Roundis

The elastomers in my old RockShox forks have perished so I want to swap the forks out for my bike's original rigid forks. I took the caged bearings from the RockShox's crown race and found that the diameter of the cage is too big for the rigid forks. They sit perfectly on the RockShox's crown race but not on the rigid fork. I was wondering, are the crown races different sizes or are my rigid forks just missing a crown race?

I found that the RockShox's steerer tube has an outside diameter of 28.5mm at the threaded section but is 29.9mm just above the crown race. My original fork's steerer tube is 28.5mm all the way down, which then increases to 29.94 mm at the step (don't know what that part is called). My plan was to take the race of the suspension forks and fit it onto my rigid forks, is that the way forward? The picture is of my bike's original rigid forks.

Roundis

Seems I can't post a picture, I just get this error message:
"You are not allowed to post URLs until you have at least 10 posts"

HillRider

It sounds like you have a 1-1/8" threaded steerer on your RockShox and the same on the new rigid fork. You will have to remove the crown race from the Rock Shox and install it on the new fork. This is not a difficult job but you have to be careful not to damage the race while removing and reinstalling it. There are special tools available for both jobs but it can be done with common tools. There are several Youtube videos on how to do it but it might be worth the one time expense to pay a bike shop.

This assumes your new fork has an adequate length steerer for the required stack height or can be cut down to fit.

FastJake

+1 make sure the rigid fork's steerer tube is the same length, and the correct type (threaded in your case.) Though if it's a long threadless steerer tube, you can convert to threadless but you'll need a new headset and stem.

Yes, you need to transfer the crown race to the new fork. I've only ever used a hammer and large flat-head screwdriver. I've scratched plenty of races but never ruined one. You have to be careful and be aware of where you're putting the screwdriver (i.e. NOT on the bearing surface.) Now that I think about it, I should just get the proper tools...

Roundis

Thanks, I'll give it a go. I've sprayed some penetrating oil around the top of the race, I thought that might help for when I come to do it. The forks are the original forks that came with the frame so they will be the right length, I don't know if the headset is original.

FastJake

If it fit the cup before when you were using the Rock Shox fork, it will have to fit when you put it on the new fork. Unless I'm not understanding your question.

Penetrating oil isn't necessary for crown race removal but it won't hurt anything either. You're fighting the friction of the press fit, not a "stuck" part.

Roundis

Yes, it didn't make any sense: I was thinking about buying a new race and was wondering if it would fit, or if I would have to be really careful about buying a new one to make sure it would work? Obviously if I just remove the old crown race and use it again it will be the same crown race / cup meeting as before, as you say.

3alarmer 

.
...it's considered an iffy practice to mix headset parts. Sometimes a crown race can be difficult to remove if there is no place you can get under the lip. If you are throwing away the old fork, if all else fails you can usually harvest the old crown race using destructive techniques on the old fork steerer, but only as a last resort. It is a lot more work than a clean pop off.

Roundis

I got it off thanks, I did some patient tapping and it came off within a few minutes.

I haven't attempted to install it on the other forks yet, I have an offcut of plastic pipe which I'm hoping will do the job, the pipe is too short to clear the steerer tube so I think it will be a bit tricky but should work.

Roundis

Got the race on, thanks for all the help! I'm about to take it for a test ride.

Is it a bad idea to put a recessed nut for fork mounted brakes inside the steerer tube? I bought a cable hanger (Tektro 1277A) for the cantilever brakes but the diameter of the hole in the back of my forks is too small for the hanger's recessed nut. Do I have anything to lose by just drilling the fork out to make the hole bigger? The back of the fork where the nut would sit is slightly radiused. I inserted the nut from underneath the steerer tube and this seems to work, can I just stick with that or is it bad idea?

3alarmer 

... a bad idea because of all the leverage force that gets transferred to the brake bolt when the brake is applied for a standard caliper brake, but with what you are describing (cantilever brakes) it's probably OK. Drilling the fork brake hole opening in the rear is not unheard of in order to mount a nutted brake where a recessed nut brake was formerly installed. So I would do that myself.