You know that clear plastic disc that sits between the cassette and the spokes? Let's say it gets damaged and has to be taken off. Is this something that should be replaced, or is it pretty much optional to have?

I made the mistake of riding a bike with the derailleur out of adjustment, and the chain derailed off the largest sprocket, and tore up that disc. I had to cut out the disc before I could even pull the chain out, it really wedged itself into the plastic. The chain seems fine, and nothing else is damaged.

Optional. The derailluer and right rear dropout have broken before the spokes and wheel did.

It's up to you but after having a chain drop into the gap between the big cassette sprocket and the spokes and take out all the spokes on the drive side I have these guard discs on all my bikes now. Yes folks say that if you set up the limit screws then this won't happen. But it only takes a little pebble or stick or even having the screw move or derrailleur bend slightly to end up with the chain ripping out all or most of the drive side spokes if you don't use one.

So it's your choice. But having one in there is like having fire insurance on your house. You may never need it for your whole life. But if by some chance you need it even only one time it's nice to have.

And if you saw what NOT having one did to my wheel you'd fit one without further discussion.

It's a cheap bike, so I'm still not sure if I'm going to actually replace it or not, on the off-chance that something bad will happen.

But, let's say I do want to get a new one. Are they all a standard size, or will I have to pick one in the right size? And how much do they cost?

They should all fit... but that's actually a good question. I can't seem to find one online... and have no clue what the proper term for it is called. Your LBS should have one, and I wouldn't imagine it costing more than $5.

Either way, if your derailleur is properly adjusted you should never need one. Or just never shift into the bigger cogs (low gears are for wussies).

BC... you have a picture of that wheel? I actually wonder what it looks like to have catastrophic spoke destruction from a rogue chain..

Elitists will tell you that the "dork disc" is not needed, but remember this term was probably invented by a 15 year old back in 1981. These same people will insist that you wear a helmet for safety, but in the same breath tell you that it is absolutely ridiculous to use a spoke protector.

I know how to set derailure stops correctly and STILL, have had derailures get into my spokes - breaking spokes, ruining my tour, destroying the derailure...

I think they serve their purpose. At the same time, I am not sure where to get them anymore.

Let's put it this way, if you have to ask, chances are you don't have the tools to remove the freewheel and replace the spoke protector disc. Your best option is to bring it to a bike shop and have them replace it. If they give you the "you don't need it" speech, say, "Ya, I know.... can you put it on anyway".

+1

To be honest, I kinda like the look of my dork discs. But is that the proper term for them, spoke protectors? I've been spending half the night trying to find one online..

I am not sure where to get them either. I have some spares if "used" is OK. PM me if you need.

Nashbar had some about a year ago. Not sure if they still do.

Further to the purpose of the spoke protector discs, I would much rather hear that scratching sound of the derailure rubbing against the protector disc telling me that things are amiss than the !BOIYOIYOING BOING SNAP CRACKLE POP! of the derailure getting hung up in the spokes.

I wish I had taken one. It was the mechanical equivalent of a really bad road kill.... but without the blood...

All but two or three of the drive side spokes were broken with bent ends. The two or three left were well mangled. The lack of support from the drive side let the wheel collapse and the NDS spokes were maybe 1/4 to 1/3 snapped with the rest mostly just bent into curves with a few being kinked.

The worst thing about it at the time is that it happened when someone was test riding it when I was trying to sell it. He looked real sheepish when he brought it back but I realized it had nothing to do with his actions so after I picked my jaw off the lawn I assured him that I didn't blame him in any way.

Needless to say I lost that sale....

Oddly enough the rim was fine and I rebuilt it with new spokes and the wheel trued up just fine.

Can get 'spoke protectors' at Loose Screws:
https://www.loosescrews.com/index.cgi...d=735102611785

Shimano at Jensen and bikeman:
https://www.jensonusa.com/store/produ...s.aspx?sc=FRGL
https://www.bikemannetwork.com/biking/c/COMPCASSSPROTEC

Pretty easy to find what you need or just go down to your local LBS and they can sell you one. Just be sure you get the right one...some are for freewheel setups...and can come in different diameters depending your largest gear. The old school metal ones are hard to find, but seems to be a desirable item for those that like that look.

Dork discs are for n00bs. And wearing a helmet as well.

https://www.bikeworldusa.com/product_...oducts_id/1436

Sorry but if you've had derailers get into your spokes, you have not set the derailer stops correctly or you had something bent that should have been fixed before it caused damage. Of the 27 bikes I've owned - 18 of them hard ridden mountain bikes where tweeking a derailer is a distinct possibility - I have had very few instances of over shifting into the spokes...all but one, that I can recall, having occurred on a repair stand while adjusting the derailer.

A properly adjusted bicycle in good repair should never shift into the spokes.

They are a throwback to the friction shifting days when shifting too high up the freewheel was a real possibility, serve no purpose on a bike properly indexed.

Even friction shifting derailers had limiting screws. The only reason for the disc is if a the derailer system is incorrectly adjusted. It's CYA and nothing else.

Everything people said about a properly adjusted derailer not getting into the spokes is correct. But... a spoke protector already saved your spokes once. Seems like a simple decision to me.

Very true... very true.... but it's the nature of mechanical stuff to go out of repair. And let's not forget how on a mountain bike an errant twig or other outside addition could force such an overshift despite the best set up limit screws.

It only takes once, trust me. I'm proud to fly my dork discs for any and all to see and ridicule because I KNOW what happens if the cosmos decides to mess up my day.... And it ain't purtty......

I'm not about to risk my derailleurs, spokes, dropouts, and my own hide, just so some unknown person won't make fun of my "dork disc". I have a nice Campy equipped bike that had no spoke protector when I got it, I put one on it.
The local LBS has an assortment of them, probably 8 or 10 different ones. Just take the wheel in and have them put it on. They probably won't charge for installing it, and the disc should be about $5.00.

Expecting something like that to be free is uh yeah.

Rear wheel and cassette needs to come off. Maybe during the off season you could get something like that done for free, or if you're really friendly with the shop.

I have a spoke protector on my commuter, but if it breaks it's not getting replaced. don't ride your bike if it's not shifting well. <-- i'm being a hypocrite. i'm riding my bike to work and running by the LBS afterward to get them to look at why the chain is hitting my front derailleur. do as i say, not as i do.

Wow, dork disks are actually sold as an aftermarket accessory? If your derailleur is adjusted correctly, you'll *never* need one.

The one time it overshifted into the spokes, I knew immediately what had happened and stopped pedaling. The chain brushed the spokes and left no more damage than you'd see from normally stress relieving the spokes during a build. And it was because I had improperly set the limit screws.

The key here...and with any mechanical problem... is to not force anything! Too often I see people thinking they can gorilla a problem into submission. Chain suck? Just pedal harder and it'll clear Shifter not working? Just push harder on it. Tweeked the derailer on a rock? Don't stop and see if everything is still straight just put your head down and keep on pushing! Fix it now or pay way more to fix it later

Haven't used a spoke protector since 1972, when I needed to rebuild the wheels on my Raleigh Super Course.

Caught the derailleur in the spokes once, near the end of a circuit race. Hit the pavement on my left side when the riders on my right started going down, just as I was taking a hit from my water bottle. The finish line followed a hairpin turn and one of the steepest climbs in the race. For all but my last lap I succeeded in reminding myself to avoid using my two lowest cogs. On the final lap I was to far off the back to remember or care. Coasted around the last corner, slammed into a lower gear, and slammed onto the pavement. This time the derailleur jammed itself into the wheel and all I could do was pick up the bike and carry it over the line.

fab one up out of an old LP (vinyl record for you sprouts) or a CD.............be the first on your block!!

If they were not useful the manufacturers would leave them off to save that extra ounce and the expense involved in the part and assembly. Fifty cents and 3 seconds each adds up to real $$$ over a few thousand units.