himespau 

I'm trying to build up a bike from frame/fork and running into all sorts of problems. First, the seller misrepresented the frame construction (probably Columbus SP not SLX, not a big deal), frame model (likely Colnago Super not Superissimo), rear triangle spacing (128, not 130), and seatpost size (27.0 not 27.2). Not much of a big deal other than the fact that I have several spare 27.2 seatposts and no 27.0 (well, I didn't until this week, now I have one to use). All this after the first used frameset I'd bought had a BB that no one has been able to remove (long term plan with that is to get the shell cut out/replaced if the cost isn't too bad)

My current problem with the Colnago I'm trying to build up is the steerer. It's clearly had a headset mounted on it before and it matches the frame (Colnago cutouts on the fork and engravings on the dropouts) and has the frame size engraved on the steerer. It's a late 80's/early 90's Colnago with a 1" threaded steerer, so I just figured it'd use a standard headset with a 26.4 mm crown race. Ordered my usual Campagnolo record headset, tried to put it on, the setting tool couldn't get it down very far and then it caused the sides of the crown race to chip off.

I looked at my crown race setter (it's ~10 years old Nashbar branded) and the place where the adapter interacted with the crown race looked a bit chipped like the chromed surface was peeling, so I figured the setter was past its lifespan. I grabbed my backup Record headset and went to the local bike shop. They put it on the steerer, grabbed their Park crown race setter, a few taps with the hammer, and they've chipped off the sides of another fork crown race.

Now, this is getting expensive.

They said the tolerances were probably too tight and it was probably because of the chroming on the Record crown race made it slightly smaller inner diameter than needed. They said I should get another one and try to very slightly wear back just a touch with some emery cloth or my dremel.

I asked if it was possible that the steerer was just too thick at the seat and needed to be milled down with a crown race cutter. They said no because that might help with this headset, but I'd be in trouble if I ever wanted to change headsets again and the steerer was now too small and the fit was loose. It couldn't be the steerer that was the problem because a headset had clearly been mounted on it before.

So I went home, finally dug out my calipers and both chipped crown races had an inner diameter of 26.4 just as they were supposed to, but the steerer at the base was running 26.7 rather than the 26.5 or so that they usually do for a tight fit.

The headtube races pressed into the frame as expected, so that sizing seems right, it's just that the headset is a touch bigger than expected.

What should I do?

Should I just get another Record crown race and try to remove a little material from the inside as the mechanic suggested?

I also have from the 90's a shimano 600, shimano dura ace, and a Campagnolo Veloce threaded headset. Are any of these more likely have enough give to get them to work with the thicker steerer? I haven't looked at any of the shimano headsets, but the Veloce definitely has more metal and might be more likely to survive the loss of a couple 10ths of a mm if I were try to remove some material from the inside.

Should I just try to find a different shop that has a crown race cutter and see if they'll mill the steerer down to 26.45 or whatever it is? Or was my mechanic right and I should leave the steerer alone?

Reynolds 

I'd measure the steerer with a micrometer and cut it to correct size if needed.

oldbobcat

Here's a link to Sheldon Brown's cribsheet. It shows crown races from 26.4 mm to 27.0, and suggests milling down. I suggest taking the fork to a machinist. As long as you're not milling into the steerer tube itself, the crown should not be compromised.
https://sheldonbrown.com/cribsheet-headsets.html

An alternative might be this cartridge bearing headset from Velo-orange.
https://velo-orange.com/collections/...earing-headset
It has a 26.4 mm split crown race for easy insertion. If the cartridge bearing will seat properly over the slightly oversize split, you have a winner. The other caveat is the stack height. Your steerer might be too short to support the taller bearing plus lock nut.

If it were mine, though, I'd mill it down.

tFUnK

Maybe you need a 27.0mm crown race?

himespau 

Yeah, the collar where the crown race goes is ~26.68-27.74 depending on where I put my digital calipers on it. Given that they're cheap digital calipers, I'd say the level of accuracy says I should call it 26.7. How would you go cutting it down?

A 27.0 would be too big as the collar at the bottom of the steerer is only 26.8

The steerer tube threading is cut to the right diameter for the threaded parts at the top of the headset and the headset races fit as expected into the headset, it's just that that collar is about 0.1 mm too thick all the way around.

Because it's a late 80's Colnago, the only one of those sizes that would make sense other than ISO would be ITalian which is 26.5 rather than 26.4, but that seems like it'd still be a touch small. Might work if I could find an old Italian threaded headset though. I just don't see it being Austrian or East German standard. Unless the whole fork is an elaborate fake.

I don't know if older crown races had more "give" or weren't machined as tightly so that there was one that worked or what, but the Record ones I had were too thin/brittle to handle a couple whacks with the setting tool.

I seem to recall reading that, back in the day, that there were some crown races that were machined super tightly and it would be routine for people to have to get their steerer chased and faced by a shop before installing those (maybe when Chris King ones first came out?), so shops used to commonly carry that VAR or Campagnolo tool for doing that. It may be that I need to find an old shop that still does - those tools (or the Park CRC) are not cheap even used on eBay. I don't know of any old shops around here, but they may exist or some new shops may do it still if that's what I need to do.

That's why I didn't know if there were older headsets known to have a little more give in them (or if it was safe to do the mechanic's suggestion and take ~ 0.1 mm off all the way around from maybe my Veloce crown race that's got a lot more metal in it than the Record or 600 or Dura Ace crown races).


I'd forgotten about the Velo Orange headset. I'd looked at that for a different build years ago, but didn't have the available stack height then. I'll have to measure to see.

himespau 

Yeah, the collar where the crown race goes is ~26.68-27.74 depending on where I put my digital calipers on it. Given that they're cheap digital calipers, I'd say the level of accuracy says I should call it 26.7. How would you go cutting it down?

A 27.0 would be too big as the collar at the bottom of the steerer is only 26.8

The steerer tube threading is cut to the right diameter for the threaded parts at the top of the headset and the headset races fit as expected into the headset, it's just that that collar is about 0.1 mm too thick all the way around.

I don't know if older crown races had more "give" or weren't machined as tightly so that there was one that worked or what, but the Record ones I had were too thin/brittle to handle a couple whacks with the setting tool.

I seem to recall reading that, back in the day, that there were some crown races that were machined super tightly and it would be routine for people to have to get their steerer chased and faced by a shop before installing those (maybe when Chris King ones first came out?), so shops used to commonly carry that VAR or Campagnolo tool for doing that. It may be that I need to find an old shop that still does - those tools (or the Park CRC) are not cheap even used on eBay. I don't know of any old shops around here, but they may exist or some new shops may do it still if that's what I need to do.

That's why I didn't know if there were older headsets known to have a little more give in them (or if it was safe to do the mechanic's suggestion and take ~ 0.1 mm off all the way around from maybe my Veloce crown race that's got a lot more metal in it than the Record or 600 or Dura Ace crown races).


I'd forgotten about the Velo Orange headset. I'd looked at that for a different build years ago, but didn't have the available stack height then. I'll have to measure to see.

Because the bike is a late 80's/early 90's Colnago, the only one of those alternate sizes that would make sense is Italian threaded, though 26.5, while closer than 26.4, still is a hair small. I could look for an Italian threaded headset and see if it's any better. I just don't see it using an Austrian or East German headset, even though those are better matches for the size, unless the fork is an elaborate fake (i.e. someone cut the C with a club in it and stamped Ernesto Colnago into the dropouts after the fact).

JohnDThompson 

Take the fork to an established bike shop with a proper fork race seat tool and have the race seat milled to ISO 26.4mm diameter. It shouldn't cost very much or take very long if you just bring the bare fork.

himespau 

Yeah, I think I'l have to call around and see if I can find a shop with one.

cpach

It is pretty normal for a bike shop to have this tooling. They might not only if they're lower volume and pretty new. Milling the the crown race seat to exact spec is a fine and dandy thing to do even if someone found a race that they could cram on in the past. Running the tool isn't going to hurt anything. This is a pretty small job although it's possible some newer/junior mechanics might not be that familar with it.

Retro Grouch 

A bicycle is a simple machine but the devil is in the details. I would definitely try a 27.0 headset before resorting to the use of power tools.

Reynolds 

I'd take it to a shop that had the tool JohnDThompson posted, but if I couldn't find any, a machinist should be able to do it with a lathe. It would cost more though.

himespau 

Yeah, that was my thought. The shop I took it to, the youngest mechanic looked to be at least in his 40's (hard to tell with masks) and the guy working on it had also been working on a Merckx Titanium EX frame that I got with a in incredibly stuck BB (he told me that it was the 2nd or 3rd BB in 25+ years of doing this that he couldn't get out), so I figured they'd have the experience/equipment. On the other hand, they just moved into a renovated place and all their tools looked almost brand new (and exclusively Park) and they're a chain of Trek stores, so maybe they don't see too many other things. In the past, when I dropped my 1990 Concorde Aquila off, when I went to pick it up, they were like, "where you that guy with the Campy bike?" as if Campagnolo is not something they see much of.

Anyway, they told me that doing this was a bad idea, so I figured I must have had bad info from somewhere. Could just be that they're all new enough to it that they're not familiar with the job or it could be that they didn't have the tooling for it anymore and were trying to come up with an alternative way to get to the same end.

himespau 

The race seat is 26.7, so a 27.0 headset would be loose and sloppy on there.

himespau 

I called 5-6 shops, only the last of whom had ever heard of the tool. Once I explained to them what it was and what I needed it for, they all said that they could file it down or I could do it myself. I then asked them if they knew of an old shop that might have it and they kept referring me to other people who didn't have it either. Finally, the last guy knew what it was , suggested someone I'd already tried that had no idea what it was, and then said that he has a machine shop in his basement (he used to be an aircraft machinist), and has been known to turn fork crown races on his lathe for frame builders to get things down to what they needs, so I'm taking him a headset and the fork.

Retro Grouch 

Maybe, but how confident are you of that 26.7mm measurement? "Measure once, cuss twice."

himespau 

Same calipers, measured on multiple different days at multiple points up and down the seat and I did check to make sure it was zeroed first. Checked several fork crown races I had and they were all 26.38-26.43, so whatever it is, it's ~0.3 mm away from that.

JohnDThompson 

OP says his race seat measures 26.7mm, so a JIS 27.0mm race will be a loose fit. Milling to ISO spec isn't a big deal, and opens a wider range of headset possibilities than JIS.

himespau 

I'm just surprised that no one in town seems to have owned (or heard of) one of those crown race seat cutting tools. I know they're expensive (didn't realize how expensive until I went looking to see if I could just buy one), but I guess I knew of them because I'd lusted over one of those old campagnolo tool boxes after the first time I clicked on an eBay ad years ago trying to figure out how a box of old bike tools could be worth so much money.

jccaclimber

Experienced old grouches or not, I feel bad for the capabilities of your local shops. Not only are they incapable of extracting a stuck BB cup they also don’t know how to cut down a fork crown. I do wonder if their hesitation isn’t that it would be cut to the correct size so much as it would be cut to the next smaller standard than what you’re expecting.

While I wouldn’t call it incredibly common, the surfaces on a bike that require a finish ream/face are out of spec. are often enough that I wouldn’t call it uncommon either.

As for which part to modify, I don’t like turning my bikes into art projects by custom fitting parts that should be off the shelf items, so whichever part is non-standard should be corrected. The only exception I’d make is if the fork had been cut incorrectly undersized already I’d consider shimming it back up. Done properly this is fine, but it sounds like your problem is the other way.

It’s much easier to hit the intended tolerance with the made for purpose hand reamer (our local co-op has the Park one) and is a 5 minute job on a bare fork. It’s perfectly doable on a lathe as well, assuming a competent machinist. The only risks there are said machinist being lazy and cutting the race off center, leaving too large a radius at the bottom, or straight up missing in size and trying to call it close enough. None should be an issue if they know what they are doing…but neither should cutting out a stuck BB be an issue for the same person.

tFUnK

Given that the measurement varies depending on where it's measured, I'm still willing to bet you'll be fine with a 27.0mm race (it won't be loose). You'll be well served milling as well but sounds like your shops don't have the capability.

cpach

You don't gotta be ancient to be familiar with this stuff. I'm 35 and have been pro for only about 5 years. This would feel very comfortable to me.

Lack of tooling is likely though. I'd have a hard time justifying buying it if we didn't already have it. It really doesnt come up much. Sometimes it's useful to mill jis to iso.

himespau 

I was definitely surprised the the one shop that everyone said was the oldest around (a Schwinn shop) that said, "oh just file it" and the other shop known for steel bikes that wanted to put it on their grinder. Both of those sound like ways of easily going past speck or way out of round given that I needed 0.1 mm taken off all the way around to get down to the right size.

Since this frameset has been ridden before, I wonder what headset was on there and how it fit. I do think that taking the fork down to the spec size is the right call (assuming the guy can actually do it properly).

Still a bit confused by the first shop that couldn't get the crown race on, chipped a chunk off the side, and just kept trying to get it on (after saying the area that had broken off didn't support the bearings anyway) and then told me to ream out the race without ever bothering to measure to see where the problem was. They had initially seemed pretty competent (my cartridge BB seems to have fused between the threads and the threads of the Ti bb shell when the previous owner didn't grease the threads - I've had several people from many places tell me that can happen, so I don't put that on them) and much of their quibbles (asking me if tire savers were things just to make noise, not being familiar with campagnolo stuff things like that), I chalked down to the fact that it makes me happy to use nonstandard stuff, but maybe I need to be going to a new shop.

Hopefully this new guy is a bit better. He talks a good game (but so did the folks at the last shop, which seemed to have a community following), so I guess we'll see.

As you say, if your co-op can have the tool, I don't get why none of the shops I talked to did. Maybe only working on new bikes made in the last decade or two, has made that less of an issue. We don't appear to have much of a history of cycling here. 15 shops or so now, but they may mostly be a more recent thing. Before moving here, I lived in Boston and my local shop was one of those places that had a back room/basement that, while I'd never been in it, seemed to have leftover and one off bits from long ago. I know they found a couple parts for me that I had no idea existed to solve problems.

himespau 

Yeah, I mean the Park Tool is ~$500 and the VAR is a couple hundred more than that. If it's not something you anticipate doing very often (you only ever sell/work on new bikes), it's hard to justify that kind of investment for a couple $50 jobs a year (at most). That's why I was hoping to find an old shop, figuring it was the kind of job that was once more common.

Russ Roth

This mechanic is incompetent and doesn't know what he's doing. A crown race cutter doesn't make things random sizes, it mills the shoulders of the race to the proper diameter and squares the surface of the race to the steerer. Once the tool is done being used any modern 1" headset should have no problem fitting. I would not be surprised to discover that some flake in the past has whacked a seat onto it in the past and accepted how it worked.
I'm also not surprised that a lot of shops lack this tool, I've used it on Italian bikes in the past but carbon forks and suspension forks are bonded systems that don't get chromed and warped from heat and how many modern bikes don't come with one or the other making it an outdated tool. An old schwinn shop should have had one or look for a local frame builder, they're likely to have one. But if the shop is younger than 20 years old, I wouldn't be surprised to find they don't have one, really is more of a 90s and earlier tool or modern frame builder tool.

Spaghetti Legs 

I’ve seen where the the fork crown is knurled with a tool designed for this to effectively increase the diameter. The tool is probably expensive and your LBS probably doesn’t have it, but you might ask in the C+V section. In your place I would look into that or maybe just use an aluminum can shim to get a 27 on there. I’m pretty sure one of my bikes has a shimmed crown race.