Because deforming the metal creates pressure that enhances the lock.
Once the metal has been deformed and thinned in places, it can't create the pressure it's intended to exert.
I will say that I was surprised to find a crush washer in that location. I'm used to seeing them only as seals in pressurized fluid systems (oil or coolant). But by definition, a crush washer is meant for a single use.
And I've never seen a crush washer so thin! Those are practically foil.
Speed comes from what you put behind you. - Judi Ketteler
Mmm. I think that's only on Shimano. My Campy 10-speed lock rings have been used repeatedly with no ill effects.
For 3 days, I get to part of a thousand other journeys.
Pedal wrench and Oakleaf:
What is a cassette and where is this little thin washer you are talking about? Thanks in advance.
The cassette is the rear cog cluster. The lock washer is between the cassette and the lock ring, and is actually attached to the lock ring. You'd have to pry it off the lockring to get it out.
http://www.parktool.com/repair/readhowto.asp?id=48
Frends know gud humors when dey is hear it. ~ Da Crockydiles of ZZE.
Last edited by SadieKate; 08-10-2009 at 08:30 AM.
Frends know gud humors when dey is hear it. ~ Da Crockydiles of ZZE.
There's a crush washer in my 105 cassette. Shimano's exploded parts fiche doesn't even show it, but it's there. As I said, it's extremely thin, maybe half again the weight of heavy-duty aluminum foil. It goes under the "wavy" lock ring. The old one was definitely permanently deformed. I guess if it's not in the parts fiche, maybe it isn't necessary??
Don't know about any other brands or models, but I guess I'd be surprised if all Shimano cassettes didn't have them.
ETA: off topic, but hmmmmmm - Shimano's site says not to use the Ultegra cassette with a triple crank. Didn't know that. If Ultegra had been available in 11-25 as I wanted, I would've gone that way. Lucky.
Last edited by OakLeaf; 08-10-2009 at 08:46 AM.
Speed comes from what you put behind you. - Judi Ketteler
We're looking directly at an XT cassette. Between the lock ring and the 1st cog (both of which have serrated or knurled edges - what you call wavy?), is a washer. It is made of paper thin steel and is slotted into the threading of the lock ring and it is not meant to be removed.
We don't think of it as a crush washer. It is not thick enough or designed to deform. If you try to pry one off, it will behave like spring steel and it looks like chrome-plated spring steel. It returns to shape when messed with.
I think if it was meant to be replaced everytime you removed the cassette, Park Tool or Shimano would tell you to do it. And Shimano absolutely loves to sell you bits and pieces like chain pins. Not ones to shirk from making an extra penny.
Last edited by SadieKate; 08-10-2009 at 10:13 AM.
Frends know gud humors when dey is hear it. ~ Da Crockydiles of ZZE.
I use this thing to clean the chain. Really handy. http://www.parktool.com/products/det...at=8&item=CM-5
My cycling hero: http://www.cyclinghalloffame.com/rid...asp?rider_id=1
I wash my bikes often. It seems ALL bottles leakI get sticky sugary stuff all over the bike from my long training (8+ hours) rides. My bike also gets filthy from commuting. I use a hose and dish wash soap (whatever we happen to have). I then wipe it down with either Finish Line Teflon or Pedros Bike Lust.