Bicycle Mechanics - what the plastic disk for?

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.

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. ! :o

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

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.

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


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.

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

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

my D's are adjusted properly and I haven't had an issue yet.

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.

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

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

...and was not letting the cassette float easily.
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.

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.
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...

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

Doc


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.

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?

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

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

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.

Even I have to say: Huh?

It's just Raiyn; he gets all tangential so early in the morning if he doesn't get his hot cuppa! ;)

No, no, Raiyn's fine. I'd never argue, question or swear about him behind his back.

But, I think blue neon is confused. I think he's talking about the guard fitted to chainrings on the front and the chain overshifting past the big ring. I might be wrong. But as I said about his last two posts: "Huh?"

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.Hot glue gun???

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

You will have a excuse to upgrade your dental set also if things turn out nasty on a long down hill run at 40 mph.

Funny how many in here have no concept of random failures, defective manufacture and so on...
A "bad things never happen to good people" or "it will never happen to me" attitude.
If I just keep my gear in best working order, nothing will ever break.

Oh man...

Funny how many in here have no concept of random failures, defective manufacture and so on...
A "bad things never happen to good people" or "it will never happen to me" attitude.
If I just keep my gear in best working order, nothing will ever break.

Oh man...

Since I've been riding as a kid off and on (probably 15 years worth of riding - obviously not 24/7 during those times), I have never shifted into my wheel. I even ran a rear wheel laced with carbon fiber spokes without "the disk". I did eventually change out the carbon spokes becuase I broke them due to riding hard (I suppose).

Will it never happen to me? Doubt it, but I'm taking the chance, I guess.

I did run my chain through no mans land once on my MTB. Everything was adjusted perfecly...........except that stump. Mangled the der, and the chain did damage the spokes right where they go into the hub.

I still won't use a dork disk. I'll take my once in eight year hit.

If one removes the so called "dork disk" for aesthetic reasons, doesn't that also suggest tassles should be removed from the bar ends?

Leave the disk where it is. Why go to the trouble to remove it? Let it sit there for years and do nothing but draw the derision of the serious cyclists. Yet it might someday prevent a serious crash caused by a chain that wraps itself around you wheel hub after it has removed half your spokes. Of course some of the serious cyclists are correct in saying that having the disk in place, causes the serious cyclists to view you as a novice. I like to think of the dork disc riders as those not looking to others to see themselves clearly. They get their selfimage from inside.

Something like that actually happened to me many years ago.
(I was probably 10 or 11 at the time, so I wasn't exactly into maintenance...)
I was riding along when I suddenly stopped dead and fell.
The rear derailer had snapped and bent straight into the wheel.
Luckily, I was only doing maybe 5-6 km/h at the time, so I didn't get hurt, but if I'd been doing 20-30 km/h, I would've been badly hurt.

That said, I don't have a disk at the moment, but I'll probably get one for next year.

I guess peer pressure is alive and well. God forbid that somebody should think of you as a novice. How on earth are you going to live with yourself. ;)

I have one of those disks and guess what, it stays (low normal set up and all). Not because I am particularly worried about breaking my spokes, but because I don't ride to impress others.

I have lost both dork disks on my bikes. Not because i wanted to but because they both broke off. One broke off, several miles from home and made for a very long ride. It didn't come clear off, it just sat there and spun, snagging my freehub. That sucked, cuz i had nothing to cut it off with.

"And when he does his little rounds
Round the boutiques of London town
Eagerly pursuing all the latest fancy trends
Cos he's a dedicated follower of fashion"
The Kinks

Can't have all the cool kids looking down their noese's at me :p

Pfft let people think you're a novice, then drop them like a calculus course. Of course if you really are a novice... what does it matter that they think you are one..?

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?

this is why derailluers have limit screws. adjust it properly and put on some loctite and this wont happen.

and this wont happen.

Again, what can I say... :rolleyes:

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

And dork wheel reflectors... Nothing says "novice" more than safety equipment!

adjust it properly and put on some loctite and this wont happen.
Put on some loctite and adjust it properly?

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.
Not like you can read this anymore, but the "dork disk" is the plastic piece inbetween the cluster and the spokes of the rear wheel. I wasn't even the one who coined the phrase http://www.bikeforums.net/search.php?searchid=607528 hence the quotation marks. The thing referred to in the quoted post is called a chain guard and is attached to the crank / chainrings. One more thing your front derailieurs out of adjustment. If it was done right you wouldn't have to worry about the chain coming off.

this is why derailluers have limit screws. adjust it properly and put on some loctite and this wont happen.This is why your LBS LOVES you. :rolleyes:

And dork wheel reflectors... Nothing says "novice" more than safety equipment!When strips of reflective tape on the rim between the spokes do a much better job and are lighter why not take the heavy plastic crap off?

if you're dork disc broke off does that still count as "succumbing to peer pressure"?

Feel free to leave it on but if it breaks into pieces while you're riding, you are obligated to pick them all up. I've seen so many reflectors and spoke protectors littering the trail. I personally think they're useless. And in actuality, I do have one on my roadbike. It's very small though and really only useful if I had a 23 as my biggest cog. However, it's unseen and hard to remove so I just leave it on there.

http://www.neebu.net/~khuon/albums/2001-aegis-aro_svelte/PICT0017.jpg

For my other bikes, I snip them off rather than haul them around as potential trail-litter.

http://www.neebu.net/~khuon/albums/1999-k2-ozm/PICT0013.jpg

Feel free to leave it on but if it breaks into pieces while you're riding, you are obligated to pick them all up. I've seen so many reflectors and spoke protectors littering the trail. I personally think they're useless.

]
I agree completely

Of course, if you really want to go the full hog on a dork disc, take a look at certain time trial bikes with their disc wheels covers -- the ultimate spoke protector, and you go faster, too!

My DH rig never had one, and when I was doing some jumps, about 20-30km/h when hitting, I had to move in the air so as to not kill a little kid. To cut a long story short, I had my derailleur hook up into my spokes (I landed sideways) this ripped my derailleur out of the hanger and went full circle in my wheel. All that happened was my rear locked up so I rode it out. And all that needed to be replaced was a chain, derailleur, hanger and 5 spokes. Even if I had a dork disc it wouldn't have saved my wheel as the cage got caught in the spokes.

The reason, I think, the derailleur went in the wheel was that I may have had a slightly bent hanger from earlier in the day and the force of landing sideways at speed. An in the morning my derailleur was set up nicely.