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How can I tell if a crown race is 26.4 or 27mm?

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How can I tell if a crown race is 26.4 or 27mm?

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Old 06-24-11, 09:22 AM
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Beach Comber
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How can I tell if a crown race is 26.4 or 27mm?

Its damaged beyond measurement. Any attempts to remove it further just makes it worse. I'll probably replace the entire fork, but its an early 70s bike-boom ride from a company long gone, I'm not sure what size the race is.

Other than just ordering a 27mm and turning it down if it doesn't fit, are there any tricks to determine proper size? As luck would have it, I don't have any spare laying around to try a dry fit on.
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Old 06-24-11, 09:45 AM
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I assume they're talking about the crown race size on the fork. Measure with your caliper?

It seems whenever you replace a headset the crown size is not the one you need. I just went through that on a bike I'm working on: I just bought another headset. The larger size can be reamed to the smaller size: most bike shops have the tool, or I've filed them down before, but that's a big pain.

There is a tool to successfully remove the crown race from the fork...
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Old 06-24-11, 09:52 AM
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Swapped the numbers - should have been machine 26.4 to 27. Too much multitasking.
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Old 06-24-11, 09:55 AM
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Originally Posted by Beach Comber View Post
Swapped the numbers - should have been machine 26.4 to 27. Too much multitasking.

No, you'd have to add material and machine to size to go from smaller to larger on the fork.
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Old 06-24-11, 09:57 AM
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There is a tool to successfully remove the crown race from the fork...
Yea, but it seems every time one of the neighbors kids wants to paint their bike, they start off with a really big screwdriver and hammer.
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Old 06-24-11, 10:32 AM
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I vaguely recall seeing a few forks with a 1 piece crown/race. Are you sure its not one of those?

In general there's no real way if telling without removing it and measuring. Also, a 27mm fork can be filed down to 26.4, I suppose you could shim a 26.4mm fork up to 27mm.
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Old 06-24-11, 10:58 AM
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This thread is full of the Lulz.
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Old 06-24-11, 11:06 AM
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Digital calipers, under $20 at Harbor Freight. Every C & V mechanic should own one. Too much variation bike to bike, model to model, brand to brand. Why guess?

I use mine all the time.
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Old 06-24-11, 11:21 AM
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OK, the crown race and what looks like nothing more than a decorative cap fitting over the lugs and base of the fork came off in one piece. Suprisingly, the fork itself looks fine. Even what the cap covered doesn't look that bad, machine wise. I guess what looked like a possible steering tube bend I was just a bad fitting between crown race and lower headset?

Anyway, I didn't realize how cheap the crown races were. The 27 fit. Everything went back together and the kid is happy now.

wrk101 - I hear you loud and clear. Its the next item on the list.
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Old 06-24-11, 11:37 AM
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Bill is right, digital calipers are indispensable. That said, measuring the inside of a seat tube or the inside of a race is difficult and inaccurate.

Also, spring for the 6 inch version.
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Old 06-24-11, 01:05 PM
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Originally Posted by ColonelJLloyd View Post
Bill is right, digital calipers are indispensable. That said, measuring the inside of a seat tube or the inside of a race is difficult and inaccurate.

Also, spring for the 6 inch version.
+1 They often have the 6 inch or larger on sale. I picked up an 8 inch. 6 inch would be plenty, but I would not get anything less than that. Figure the 126mm spacing on rear drop outs = ~ 5 inches. Sure, you don't need digital calipers to measure drop out spacing, but why not have something that will handle the job.

Yep, the 6 inch is on sale right now for $19.99; download a 20% off coupon, and you will get them for $16.


http://www.harborfreight.com/6-inch-...per-47257.html
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Old 06-24-11, 06:43 PM
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DIGITAL calipers in C&V? Perish the thought!

For true C&V you use this:

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Old 06-25-11, 12:49 PM
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New a guy who used a 27 on a 26.4 and just JB welded it in place and ran the bike without any difficulty for 15 years...

I would not do this but...
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Old 06-25-11, 02:03 PM
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Vernier FTW!
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