How easy is it to swap a press in steerer?

[Anthony]

Hmm.... this is a bit of a touchy subject.
Problem might lie in the possibility of the steerer being inserted into a hot crown during production, as the pressed-in steerers on the later Pace forks were. Simply pushing the old steerer out and forcing in a new one can put unknown stresses in the crown-which is why Pace wont swop your steerer unless the whole crown/stanchion assy is replaced.

I don't think that's true of Marzocchi though, is it Tim? Windwave will change steerers for you, and indeed if Marzocchi weren't happy with it, you might wonder how come you can buy replacement Marzocchi steerers, and not just crown/steerer assemblies.

The next question would be whether it's Marzocchi that is unusual in this, or Pace. And in this case, whether Answer is in the Marzocchi camp or the Pace camp.

Incidentally, I was assuming that you would heat the crown and freeze the steerer in order to help get the new steerer in, but I hadn't heard before that you could damage the crown getting the old one out.

 

[justbackdated]

Interesting Windwave will change steerers; I don't know if they are normally assembled in a cold state or what. Also not sure about the structure of the crowns.
The Pace crowns have a shedload of internal milling to reduce weight [and therefore strength?] and were always placed in an oven before the steerers and stanchions at 'factory' temp were pressed in. I am not up on the metallurgy side of things but I know Pace shyed away from changing steerers. It may be just that to remove a steerer required tools/jigs that were not easily available or built. Tolerances always seemed to be high on the agenda too; steerers, stanchions and crown sockets were always a bit troublesome and a lot of the time components had to be 'matched'.

 

[Jbiker]

justbackdated - could I pick your brains? I've got a pair of RC36 Pro Class IIs with a longish steerer, and am in the process of buying a pair or RC31s with a shorter steerer than I'd like.

I was imagining I could swap the steerer (or stanchions) between these two forks. Are you saying that wouldn't work? Or maybe that windwave would do it, but the results might be a weakened fork?

 

[FMJ]

double post

 

[FMJ]

Incidentally, I was assuming that you would heat the crown and freeze the steerer in order to help get the new steerer in, but I hadn't heard before that you could damage the crown getting the old one out.

That's what Marzocchi's fancy term Cryofit means, in a nutshell. I'd remove the legs, throw the crown/steerer assembly and the new steerer in the freezer overnight, pull it out and heat just the crown with a heat gun, then press it out with a hydraulic press. Heat the crown up some more, and press in the new (frozen) steerer. If you haven't got a press and need to take it to a shop with one, take the crown/steerer and new steerer there in a cooler full of ice with the heat gun under your arm.

 

[Dave_H]

last solution is to weld some extra steerer onto it .

Or use one of these?

http://www.dotbike.com/ProductsP4016.aspx?utm_source=google&utm_medium=base&utm_campaign=FGL

 

[justbackdated]

Jbiker-I sent a PM about the PC2/RC31 .

Just to add to my comments earlier; most steerers are butted externally at the base where they flare out to the internal diameter of the headset crown race so in theory once that short wider section is pressed out then the job's a good-'un. Some of the Pace forks with pressed-in steerers used their standard plain gauge 1 1/8" or 1" steerers with a steel shim in the crown socket and therefore would need to be forcibly pushed out for the whole length of the steerer, unless the old steerer was cut off and the resulting stub then pushed or machined out.[still risky as any cuts or deep gouges can cause a failure at this highly stressed area].
The biggest problem facing replacement though is still the tolerance between the steerer and the crown socket-too large a tolerance and the steerer will be loose, too small a tolerance and the risk of cracking the crown. :?