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Headset crown race won't fit on fork - need LBS reco

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Headset crown race won't fit on fork - need LBS reco

Old 12-22-09, 10:05 AM
  #1  
achoo
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Headset crown race won't fit on fork - need LBS reco

Second issue on building out my De Rosa: the headset crown race (the bearing race that mounts on the fork, at the bottom of the steer and head tubes) won't fit over the mount point on the fork. The crown needs to be milled down to size, and unlike my problem with the seatpost that's fixable with a $10 tool, this tool looks to be in the $400 range.

Anyone have a recommendation for a LBS in Northern Virginia area, preferably Reston/Herndon, that could perform the work? My experience with the LBS's in the area are with jobs like truing wheels and recabling brakes, not milling the forks of high-end frames.
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Old 12-22-09, 10:18 AM
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I have heard that some forks and headsets is a tiny bit larger diameter than others.

I havent heard of a tool to sort this. But theres loads of specialist tools. So I guess there is one.

Have you enquired at a machine shop. would only take a second to lathe the forks to the right size. Get freindly with a machinist and he might do it in his lunch hour for a drink
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Old 12-22-09, 10:34 AM
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Keep calling bike shops until you find someone with the tool. I had that problem with my Colnago.
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Old 12-22-09, 10:38 AM
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Originally Posted by griftereck View Post
I have heard that some forks and headsets is a tiny bit larger diameter than others.

I havent heard of a tool to sort this. But theres loads of specialist tools. So I guess there is one.

Have you enquired at a machine shop. would only take a second to lathe the forks to the right size. Get freindly with a machinist and he might do it in his lunch hour for a drink
Yes, there are tools for this job, but they aren't cheap. Any high-end bike shop should have one, though, and in a pinch a machine shop could turn it down to the right diameter (26.3mm for ISO; 27.1mm for JIS).
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Old 12-22-09, 10:42 AM
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Of the 3 bike shops in my town, I don't think any of them would do this. Good luck!
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Old 12-22-09, 11:53 AM
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Maybe this is a dumb question, but unless the difference is significant, why not increase the ID of the race instead of cutting down the fork?
If the difference is only a couple of tenths then the balls will still have plenty of race to ride on. You could probably do a pretty fair job with a Dremel tool and a sanding drum...just make sure to remove the burrs afterwards.

Or am I missing something here?
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Old 12-22-09, 12:18 PM
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Originally Posted by rccardr View Post
Maybe this is a dumb question, but unless the difference is significant, why not increase the ID of the race instead of cutting down the fork?
If the difference is only a couple of tenths then the balls will still have plenty of race to ride on. You could probably do a pretty fair job with a Dremel tool and a sanding drum...just make sure to remove the burrs afterwards.

Or am I missing something here?
Because that would be thinning the race where almost all of the weight on the front fork rests.
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Old 12-22-09, 12:21 PM
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A dremel would not do a good job of enlarging the ID of crown race. A press fit crown race requires a very round and precise hole with an interference in the range of .002-.004 inch. The other option would to buy a headset with the proper crown race diameter, or take the race to a machine shop that could use a lathe to do the job properly.

The minor difference in the ID would not hurt the strength of the race.

Last edited by DaveSSS; 12-22-09 at 01:50 PM.
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Old 12-22-09, 12:55 PM
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Is this a new DeRosa or an old DeRosa?

If it's an older one, why don't you just buy the correct headset?
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Old 12-22-09, 01:12 PM
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Originally Posted by PlatyPius View Post
Is this a new DeRosa or an old DeRosa?

If it's an older one, why don't you just buy the correct headset?
Pretty much brand new Neo Primato steel frame. The head tube had already been reamed out for a headset, but I forgot to check if the fork crown had been cut down, though.
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Old 12-22-09, 01:25 PM
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I'm not aware of any frame manufacturer that sends out new framesets with the fork crown uncut/milled. That's odd.
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Old 12-22-09, 01:58 PM
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This is a dumb question, but did you get a JIS instead of an ISO 1" headset by mistake?

There's got to be a screwup here, as a high-end frame should not need milling to accept a headset.
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Old 12-22-09, 02:08 PM
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Originally Posted by bigvegan View Post
This is a dumb question, but did you get a JIS instead of an ISO 1" headset by mistake?

There's got to be a screwup here, as a high-end frame should not need milling to accept a headset.
Which is what I was hinting at without saying. lol.
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Old 12-22-09, 04:00 PM
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It's actually not unusual.
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Old 12-22-09, 04:07 PM
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I just paid $25 to have this done and another inch of threads added. The crown race now fits perfectly, but the transition between the old and new threads is a bit rough.
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Old 12-22-09, 05:29 PM
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Originally Posted by bigvegan View Post
This is a dumb question, but did you get a JIS instead of an ISO 1" headset by mistake?

There's got to be a screwup here, as a high-end frame should not need milling to accept a headset.
Standard Campy Record 1" threadless headset.

The steer tube race fits fine. The headtube top and bottom races were a bit tight, but I was able to get them seated by leaving them in the freezer overnight, then warming up the head tube with a blow dryer.
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Old 12-22-09, 05:44 PM
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Originally Posted by bigvegan View Post
This is a dumb question, but did you get a JIS instead of an ISO 1" headset by mistake?

There's got to be a screwup here, as a high-end frame should not need milling to accept a headset.
Except since JIS cups are smaller diameter, and JIS crown races are larger diameter, they would be loose in a frame milled for ISO parts.
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Old 12-22-09, 06:17 PM
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I've seen this "milling" done with a bastard file. That's how I'd approach it, but none of my bikes are worth that much.
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Old 12-22-09, 07:52 PM
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Because that would be thinning the race where almost all of the weight on the front fork rests.
No way. The race is actually pretty wide on the bottom end and the weight rests in the middle of the race, not the inner edge. Like I said, if it's only a couple of tenths, there's plenty of room to increase the ID. If it's more than that, there's a serious headset sizing problem.

I agree that a Dremel would not be the optimum solution, but in the Lab we work with much smaller R/C sized parts and- with proper care- you can make something pretty round if it's round to begin with.
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Old 12-22-09, 08:09 PM
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Originally Posted by tellyho View Post
I've seen this "milling" done with a bastard file. That's how I'd approach it, but none of my bikes are worth that much.
Umm, yeah. Emery board, though.

I had a Homer Simpson moment this evening when I pulled out the fork and noted the thick black paint from the steer tube covering the crown.

Used an emery board to remove every trace of the paint, and DOH! the crown race popped right on.

Paint. Remove it.

Thanks everyone for your suggestions.
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Old 12-22-09, 08:47 PM
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Originally Posted by bigvegan View Post
This is a dumb question, but did you get a JIS instead of an ISO 1" headset by mistake?

There's got to be a screwup here, as a high-end frame should not need milling to accept a headset.
A JIS headset would have a 27.0 mm crown race and would be a sloppy, loose fit on an ISO fork, not excessively tight.

Question for the OP; how tight is the crown race? Most crown races are a firm drive fit onto the forks and the standard setting tool looks a lot like a slide hammer. You should not expect it to just slip on with finger pressure and you may already have the right size race and fork seat area.
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Old 12-22-09, 09:00 PM
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Originally Posted by HillRider View Post
A JIS headset would have a 27.0 mm crown race and would be a sloppy, loose fit on an ISO fork, not excessively tight.

Question for the OP; how tight is the crown race? Most crown races are a firm drive fit onto the forks and the standard setting tool looks a lot like a slide hammer. You should not expect it to just slip on with finger pressure and you may already have the right size race and fork seat area.
It fits just right, now that I got the paint off the race seat on the fork.

Anybody got a good face-palm image? I deserve it.
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Old 12-22-09, 09:06 PM
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Originally Posted by achoo View Post
It fits just right, now that I got the paint off the race seat on the fork.

Anybody got a good face-palm image? I deserve it.
And if there's more paint, you might as well get that faced clear anyways.
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Old 12-23-09, 12:10 AM
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Originally Posted by achoo View Post
Anybody got a good face-palm image? I deserve it.
Yes.

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Old 12-23-09, 02:08 PM
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I had to have my LBS press/drive fit in my Stronglight A9 fork race with a special tool. I think that the race should fit in tightly as did the one I removed from the bike. Same goes with the head tube races.They had to ream the tube and press fit them in. Surprised that many are mentioning that their fork races are just slipping on easily by hand?? Wouldn't that mean that they could develop some looseness later if they do fit in too easily??

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