So I crashed my awesome columbus tubing trek 900 series frame into a car, which pretzeled the fork and put the frame out of alignment. The fork is not salvageable, but I bent the rear triangle back into alignment. I purchased a replacement fork online, but the axle to crown length is much shorter, about 15mm or so shorter. I was thinking that I could get a little of that back with a taller lower stack height.

So which headset has the fattest lower stack? Thanks.

The old Campy Pista headsets have a low stack height, but these days cost more than a crashed Trek frame is worth

There is a version of the Gran Sport road headset that uses the smaller bearings and has the same low height, but even those are tough to find and expensive.

Check some of the current 1" track headsets that are available. I think the Business Cycles website has specs on stuff like this, or at least could tell you if you email them.

I think the late 90's Campy Record road sets were pretty low as well?

OP wants the opposite: a lower stack that's taller than normal.

Depends on your needs, but I'd consider having the original fork repaired by a good frame builder or a new set of blades put on with the correct dimensions. That is a feasible repair, but probably not fast or cheap.

What's basic problem when you install the new fork? Can you show some pictures? If the blades are too short, you won't be able to clamp in ANY 700c wheel. If they're just a little too short, you might be limited to 700x23 rather than 700x30 or so. Neither of these problems will get better if you space up the crown race to head tube interface.

The only way I can see a 700c wheel fitting in the fork but needing to raise the head tube (top tube tilted down?) is if the new fork has a lot more rake than the Trek fork did, which means you did not buy the right fork. You should be able to find the original rake of your 900 fork by looking up the original brochure for your bike, on www.vintage-trek.com.

My main thought is it sounds difficult to modify an existing headset to get 15 mm of spacing between the crown race seat and the bottom of the head tube, and very unusual for someone to have designed and manufactured such a product in the past. I could barely imagine a headset with 2 or 3 millimeters difference in lower stack height from another one. Bigger bearings might get you a millimeter or so lift. Putting a spacer under the crown race takes the crown race away from the area where it's intended ot have an interference fit, and introduces flex into the steer tube at a very highly stressed area. Putting spacers under the fixed cup reduces the contact the fixed cup has inside the head tube, also compromising strength at a critical point. A millimeter or so at this point might not make much difference in integrity, but it also doesn't get you close to 15 mm extra.

Need pictures, the problem doesn't fully make sense yet.

Road Fan

A low stack that's tall? The new alloy tange levin has a short 33mm stack, velo-orange used to carry it but now I see they have a taller version. If the OP wants extra height can't he just use spacers?

I think you should try to find a fork that fits.

I also think that some people should read the original post twice before responding.

look for headsets with lower cups that have roller/needle bearings.

Probably referring to me, since I blathered on about adding 1.5 cm to the lower stack. -- sorry!

I thought that your response was perfectly appropriate.

I think I'd be looking for a new frameset if I was in a crash serious enough to pretzel the fork and bend the rear triangle.

ok then, must be me. What can I say, mistakes happen.

+1.

Pictures of the headlugs on the OP's Trek, or it shall be assumed that the tubes are kinked behind the headlugs.

-Kurt

I'm just cranky this morning because I have to go to work.

The old fork was the old trek style with the straight crown and curved legs. It had all kinds of tire clearance for fenders and what not with 27" wheels. The new fork is probably a 700c fork. It actually has less rake than the old one as well, so it makes it more stable, but the increased headtube angle negates a little of that.

The frame's top tube and downtube are straight, but there's a dent in one of them from the truck's fender. But it's straight. I turned the frame into a fixed gear because of its err... sordid past. It's not really in the best shape, but I still like it. I rode it around a little and it seems to track straight, and I can ride no hands without any unintended lean.

I'm not trying to make up 15mm, I'm just trying to add a couple mm to it. I have a 13mm lower stack height now, so anything over that would be good.

Regarding the needle bearings headset, would this fit the bill?
https://www.universalcycles.com/shop...17&category=98

When people want to accommodate a higher-stack headset, they sometimes mill a bit of the head tube. Depending on how far the lower pressed-in race sleeve extends into the head tube (some are like 10 mm, others more like 6), maybe you could have a spacer made (30.1 mm inside diameter) that would fit between the race and the head tube bearing surface. If a machinist made it, you could even have the outside of it radiused, like the bead on some of the old Nervex lugs. Of course, what you add on the bottom, you have to give back on the top!

Headsets with cartridge bearings on the bottom have a little more stack height, but I don't think it's enough to make a difference. Velo Orange has a nice one.

The problem I had when I replaces a 27" fork with a 700c fork is that I had to find a short reach front brake that matched the long reach brake in the rear. I don't like Weinmann/Dia Compe centerpulls, so I ended up mixing two sets of Tektro dual pivots from a bike swap. I wanted to try dual pivots anyway.

https://cgi.ebay.com/Serrotta-Titaniu...09125002r37604

I found this, it adds 2cm to the stack height. Who thinks this is a totally bad idea and I will kill myself using it? I also have access to a machine shop, so I could make my own out of some high-strength steel if it would be stronger.

Trek actually made a very wide range of forks over the period 1977 (or so) through the mid/late '80s that look like that, with different rakes, lengths, steer tube lengths, and tubing types. It wasn't just one model, and there were hundreds of thousands of them. There weren't a lot of Columbus ones. There are a lot of current builders who could get replacement Columbus blades and install them in your existing fork crown, and it would end up at least as good and sound as Trek's original.

What does "increased headtube angle mean?" If it's not the same as it was when the bike was built, you have damage that might be very dangerous and absolutely needs to be assessed by an expert.

Why are you trying to add a few mm? Is the steer tube on the new fork a little too long? To accommodate a few millimeters you can add an extra spacer or two between the upper fixed cup and the locknut. This would not disturb the build up of the lower bearing set. That lower bearing set is one of the most highly stressed items on a bike, and needs all the help it can get.

What is the serial number of your frame? I'd like to look it up on Vintage Trek and find the frame specs, and see what trail it was designed for. If it was designed for say 55-60 millimeters with the original wheel, then I really think you'd be best served by getting a fork with the rake Trek designed in and preferably a similar crown to axle length. Making the steering slower (higher value of trail) might really not be a good idea. Another alternative if your new fork is steel is to have a qualified person re-rake your new fork to have the same rake as the old one. This will likely lower the front end a bit, but will get you much closer to what Trek designed it for.

I had a Trek 531 fork re-raked in the opposite direction, no problems no worries. I can even send you to my guy.

Good advice. My Galli needle bearing headset from 1981 has a 19mm lower stack. This helps in giving the frame a slightly steeper seat angle.
I am considering replacing my 1981 frame. Does anyone know which threadless headset has the highest lower stack?