whats that high teh looking plastic disk begind the cassettes purpose? can i take it of without the world collapsing on itself?

The disk is supposed to keep you from shifting your chain into the spokes. If your rear derailleur is properly adjusted, you can remove it without any harm or danger.


All the cool kids remove them.

Yeah get rid of it. It doesn't even do a good job at its intended purpose, you're better without it.

If you do over shift past the last cog and the chain goes between the cog and the chain it is likely that the chain will damage some of the spokes. if the spokes are cut or notched a little (they will be) you would have to remove the cassette etc. to replace the spokes. It depends on how confident you are about having the derailleur stop screw just right all the time. If the dropout gets bent it can cause the chain to go off too.

Do you know how to check that adjustment if it goes off?

If you know how to fine tune derailleurs, you have our permission to get rid of that offensive looking disk.

Now why didn't I just say that? That's what I meant. !

I've had my chain fall between the cassette and spokes on 2 occasions in the past 5 or so years on a mountain bike. I'm pretty sure a combination of events contributed to this - shifting while on climbing on a technical and bumpy singletrack. Fortunately no major damage. The derailleur limits are properly set.

After that, I decided the spoke protector has value and reinstalled it. I'm the only one in my ride group with one, but as long as I'm the first one up the hill, no one laughs at that unsightly disk.

The plastic disk is not heavy enough to matter but it does have a potential benefit. You might as well leave it on.

Put your bike on your repair stand (for people that think they can get by without one, here is a perfect example of why you DO need one) so that you have access to the drive side of the bike. Shift the RD into the highest gear (i.e. - the little cog). Now, turn the crank with one hand and, with the other hand, push on the bottom/right of the derailleur parallelogram - this will drive the chain to the low gear (the big cog). Keep cranking. If you let the parallelogram go, the chain will shift back to the high gear (because that's where you have the shifter set).

The adjustment you want to make is the "L" limit screw. You want to set the low (= "L") limit screw so that your RD shifts smoothly to the low gear, but not beyond it. When you push on that RD parallelogram you want to push firmly. If the chain jumps off into the spokes or even starts to grind against them, you need to adjust the limit screw accordingly. Look down into the parallelogram and see what the limit screw does and what it stops against.

No need to shift through any of this. Just keep cranking - push the RD so the chain moves up the cogs - adjust the limit screw so you get to the big cog and not beyond.

While you are at it you might as well adjust the "H" limit as well. When you let the chain come back down to the small cog it should only get to the small cog and not beyond. When you are done with the limit adjustments keep cranking and shift through all the gear combinations and fine tune if necessary.

You can do these adjustments with the shift cable disconnected if you want. Cable tensioning for index shifting and "B" adjustment are another issue.

There are a few people in the universe clever enough to do it without one, and have never shifted off the big cog either.

And, to those clever enough, I tip my hat

The coolest spoke protector I've ever seen was an old Jerry Lee Lewis 45. Hey, it works and it is different.

Doc

Only those who have overshifted (for one reason or another) past the big cog and wiped out 9 spokes in one pedal stroke know the meaning of "plastic disc".

I just cut mine off recently...because I am a slave to conformity and couldn't bear to be the only guy riding with one.

Seriously though, my D's are adjusted properly and I haven't had an issue yet. Plus, if I do end up destroying my spokes I have an excuse to upgrade my wheelset.

PJ

a small whack mid-ride is enough to knock your D's out of place. You may not notice until it is too late.

few people? all you have to do is flip your bike onto the seat and handlebars and tada you can now tune your derailluers. I recently took my "plastic disc" off because it broke at the clips that it hugs the spokes with and was not letting the cassette float easily. but damn that thing was really hard to get off

Huh? Wet where you ride?

I've dropped the chain into "The Void" as I call it, with no damage. It is about being connected to your bike, knowing when a problem might happen before it becomes one. Regular maintainance helps too.

All you have to do is ease up on the pedaling when you shift. Less wear on chain/cogs, no grinding noises, significantly reduced possibility of overshifting damage. I've overshifted a few times but haven't caused any damage because I pedal gently during shifts, and was able to stop the cranks immediately.

You took the cassette/freewheel off and looked at the nine spokes right where they hook into the hub?

Sorry, but also, how does regular maintenance help if the stop screw is set correctly in the first instance?

Just trying to learn something here so I don't repeat my episode...

I like it! Any idea how to attach it to the wheel so it spins with the wheel? I'd like something a bit cooler than duct tape. Perhaps drill a hole thru the record and fabricate a clip of some sort?

Now I gotta hit a vinyl record store.

What kind of man are you? Zip tie!

I say leave it on. When i'm shifting upwards i usually 'over-shift' to get the chain on the top chainring, i push the leaver further then usuall which moves the derailer past the chain ring so the chain can slide onto it quickly. If i didn't have the plastic disks the chain would slip right past the chain ring and onto the spokes. Like people have said, there is no weight difference and it's just clear plastic so why bother?

Doesn't happen with a properly adjusted derailieur. The "dork disc" correctly identifies you (in general) as a novice

edited because someone takes themself way too seriously for their own good

ok, just for you I will edit what i was trying to say. I was ment to be talking about the front chain-ring set, and when i'm trying to ****f upwards , i sometimes over shift. Especially when going up hill, or when your not pedaling fast enough, it takes longer to shift, so i will over shift. And without that plastic disk my chain would probably come off.