Superjim2

So there's a plastic ring (disc) behind my rear sprockets that clips on the spokes. I assume it's function is to keep the chain from dropping off behind the largest sprocket between the sprocket and spokes. Looks like a government safety requirement. Do most people leave it on or removed it? Is there a big risk if removed?

SpedFast

Haha. I just did a poll on this. Let me give you the link. It's commonly referred to as the Dork Disk. Up to you if you want to leave it be or not.

https://www.bikeforums.net/general-c...tion-poll.html

PS- Welcome to the forums. Lots of knowledgeable bikers here.

tyrion

Not much of a risk if your rear derailleur is properly adjusted, specifically the limit screw that keeps it from shifting beyond the largest cog.

veganbikes

Remove it, it can really do no good and sometimes actually causes problems. If you maintain your bike and in this case keep your derailleur properly adjusted and check the hanger once and a while or have your shop do so you don't need to worry and if by some chance you crash and your derailleur gets bent that little piece of plastic can't really do much.

If a bike is poorly maintained and the limits aren't set and you do some poor shifting maybe it is a good thing but only in the greater context of a really bad thing that is easily prevented.

Russ Roth

For me, if its there I don't consider it worth the effort to remove and have seen them actually make a difference by protecting the spokes from the chain. However, I also don't consider them worth the effort to get or install when I build my own wheels. So about 1/3 of the bikes in the house have factory wheels with spoke protectors, the rest have custom wheels and no protection.

SurferRosa

The way I see this, it's possible to not be a dork and still feel good about a dork disk on your bike. Not probable, but possible.

maddog34

the main purpose is to protect the spokes if the chain derails into that gap.. the second, and possibly most important, reason they are there is to help prevent the destruction of the derailleur if the derailleur hanger (mount) gets bent badly... and the derailleur, in turn, takes out several Spokes, which can ruin a rim too..

You walk home while carrying the back of your bike........ or walk across a finish line in last place with a ruined race bike, out your entry fee, and looking at a hefty repair bill... A CX race at PIR in Portland caused Several such failures during a particularly muddy race... slip, fall, not notice bent up der. hanger, jump on bike.. clip into one pedal, shift to launch gear, and LOCKUP.... and a long walk of sadness.... i noted 5 bikes in one race, and many more as the day dragged on... puddles were being used to wash grassy mud buildup off the drivetrains.. their Brakes and frames were also packing up tight......the rain stopped in the afternoon... the mud got worse before it got better... The same scenario unfolded at Alpenrose that year...

Dan's bike had a dork disc mounted up.

"sometimes a large dork disc will save your day..." I quipped: "wear it as a badge of experience"

the larger ones will deflect the Der. cages, and you just keep riding........ the smaller ones hide and are not easily noticed... Your expensive Stainless Steel double butted spokes from some distant country will thank you.

I just replaced a munched up derailleur two days ago... the rear wheel was suspiciously different that the front wheel... the dork disc had disintegrated from age on the wheel on the bike... i replaced it too.

urbanknight

I generally remove them the first time I replace the cassette, just because the modern ones are made of a brittle plastic that eventually cracks and makes noise... and is harder to remove when out on the road than one might think.

SJX426 

Only one of my bikes has retained it because it is barely noticeable.
P1000031

nearly all of the others are road bikes that didn't have them when they were acquired by me

One thing to consider, which isn't always significant, is that if they are mounted on the hub and part of the cluster stack, the chain line moves slightly when removed. this is typically on freewheel configurations A spacer fixes that problem , if there is one. The alternative is to adjust the cable length if indexing..

anga

I'd keep it. So little to gain vs so much to lose!

Saved my rear wheel twice, when the chain came off the chainring followed by the rear.
I make it a point to source them for wheels I get built, even though they are not easy to obtain.

Kai Winters

In general it is a very useful device protecting the spokes from damage when the rear derailleur jumps off the gear and gets wedged between the gear and wheel. Most people don't perform any care and maintenance to their bikes. They ride them and that's about it. If it won't shift into the easiest gear they often just continue cranking on the shifter forcing the chain between the gear and wheel...not even the limit screw can save this from happening especially when the bike's der. hanger is usually bent from either being dropped on its drive side or set against the rear der. over and over either bending the hanger or the der. itself.
But just keep on doing it because shops just love replacing chains and derailleurs on these bikes...
Those that regularly perform maintenance on their bikes can do without them because their bikes are kept properly adjusted and most importantly aren't 'force shifted'.
I've always called it either a 'pie plate' or 'spoke protector'.

Superjim2

I just now removed mine. It seems they may provide some function but look like something that belongs on a child's learner bike with training wheels. I would opt for the manufactures to just make a nice metal outer ring or lip on the back of the largest sprocket and works and looks good. But that's $$$

Iride01 

I don't think your conspiracy theory of it being a government requirement holds water. It's certainly not on all bikes. Usually I see them on the low end bikes.

My conspiracy theory on this is that the manufacturer's realize that a majority of people buying low end bikes won't keep them maintained well enough to keep the chain from dropping. And this just helps keep them from getting dinged for not doing something to keep the spokes from getting damaged.

Actually it's more of a conspiracy hypothesis, since none of this is supported by relevant facts or testing.

Oh.... Welcome to BF!

veganbikes

It would actually be less needed on a single speed. Also you don't really learn much with training wheels other than that training wheels are really nice and you won't ever need to balance with them they prevent balancing you can just ride on 3 to 4 wheels.

They really aren't functional because really you just should maintain your bike and make sure your limits are properly set and it is never a problem and since you would want to do that anyway so your bike lasts a long time and works properly it is not outside of normal use and operations.

That metal ring is weight more than money and again really isn't needed with proper care of your bike.

pdlamb

fify

And also, as noted subsequently, the derailer hanger.

smd4

I'm surprised "Big Wheel" hasn't attempted to limit their use. More destroyed wheels = more wheel sales!

maddog34

the "freewheel only" discs actually mount onto a blank step on the hub's diameter... they do not alter the position of the freewheel.

zandoval 

For me the Dork Disk is there to prevent the chain from being lodged between the Freewheel and the spokes. When they do jump the chain skins metal off of one of the most important parts of the spokes. And sometimes you can not get the chain back out without removing the free wheel.

Chain jump on a road bike on the road is rare. And most likely due to loss of adjustment on the rear derailleur.

But six times I have had damage to my spokes and hub components on the bikes I take off the road. And I was not even doing anything like true gravel or heavy single track. I was just driving over a small branch on a bike path or squeezing through some heavy weeds and somehow the chain or derailleur got pushed over. BAMM... Jumped Chain...

Now that I am not really riding on the road anymore, and do not have to suffer the pain and shame of my peers, I keep my Dork Disk's.

Yes... The bikes look so much better without them.

But then again... I look so much better and feel free'er riding without my helmet, but I don't... Hollywood...

Pop N Wood

I once had a brand new chain pop a link when powering up a hill. The loose ends of the chain dropped between the large cog and the spokes, digging deep, while the front wrapped around the front sprocket locking tight.

Walked home carrying the bike that day, road cleats of course.

My rear wheel was almost 40 years old when that chain ate a half dozen spokes. No point in rebuilding with the old hoop, forced me to buy all new spokes and rim.

Have to wonder if the bike still had the dork disc if the rear wheel would still be turning. But like someone else said the dork disc had gotten so brittle it shattered a decade or two earlier.

urbanknight

I would have noticed, but only because it's so close to the fraying cable that would grab my attention. Crimp that thing!

Chuck M 

Welcome to the forums.

And I'm not meaning to put you down, but as you questioned the purpose of the spoke protector and its importance, one can assume you may not have ever experienced adjusting a derailleur. It isn't really that difficult, and the checking of the stop screws is a regular maintenance item IMHO. It would not be a bad idea to make sure the shifting is good in that regard.

Also for what it's worth, I'd probably remove a plastic one too.

Superjim2

Not a put down at all. Actually a pretty good intuition. I have adjusted a different bike a couple times but never felt like I really knew what I was doing but learning my way through it. I'll make a point to get more familiar with adjusting this one. Thanks, everyone.

scott967

Yes, bicycles manufactured for retail sale in the US must have "Derailleur guard. Derailleurs shall be guarded to prevent the drive chain from interfering with or stopping the rotation of the wheel through improper adjustments or damage." Note that that only applies to selling complete bicycles from a manufacturer.

Time was it was a fairly decent looking metal plate, Modern plastic ones I find get crappy-looking quickly. I have a bike with the old Suntour Mountech RD that's a little bent and to get it to shift into the biggest gear I have to adjust it so it can drag a little on the spokes if over-shifted (friction downtube shifters) so I should probably use the pie plate but with multiple wheels haven't bothered and just use normal care when shifting.

scott s.
.

downtube42

Dork disks are dorky, until they become vintage at which time they become cool. To wit, vintage 70's pie plate slotted chrome Schwinn dork disks. Excellent wall decorations or wall clock faces. Your plastic dork disk is unlikely to ever achieve that status. OTOH who knows, maybe unchipped plastic consumer memorabilia will become highly collectable, coming represent the good old days of the 2020's.

Not to say they are not functional.

As stated, a properly adjusted and straight derailleur will put neither itself nor the chain into the spokes. A prideful bike owner who does their own wrenching, or pays big bucks for someone else to maintain their steed, takes the lack of dork disk as a means of distinguishing themselves from the unwashed masses.

I was removing the plastic dork disk on a new bike the other day. Upon removing the cassette, which I assumed was pinned, the sprockets and spacers flung themselves across the garage floor into every hiding place. I found everything except one spacer. The universe was speaking to me, calling me out for my vanity and pride.

SJX426 

That was 10years ago!
Today and as an 8 speed.