Replacing a fork / threaded headset
#5
Your cog is slipping.



Joined: May 2009
Posts: 26,053
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From: Beverly MA
Bikes: EAI Bareknuckle
Yeah but if the crown race on your new fork isn't the same size as the old one, you may have some troubles. ISO threaded headsets use a 26.4mm crown and JIS headsets use 27mm.
Last edited by Scrodzilla; 01-02-10 at 06:36 PM.
#7
Old fart



Joined: Nov 2004
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From: Appleton WI
Bikes: Several, mostly not name brands.
If you're replacing the unit (as opposed to simply servicing it), you will need to knock the cups out of the head tube and the crown race off the fork crown. Make sure your replacement parts match (i.e. ISO vs JIS dimensions, and overall stack height) before you get in too deep. JIS head tube and fork crown seats are easily milled to ISO dimensions, but going the other way can be problematic. If your steer tube is too long for the new headset, adding spacers is quick and easy, but if it's too short, you're SOL except for a new fork.
#9
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From: NYC / Brooklyn
Exactly. I just got a new frame with 2 forks. I just want to make sure that I will not be running into any unforeseen problems when I switch them out. Both forks have crown races... I'm ready to go.
Thanks again!
#10
that said, what you need to do is (provided you are not crossing ISO with JIS as stated) unscrew the lock nut, then the top cap (removing any spacers), pull the fork out. then you must remove the crown race from the existing fork and put it on the new fork. sometimes this is easy, sometimes this is very difficult without the proper tools. it's made to sit tight and a crown race tool is usually necessary to put it on the new fork, even if you can get away with removing it from the old one with a fat screwdriver and a hammer. the important thing is to NOT DAMAGE the race where it comes in contact with the bearings, and it should sit flush against the crown.
provided you can do that, just add some grease and reinstall. of course you have to know how to properly adjust a threaded headset. do you know how to do that? if you don't you will ruin your headset by either having it too tight or too loose.
#11
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From: NYC / Brooklyn
#13
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