’t my strong suit, I don’t want to be one of them.
From the range of forks that you are likely to find that will have the other correct dimensions, the rake, or offset, is not likely to vary enough to create anything really evil. If you find multiple forks that will work, you could even just eyeball it, if you want quicker steering, pick a fork with less curved blades. If you want slower steering, like touring, look for blades with more curve. The factor that really changes steering is the head angle, that is set by the head tube on the frame, and you don’t need to worry about that, unless there was crash damage.