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Crown race installation

Old 05-29-20, 10:20 AM
  #1  
Chapman
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Crown race installation

I’m slowly building up a touring bike as a learning opportunity. I need to install the headset but I’m confused about the crown race installation because of a bit of material around the steerer tube right above the crown. Should I set the race over this slightly wider section around the sterner tube? (See pictures below). The race is very close to fitting around this section but Not quite. I’m thinking a good couple of knocks would do the trick but thought I would ask you folks first.

Thank you very much!




Last edited by Chapman; 05-29-20 at 10:23 AM. Reason: Included pictures
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Old 05-29-20, 10:27 AM
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Kapusta
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All forks I’ve worked with are a tad wider at the base. The race presses on to that. It is intentionally a very tight fit.

However, all the ones I have worked with are a gentle taper, not such an abrupt change in width.

They make tools for this, though many have good luck with using a pvc pipe that is just big enough to slide over the steer tube. Whack the other end with a hammer to set the race.
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Old 05-29-20, 12:02 PM
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The race should be flush with the top of the fork. Sometimes they can take quite a few good whacks to seat properly. I always measure the I.D. of the race and O.D. of the steerer tube to make sure they're within specs which are usually listed on the headset packaging or can be found on the mfr. website. https://www.sheldonbrown.com/cribsheet-headsets.html

Last edited by Crankycrank; 05-29-20 at 12:07 PM.
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Old 05-29-20, 03:15 PM
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Chapman
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I took the fork to a bike shop and he recommended filing down the “ledge” a hair until the race can be pushed down snug. I’d prefer not filing anything but I don’t suppose it’ll cause any damage.

Does filing the “ledge” sound reasonable?
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Old 05-29-20, 03:21 PM
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trailangel
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I wouldn't file it. I would take it to the best mechanic I know that has the proper die cutter and installation tools.
It's worth a couple of bucks. Do it right the first time. Don't be a hacker.
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Old 05-29-20, 03:56 PM
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Originally Posted by trailangel View Post
I wouldn't file it. I would take it to the best mechanic I know that has the proper die cutter and installation tools.
It's worth a couple of bucks. Do it right the first time. Don't be a hacker.
+1. Proper fork tube cutting tools used to be very common in bike shops but not as much anymore apparently. Keep asking different shops if they can do this until you find one who can. Filing can be done but you're only dealing with fractions of a millimeter on a round surface. Screwing it up is easy.
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Old 05-29-20, 04:20 PM
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Yea , back in the 80s Your famous Italian brands expected the dealer to finish the frame prep .. Campagnolo and the others sold a lot of prep tool sets as a result..
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Old 05-29-20, 05:40 PM
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Originally Posted by Chapman View Post
I took the fork to a bike shop and he recommended filing down the “ledge” a hair until the race can be pushed down snug. I’d prefer not filing anything but I don’t suppose it’ll cause any damage.

Does filing the “ledge” sound reasonable?
The only filing I would do is to perhaps chamfer the corner of the ledge slightly; I would definitely not take anything off of the OD.
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Old 05-29-20, 06:50 PM
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Originally Posted by Chapman View Post
I took the fork to a bike shop and he recommended filing down the “ledge” a hair until the race can be pushed down snug. I’d prefer not filing anything but I don’t suppose it’ll cause any damage.

Does filing the “ledge” sound reasonable?
Why didn't he do it?
You are rounding of the edge so you can get it started that's all.
Take the edge off the crown race instead.
A tiny amount is all you need.
Emery paper would do it .
Once it is started it is easy to tap on.
Slowly and carefully and you can't go wrong.
The race ends up flush and is not affected by the removed material.
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Old 05-29-20, 07:54 PM
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Make sure the race is the correct size- either 26.4 or 27.0
Use the correct tool to install the race on the fork.
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Old 05-29-20, 09:17 PM
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A good bike shop should have a cutter that will cut where the race goes. If the fork is commercially available/part of a frame set more than likely the area has already been cut.

It is a tight fit, a piece of pvc pipe and a hammer should seat the race, try heating the race.
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Old 05-30-20, 11:58 AM
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Originally Posted by rccardr View Post
Make sure the race is the correct size- either 26.4 or 27.0
Use the correct tool to install the race on the fork.
^This^.

Is that 1 inch or 1 1/8 steer tube? If it's 1 1/8, the crown race seat will be 30mm. If you've got the correct headset (for 1/8) all is well. The crown race will have to be driven (hammered) on. Like others said, there is a tool for this, but if you're just building one bike you can use a piece of PVC pipe of the correct diameter. The fit should be snug, but you shouldn't have to pound on it like a maniac to get it installed.....using too much force can cause the crown race to split. If you're sure you've got the correct headset, and it won't go on, you may have to clean up the crown race seat with a bit off sandpaper. Remove any bits of brazing slop or paint that's causing the crown race to hang up.

If you've got a 1 inch steer tube, things can get complicated. The are two common 'standards' for 1 inch headsets: JIS and ISO. JIS uses a crown race seat that's 27mm in diameter. ISO uses a seat diameter of 26.4mm. Most new 1 inch threaded forks are sold with a crown race seat of 27mm. These forks can be use with JIS standard headsets straight out of the box, or can used with ISO headsets after the seat has been milled down to 26.4. The proper way to mill down the seat from 27mm to 26.4mm is to use a special tool (expensive!) made for this, or to turn the forks in a lathe. If you have an ISO headset the crown race seat needs to be 26.4. If the seat is 27mm you have the following options: 1) Get a JIS headset. 2) Pay someone to mill the seat to the correct diameter and use your ISO headset 3) Use the mill bastard method (kluge). The kluge method involves covering the crown race seat in marker ink, working around it with a mill bastard file, cleaning up with some sand paper and checking the measurement. Wash, rinse repeat until you've got the correct diameter and maybe use a bit of green Loctite 680 when installing the crown race. I've done this before, but be warned, I'm not normal.

Pros/cons of dealing with 27mm crown race seat enumerating above:

1) Using a JIS headset.:
Pro: This is the easiest/cheapest method. As stated, the JIS headset works on a fork with 27mm crown race seat with no modifications.
Con: Choice of new JIS headsets are limited. You may not like what's on offer.

2) Having the crown seat milled to accept ISO standard headset.:
Pro: Gives you a big choice of quality headsets.
Cons: Good luck finding someone to do this. Most LBS will not even know what you're talking about, and the ones that do will tell you to leave the frame and fork and they'll do the installation...which can be pricey.

3) Kluge Method:
Pro: Super cheap DIY method.
Con: You will destroy the forks if you don't know what you're doing.

WARNING: The diff between 26.4 and 27 doesn't sound like it's much...it is. If you try and drive a 26.4mm crown race on to a 27mm seat all you will manage to do is ruin the crown race.
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Old 05-30-20, 02:20 PM
  #13  
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Originally Posted by Fissile View Post
^This^.



WARNING: The diff between 26.4 and 27 doesn't sound like it's much...it is. If you try and drive a 26.4mm crown race on to a 27mm seat all you will manage to do is ruin the crown race.
It doesn't even have to be that big of a difference. On one build, I had a fully chromed fork and the crown race seat looked as if it was milled before they chromed it. I know chrome destroys mill cutters. So, I said: "What the hell." and I just slammed on the crown race. When I went to repack the headset around a year later, I noticed the crown race had cracked. So, I removed the race, slowly filed off the chrome and milled the seat just to make sure the bottom was flat. I installed a new race and it's been there for 20 years.

Last edited by gearbasher; 05-30-20 at 02:33 PM.
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