Bicycle Mechanics - Crown race measuring
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01-17-10, 12:29 PM
I am trying to measure the inside diameter on an older crown race and can't find any reference on which place to measure. Obviously on the inside of a press fit crown race you will have a ring that is smaller and the rest is larger. Do you measure the smaller diameter or the larger diameter???
01-17-10, 12:47 PM
You're trying to figure out the diameter of the crown race where it would seat on the fork. That would be the "inside" diameter as such. If you think about it one measurement is clearly useless and one is not.
01-17-10, 12:56 PM
Inside diameter is the inside diameter. Like this:
This crown race is 26.4mm.
01-17-10, 01:16 PM
I've never seen one with two inside diameters, but obviously the smaller would be the one of relevance.
01-17-10, 01:29 PM
Thanks for the replies. The crown race I am measuring is smaller where it seats on the fork than it is the rest of the inner diameter. Like a small ring on the inner diameter. Using the smallest diameter it reads around 26mm (my calipers are not very good) so I assume it is a 26.4
Accurate digital micrometers are cheap at Harbor Freight and similar. I got mine for under $10. A good investment if you are going to work much on bikes.
01-17-10, 05:12 PM
You dimension "L" in this diagram:
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