# Is the plastic dust cover for the cassette important?



## 2 Slow (Jul 20, 2012)

I went for a ride today and noticed that the plastic cover behind the cassette was dislodged from it's normal position and when I got home I realized one of two plastic nipples holding it in place had broken off, therefore rendering the cover useless. 

I removed it from the bike so that it doesn't get in the way of my spokes, but would like to know if it's an important piece and whether to replace it or not.


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## Zoke2 (Nov 16, 2007)

nope ... its commonly called a dork disc for a reason


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## eb1888 (Jan 27, 2012)

The upper limit adjustment on your rear derailleur keeps the chain from going off the largest rear gear and into the spokes. No real need for the plastic guard.


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## 2 Slow (Jul 20, 2012)

Ok cool, thanks guys!


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## -Todd- (Jun 13, 2011)

eb1888 said:


> The upper limit adjustment on your rear derailleur keeps the chain from going off the largest rear gear and into the spokes. No real need for the plastic guard.


Until your derailler comes out of adjustment, sending the chain over the top into the spokes... Just know what you're getting into before you take it off...


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## the-one1 (Aug 2, 2008)

-Todd- said:


> Until your derailler comes out of adjustment, sending the chain over the top into the spokes... Just know what you're getting into before you take it off...


In that case, EVERYONE should get one put back on right away.


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## Bill in Houston (Nov 26, 2011)

-Todd- said:


> Until your derailler comes out of adjustment, sending the chain over the top into the spokes...


Wedging the chain in there, and bending/breaking spokes. One of those things that can save you some pretty serious trouble, but that many people get rid of.


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## CSC (May 23, 2011)

eb1888 said:


> The upper limit adjustment on your rear derailleur keeps the chain from going off the largest rear gear and into the spokes. No real need for the plastic guard.


True...though I have dealt with a crappy LBS upper limit setting on a loaner wheel...and became quite adept at fishing the chain out from the space between 1st gear and the hub (quite a task after the chain hops off during a steep climb...they really get wedged in there).

I would think that a better, less "dorky" piece of hardware would have been made by now...maybe a disc of carbon fiber, with arms that lock onto the hub?


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## heyyall (Nov 10, 2011)

The plastic disc doesn't keep the chain out in the real world. The pressure from the cranks rips through the plastic like a hot knife through butter.


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## ZmyDust (May 13, 2011)

Sorry to jack but can that thing be broken off? (thus not needing to remove tha casette? Or does the dork disc removal require removing the casette?


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## heyyall (Nov 10, 2011)

ZmyDust said:


> Sorry to jack but can that thing be broken off? (thus not needing to remove tha casette? Or does the dork disc removal require removing the casette?


Yes. Cut it with a snips; it is plastic.


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## chaboi (Aug 1, 2012)

Interesting I didn't know that


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## Millfox (Jun 22, 2012)

I prefer to keep it. Screw looks, you never know what might happen on a bumpy ride.


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## heyyall (Nov 10, 2011)

When I broke mine on my first bike, I thought the world was coming to an end. 1000s of miles later, the world still turns without this plastic disk. Just make yourself a promise when the disk is old, yellow, and clunking around the hub as you pedal, that you will cut it out of the wheel.


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## Bill in Houston (Nov 26, 2011)

one time, when i was a young lad, first learning to adjust my limit screws, i went for a test ride and actually shifted the chain up onto the dork disk. i was really confused for a few seconds as to how i could pedal, and the chain could move, and i still wasn't going forward.


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## austburn (Aug 5, 2012)

Just got my first bike, and mine is dislodged as well. It's used, so when I got home, I thought I got jipped. Good to know that all is well.


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## mimi1885 (Aug 12, 2006)

I took mine out but only because I couldn't handle the peer pressure


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## KingofWylieTX (Jul 30, 2012)

All the cool kids around here are replacing the DD with BBF's (big bright frisbees). It is the new bling! Y'all need to get you some!

On a more serious note, I always wondered whaT that thing was supposed to do. Now I'm thinking of ripping mine off, because I've never had my chain go off that way.


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## perttime (Aug 26, 2005)

KingofWylieTX said:


> Now I'm thinking of ripping mine off, because I've never had my chain go off that way.


So you haven't had a bent derailer hanger yet?

(That is what got my chain into the spokes)


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## KingofWylieTX (Jul 30, 2012)

Not yet, but I suppose anything is possible. 

I just replaced my old bike (maybe 2 months ago), so maybe I'll wait until the disk starts to look old before I remove it. I don't remember my last bike having one, so it must have broken off or I took it off after it became damaged. I rode that bike for 19 years - so I don't actually remember what happened to it.


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## DennisF (Nov 4, 2011)

Why is it the higher-end bikes tend not to have the pie-plate thingy?


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## KingofWylieTX (Jul 30, 2012)

@DennisF - (tongue-in-cheek) now I'll have to go see if my new bike has one so I'll know if it's a higher-end bike!! I don't know if does or does not have one, I assumed all bikes have them.


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## jeffscott (May 10, 2006)

2 Slow said:


> I went for a ride today and noticed that the plastic cover behind the cassette was dislodged from it's normal position and when I got home I realized one of two plastic nipples holding it in place had broken off, therefore rendering the cover useless.
> 
> I removed it from the bike so that it doesn't get in the way of my spokes, but would like to know if it's an important piece and whether to replace it or not.


I would not bother to replace it....

It prevents the chain from damaging the spokes if it falls off the cassette into the wheel side.

You should pay a bit more attention and stop pedalling quickly if you think the chain may have fallen off that side, otherwise if you keep pedalling you could grind up some spokes as well.

And yes no matter how you tune up your bike the chain can fall off to the inside.....think bent hanger trees, rocks, sticks twigs...etc.

Mavic SLR's have a spoke protector (high-end wheel), but Shimano STR wheels (high end too) don't have aspoke protector...


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## jeffscott (May 10, 2006)

DennisF said:


> Why is it the higher-end bikes tend not to have the pie-plate thingy?


Most high end builds are going for minimum weight.....and expert rider who will not grind a spoke or too if the chain slips into the spokes...

on the other hand my Mavic SLR wheels did have a spoke protector (very small and light)....I did eventually drop and chain and grind off that spoke protector though.


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## MadBlackHatter (Mar 26, 2012)

ha mine just broke and started rattling around. time to get the snips out


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## NickS606 (Aug 9, 2012)

I'd say that if it is there then keep it until it breaks.


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## bloodninja (Jul 11, 2012)

heyyall said:


> The plastic disc doesn't keep the chain out in the real world. The pressure from the cranks rips through the plastic like a hot knife through butter.


The plastic ring saved me just yesterday, so I'm leaving it on.


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## blockphi (Mar 26, 2012)

Zoke2 said:


> nope ... its commonly called a dork disc for a reason


I always thought it was the p*ssy platter....


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## B1KER (Jul 19, 2006)

I bought a new bike for my girlfriend yesterday and first thing I did was remove all the stupid stickers that are all over it and broke that thing off too. I totally agree with the guy who said the chain just breaks it anyway. I'd like to see the look on the guy at the LBS when you go in looking for a replacement. LOL


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## DennisF (Nov 4, 2011)

KingofWylieTX said:


> @DennisF - (tongue-in-cheek) now I'll have to go see if my new bike has one so I'll know if it's a higher-end bike!! I don't know if does or does not have one, I assumed all bikes have them.


I think we just found the world's cheapest way to upgrade :thumbsup:


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## Bill in Houston (Nov 26, 2011)

After destroying my rear der yesterday when a small rock pushed it into the spokes, I will be making an even bigger dork disk, maybe from a frisbee or something.


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## alexplantman (May 1, 2006)

Let peer pressure and looking cool drive your major decisions in life and here's one...Are you going to remove it to blend in with your buddies?


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## RollingAround (Sep 26, 2011)

I keep it on for the simple fact it can keep a possible slip off chain from going into the spokes causing the rear end to lock and send you into the rocks. I did take it off at first when people said it's a sissy disc and whatnot, but after thinking about it I decided it was a great safety idea and weighs nothing....so I put it back on...might save me a couple of shattered knees possibly.


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## ArmedSuspect (Aug 10, 2012)

after getting a rather large rock stuck between the disk and the gear that little disk pissed me off. i'm not sure how the rock got there but it took a good bit of force to get it out. 

the disk was cut off the next day.





plus, just think of the weight savings!!! :thumbsup:


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