Bit of plastic behind the cassette?

SamN01

Well-Known Member
Location
Cambridge
I bought some new wheels and a cassette. My current wheel has a plastic disk behind the cassette. What is it for and do I need it? Do I need to buy one for the new wheels? Stupid question from a newbie I know but any answers appreciated.
 
The plastic disc is there to stop a poorly adjusted mech shifting down past 1st gear and throwing the chain into the wheel. With a properly adjusted mech this will never happen so you don't really need it and a lot of folk tend to remove it.
 

crankyhorse

New Member
If the chain does go in to the wheel it can damage the bike and send you flying.

I had that happen years back and I will not buy a bike without one. Especially since my next bike will be a C2W from Halfords :blush:
 
I had that happen years back and I will not buy a bike without one. Especially since my next bike will be a C2W from Halfords :blush:
I bought a new bike recently and the first thing I did to to it was to remove the plastic disc by attacking it with a pair of sidecutters. I know why it's there, but I make sure that the rear mech is properly adjusted so that it doesn't shift into the spokes. I don't wish to be condescending, but I regard a plastic disc (on a decent bike) as something as a 'badge of shame'.
 
OP
SamN01

SamN01

Well-Known Member
Location
Cambridge
The reason I asked is that I am also swapping the 105 11/25 cassette for a ultegra 11/25 cassette myself, is the rear mech likely to need any adjustment?
 
The one that came on my bike can stay on my bike. It's hurthing nothing. I have enough to do without removing the cassette to get the disc off, and like my bike too much to deal with things by smashing them off
 

Gixxerman

Veteran
Location
Market Rasen
The bike snobs would call it a "pie plate" and ridicule you for still having it on your bike, and treat you like a social outcast and probably refer to you as a dork.
I personally can't see anything wrong with it and it does perform a valid function (albeit a mostly redundant one for correctly setup bikes).
I still have mine attached and couldn't care less what people think about it.
 

Rip Van

Veteran
Location
Rothes
The bike snobs would call it a "pie plate" and ridicule you for still having it on your bike, and treat you like a social outcast and probably refer to you as a dork.
I personally can't see anything wrong with it and it does perform a valid function (albeit a mostly redundant one for correctly setup bikes).
I still have mine attached and couldn't care less what people think about it.
+1
 

Captain

New Member
I have it on mine because I don't see the point in taking it off.
hell I could even paint it a funky colour to make it cool.

Why do people take it off when it could save you a fall, chain, some paint etc..?
 
Why do people take it off when it could save you a fall, chain, some paint etc..?
The last time I overshifted a chain into the spokes because of a poorly adjusted rear mech was about forty + years ago, so if I don't see a need for it - it need not be there. On a similar note I have three bikes; two of them do not have mudguards. I acknowledge that they can serve a really useful purpose, but if I do not intend to ride that bike in the wet, what need is there for them?
 

MJN

New Member
Location
Bristol
You are putting an identical cassette (just one which is a little lighter); if you never experienced the chain going into the wheel before you will not require new adjustment.
Wise words! :smile:

To Sam, it will definitely be worth you checking and adjusting if required as a matter of course just in case there is a difference in theory and practice. Furthermore, given how straightforward it is to do there's little reason not to.

If you're unsure how to do it then I can appreciate that it may seem like a daunting task, however there are plenty of guides around, not to mention plenty of willing people on here!, to help you to do it.

Mathew
 
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