Crown race "stretching" ?

[cid499]

I picked up a used CK off the board here (thanks Kelly) for a good price. It came with a Ti baseplate (crown race), but when I went to install it I found it had too much clearance and could slip on and off the steerer tube with ease.

I measured the crown race inner diameters for the CK baseplate and for the old crown race I removed.

Chris King baseplate I.D.:
1.1900 in = 30.22600 millimeters ~30.2 mm

Old crown race I.D.:
1.1815 in = 30.0101 millimeters ~30.0 mm

So, my questions:
Is it common for baseplates / crown races expand during installation or removal? If so, is a Ti baseplate for susceptible to this than steel?

I guess there's also the chance that it could just be a custom overbored crown race from CK...

[rice rocket]

That's a pretty big difference.

What's the OD of the steerer at the base vs the ID of the crown race? Are you using calipers? Chris King specs them as 30.1mm, but who knows what their acceptable tolerances are.

Keep in mind that calipers aren't a good way to measure internal diameters. To do it accurately, you should be using bore gauges like this:

http://www.automechanicschools.net/img/thumb/bore%20gauge.jpg


Oh, and if you're within .010, there's variety of setting compounds you can use to keep it in place. 3M Retaining Compound will "fill gaps" of .010, but it's pretty hard to remove should you decide to. I've used it more than I care to admit to cover up some botched machining work. :rolleyes:

http://solutions.3m.com/wps/portal/3M/en_US/Health/Safety/Products/Related/?PC_7_RJH9U52300A9E023IJD0GR3O74_nid=2RGWG9765Hgs6 51JNCZ61CglJBWZRT778Mbl

http://multimedia.3m.com/mws/mediawebserver?mwsId=SSSSSu7zK1fslxtUO8_BPx2xevVSe ChshvTSevTSeSSSSSS--

[echelon_john]

Chris King makes aftermarket crown race rings for when the crown is slightly undersized; I needed one on my Sachs. Look on their site under 'parts'; they're about $10, I think, and better than a kluged adhesive solution or trying to knurl the fork crown.

from the CK site:
Baseplates with undersize bores of up to minus .2mm (-.008") are also available to accommodate non-conforming fork steerer tube mounting dimensions. Please contact our friendly customer service team to ensure the correct sizing for non-conforming fork steerer tube mounting dimensions.

For fork crown and downtube interference issues such as those you may find on 29ers and extra-small size mountain bikes we offer a +5mm baseplate in a stainless steel 1-1/8" size.

Tech information is available on our site:
Headset Tech

Please contact us with any small parts questions:
info@chrisking.com or 800.523.6008

[97CSI]

That's a pretty big difference.
Oh, and if you're within .010, there's variety of setting compounds you can use to keep it in place. 3M Retaining Compound will "fill gaps" of .010, but it's pretty hard to remove should you decide to. I've used it more than I care to admit to cover up some botched machining work. :rolleyes:
The problem with using any of these is centering the race. One side might be touching the steerer tube, leaving a gap on the other with the result of uneven forces on the bearing and wonky steering and accelerated wear. Buying a new crown race from CK is the right solution.

[oliver1850]

Sounds to me like the King crown race you have has either been polished out, or was oversized to begin with. Perhaps someone fit it to a fork that had never been finished to size.

I don't know if there was a JIS 1 1/8" crown race standard, but the 1" JIS is 27mm compared to the more usual 26.4mm.

Cane Creek specs for fork crowns list 30.015-30.075mm as the acceptable range. There is a very nice tech doc on their site that lists standards for fork crowns and head tubes.

[oldpotatoe]

I picked up a used CK off the board here (thanks Kelly) for a good price. It came with a Ti baseplate (crown race), but when I went to install it I found it had too much clearance and could slip on and off the steerer tube with ease.

I measured the crown race inner diameters for the CK baseplate and for the old crown race I removed.

Chris King baseplate I.D.:
1.1900 in = 30.22600 millimeters ~30.2 mm

Old crown race I.D.:
1.1815 in = 30.0101 millimeters ~30.0 mm

So, my questions:
Is it common for baseplates / crown races expand during installation or removal? If so, is a Ti baseplate for susceptible to this than steel?

I guess there's also the chance that it could just be a custom overbored crown race from CK...

Go to a shop that has one of these-

http://www.biketoolsetc.com/index.cgi?id=2528465&c=Tools&sc=Headset&tc=Crown-Race-Knurling-Tool

[Dave]

There are two standards for the crown race diameter. The OP has a fork built to the JIS standard and the crown race is built to the larger Euro standard.

http://www.parktool.com/blog/repair-help/headset-standards#threadless

[oliver1850]

I checked both the Park and Cane Creek documents and could not find a JIS standard for 1 1/8" headsets, only 1"

[Dave]

I checked both the Park and Cane Creek documents and could not find a JIS standard for 1 1/8" headsets, only 1"


That's because there are two standards, only for 1" steering tubes, which is what the OP is asking about.

1-1/8" steering tubes should all be made to the 34mm diameter.

[oldpotatoe]

I checked both the Park and Cane Creek documents and could not find a JIS standard for 1 1/8" headsets, only 1"

Yep, AFAIK, no such animal as JIS for 1 1/8 inch.

Get a smaller FCR or knurl it dear liaza, knurl it....

[ultraman6970]

I had a similar problem but with a 1inch fork... repainted the fork and now for sure it will fit tight :P

Always u can put some paint in the crown race area once the crown race is in the paint will hold it.

good luck

[oldpotatoe]

That's because there are two standards, only for 1" steering tubes, which is what the OP is asking about.

1-1/8" steering tubes should all be made to the 34mm diameter.

Fork crown race inside diameter(and fork crown race seat on the fork) is either 26.2mm or 27mm(JIS). Cup outside diameter(ID of headtube) is 30.2mm.

Fork Crown Race headset ID on a 1 1/8 inch fork is 30mm...

OP said the ID of the fork crown race was 30 or 30.2mm...so then that's 1 1/8 inch.

I have an idea...let's ask the OP!!

Is it 1 inch or 1 1/8 inch?

Is the OD of the steerer of the fork 25.4mm or 28.6mm??

[Dave]

Oops, I misread that. The OP did give dimensions for a 1-1/8" steering tube, but a new Chris King race should not meausure 30.2mm. Calipers should be plenty accurate to measure that.

http://www.sheldonbrown.com/cribsheet-headsets.html

[oliver1850]

OP has stated that his original crown race was 30.01mm and fit fine.

Therefore he must have a 1 1/8" fork

I think his fork is the right dimension, but his King crown race is oversize, for whatever reason


I think Dave is thinking of the 30.1 mm inside diameter of a 1" head tube.

Here are the specs for the fork crowns (finished diameters that the crown race seats on):


1" std.: 26.43 - 26.49 mm
1" JIS: 27.03 - 27.09 mm
1 1/8": 30.015 - 30.075 mm
1 1/4": 33.03 - 33.09 mm

The respective crown race diameters of the headsets are:

1" std.: 26.4 mm
1" JIS: 27.0 mm
1 1/8": 30.0 mm
1 1/4": 33.0 mm