timg7

Dear Group,
Does anybody know where to buy a spoke-protector in Europe? Preferably in France or UK.

ChainReaction (the usual recipient of my disposable income) doesn't seem to have them, though I'm not 100% sure I've got the correct search term. The piece I'm looking for is a plastic disc which sits between the cassette and the wheel, and mitigates the damage should the chain jump off the largest sprocket. A Google search turned up the synonym "Dork Disc" and many recommendations not to use them for cosmetic reasons. But of course Cyclocross is a tough business, and aesthetic arguments carry less weight when bike and rider are both covered in a thick layer of mud!

thanks,

Cynikal 

I think you are the only person to ever seek one of these out. Check with a bike shop, they will probably pull one out of the waste bin for you. When you get it, embrace it. Put a bunch of stickers on it or paint it pink or something

unterhausen

someone that rides around here has a really nice black plastic dork disk. I don't see anything wrong with them myself, I've known a couple of people that trashed frames by shifting into the spokes.

M_S

I would go into a Cannondale dealer and get one of those huge black ones--like twice the diameter of the cassette--that they were shipping with some of their carbon road bikes for a while. Not only because it will look sweeeeet but realistically spoke protectors only keep the chain from jamming in the spokes, which only really happens IME if the derailleur is maladjusted. In the case of a severely damaged derailleur or hanger, it's the derailleur cage itself that goes into the spokes, and those enormous discs are the only thing which would have any chance of stopping it. Still probably wouldn't work.

R900

Most dealers should have plenty laying around, just go ask for one. I think it could be a worse mess in a muddy race, that plastic disk packed with mud against the cassette. Anyway, correctly adjusted you shouldn't have any problems going without.

Andy_K 

You'd think not, but once you get enough of the right kind of mud involved, anything can happen.

Case in point:



(I know I've posted this picture a lot, but it's easier than describing it.)

I don't know exactly what happened here. I had gouges in the spokes as far as halfway to the rim, but I don't know if those came before or after the gouges closer to the cassette. It may be that a dork disc wouldn't have prevented this. It might have, but then again it might collect enough mud to cause something like this. In any event, this made me considering getting a dork disc, but I haven't done so yet.

I'm confident the derailleur limits were set properly before this happened. My best guess is that the derailleur bent and then got pulled into the spokes to be shredded.

timg7

Nice disaster pic! It looks like the outer casting of the parallelogram has snapped there. Assuming there wasn't a defect in the metal, that would have required a terrific amount of force. Did the fracture look fresh?

timg7

It's true I've never chewed-up the chain on a well-maintained bike. A spoke protector saved me once when riding a hired bike in the himalaya, but the derailleur (indeed most of the drive-chain) on that bike had been badly mangled and then repaired. And when I say repaired, I mean I hammered it back into shape with a rock. Yes, I was a looong way from the nearest LBS.

Andy_K 

Yeah, the parallelogram snapped, the arm broke in two places, the horizontal dropout adjustment screw was sheared and the derailleur hanger bent. Amazingly, none of the spokes broke, though most of them had some pretty deep cuts. Less amazingly (considering the oxygen debt incurred in a CX race) I didn't even notice it happening. I thought I had just dropped the chain, got off the bike to fix it and found it as above. All the breaks were definitely fresh. It took a pretty fair amount of force (relative to my hand strength) just to get the pulley out of the cassette, so I can only imagine the force it took to cause this kind of damage.

M_S

Andy, your picture illustrates my point. Every mangled derailleur I've seen has either gone into the spokes itself, or destructed in a different direction. I've never seen just the chain pop over the cassette into the spokes on an adjusted system, which is all those things protect against.

But heck, if the OP wants one, it won't hurt anything.

Andy_K 

That, I would believe. I got a chain behind the cassette recently, but I'm pretty sure it was the result of my chain being too short combined with accidentally shifting onto the big cog with the chain on the big chainring. But I thought they were supposed to keep the derailleur in check too. I admit that I very well could be wrong.

fietsbob

I have on on my touring bike wheel ..

Wheelbuild detail. spoke pattern in rear wheel should be radiating clockwise
on the side nearest the gears,so as to not jam hard in, pulled tighter by the spoke pattern.
if there is an overshift.