I need to replace a vintage cyclocross fork. I want to retain the lugged crown and threaded steerer of the original while having fender mounts and 80mm canti-stud centers. I have found a new fork that is close to ideal, except it is only sold with a threadless steerer (both 1 inch and 1 1/8 inch are sold). I already know that you can't just thread a threadless fork due to the thinner wall thickness of the steerer.

Can an experienced framebuilder replace or section-in a threaded steerer?

You would be better off having a framebuilder build you the fork you want.

As nice as the bike is, investing an additional $400 on a custom fork would not be a sound decision.

Here's my take FWIW.

If the steerer is brazed into the fork crown with brass filler, removing the steerer using heat is likely to compromise the structural integrity of the crown. If it was silver brazed, there's less of a risk. So, depending on how it was brazed will determine how to proceed.

If brass filler was used, the old steerer can be cut off flush with the top of the crown and the crown hole precisely line bored in a well equipped machine shop to remove the remnants of the old steerer without using heat. A new steerer can then be brazed into the bored hole in the crown.

New threaded 1" steel steerer tubes of various lengths are readily available from Nova and other suppliers at low cost (~$20), but whether this is economically feasible is a big question considering the machine shop costs and the cost to repaint the fork.

My guess is that not many framebuilders or machinists would want to tackle this because of liability issues.

I've heard of steerers being lengthed by cutting the steerer in the middle and welding a longer threaded section using an inner sleeve to strengthen and align the new section. This reduces the risk of failing at the crown and also means no repainting.

We might have something to fit the bill that isn't going to be $400.00 and will be custom built to boot... send me a pm.

This could work with a long steerer, but the butt joint and inner sleeve will be above the internal taper and that will limit the length of the steerer the quill stem can be inserted into. Most steerer tubes are butted (2.3mm walls) at the fork crown end and have a 30mm taper between the 50mm butt and the top section with 1.5mm walls. Also, the wall thickness of the threadless steerer where the butt joint is will have to be the same as the wall thickness of the threaded steerer for this to work.

I remember a thread on one of these builder forums complaining that modern threadless steerers are overbuilt and their wall thicknesses haven't changed from the threaded steerer days. So I measured the thin section of a Columbus 1 inch from the 80s and compared it to a Nova 1 1/8 that I just put together. They were both 1.5 mm thick. If you have a way to find the thickness before you buy, you might be able to get it threaded yourself. Also, on Nova's site, the butt profiles of the threaded and non threaded are the same.

True, but the threadless fork he's thinking about buying is a Surly. Surly's website has a very strong statement about threading their threadless steerer:

It's pretty clear Surly's threaded steerer is thinner than 1.5mm.

Actually the fork I'm considering is the Soma Classic Curve, but the same applies. I emailed Soma asking if their fork could be threaded and a firm "NO" answer came back with the same reason found on the Surly website.

I'm not sure that there is much of a technical issue with replacing a steerer, but the trick is to find a knowledgeable framebuilder that would do such a repair. I can think of 3 possibilities. Yellow Jersey, Franklin Frames, and Bilenky. Rody at Groovy has the steerer splicing video on his blog, but I'm not sure he would sign up for this particular task. You could ask.

I think Bianchigirll had this done. You might PM her about it.

Need someone to Machine out the old steerer from the fork crown so its still straight when done
with a 1.0" drill bit , set up on probably a Big Drill press ,

or possibly chucking up the drill in the lathe and bringing the cut down fork into it.

to remove just the old steerer tube without the crown race being disturbed

takes a bit more heat to remelt brazing material, in a finished heavy part like fork crowns and Butted steerers
than it was to reach it's melting point in the 1st place..

Just to check, I would try to slip a stem in the Soma steerer (if you can get your hand on one at the LBS). If it fits *correctly* it could be tapped with a piloted tool (as JD Thompson showed in your other thread).

Otherwise, yes it's possible. If your headtube is long enough the simplest would be to splice the steerer. Welding as Groovy Cycles does is probably the way to go but you could braze the inner sleeve too. To remove the entire steerer, a good way is to cut it above the crown race, then slice through to the brass line in a few sections and then heat them individually to peel them off. That would minimize the heat input. But that seems time consuming and will likely be costly... I would call some framebuilders to check. I suspect drilling it out would leave an oversized hole.

Would it be possible to swage the steering tube down to 1 inch and thread it?

The steerer tube O.D. is already 1 inch. The problem is that this threadless steerer tube has a wall thickness too thin to safely thread.

If it was me I'd just build a new fork.



Seems that the original was built to a lighter road / race specification, is a tad bit narrow in it's brake spacing, and lacks mounts for fenders and a crown mounted canti hanger.

Buying and retrofitting a fork is a lot more work than it's worth.

If it was me, I'd buy a threadless headset and a 1" -> 1.125" stem shim to open up the universe of 1 1/8" threadless stems to you, and just run the thing threadless.

Seems like a lot of work for an aesthetic decision. In a lot of ways I prefer a threadless setup- you can fix a loose headset with a 5mm allen key.

Yes, a new fork, built to order, is the best option. I'll have this done over the winter.

Michael, I had a new fork built by Ralph Ellis at Ypsilanti Cycles a few years ago. It was way less than $400 as charged by the well-known builders like Mitch Prior and some other big names, has the custom features I wanted, meets my length/offset specs, and rides real nicely. Ypsi Cycles can be reached at (734) 482-7881. Not the grandest of materials (blades are Dediaccia Zero, I think), but it works quite well.

He might be willing to do the cutting/boring method suggested by Scooper, as well.

But there are a lot of good choices out there.

Have you looked at the forks available from rivendell? they used to list them on their website, but it looks like they are hidden now for some reason. I would call or email them and see if they have any off the shelf ones. They will be more expensive than the Soma parts, but are better quality.

There was another Sheldon fix.. headset , threadless,... tall steerer tube-spacers, just the last bit threaded .
a through threaded nut and the top locknut .. secures the adjustment ..

and then a quill stem is still usable..

I'm not sure how a 22.2mm quill stem designed for a 25.4mm O.D. steerer with 1.5mm walls would work with a threadless steerer having significantly thinner wall thickness. Would the stem ever expand enough in the larger diameter I.D. steerer to be secure?

22.4!

I'd imagine a quill stem could make up .2 of a mm handily. For those thinking in inches, this is less than .008. FWIW, the tolerance for copper plumbing fittings is .005", so it'd be a little loose of a fit, but completely possible to make work.

Uh, I know that.

What I'm suggesting is that if the threadless steerer has 1.0mm walls (as many threadless steerers do) instead of 1.5mm walls, 25.4 - (1.0 + 1.0) = 23.4mm. A 22.2mm quill stem would have to expand 1.2mm and that may be too much space for it to cinch the walls securely.