that thing, what's it called? y'know, the doohickey...

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  • that thing, what's it called? y'know, the doohickey...
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Anonymous's picture

Spoke Protector?

Wussy Wheel?

Medial Cassette Infrastructure Obstructificator?

I'm talking about that thin clear plastic disc that sits in between the largest cog on my cassette & the spokes of the rear wheel, on my 10-year-old Trek 750 hybrid.

Or rather, that *sat* there...until yesterday when I was riding & started to hear a weird clicking. Turned out that whatever cheesey mounting method previously held this widget centered between my hub & cassette no longer existed, & the doohickey was now flopping around loose. After I got home I examined it as closely as I could without disassembling my hub, and eventually concluded that some plastic protrusions had snapped off. IOW, this device could not be repaired, it would have to be replaced. So I removed it & threw it away.

Now, I know a lot of bikes don't even have these gizmos, so I'm pretty certain it's not required. Then again, those bikes I've seen without this thing never had one to begin with, so maybe I'm completely wrong.

- What purpose was this disc supposed to have performed? (Protect my spokes from overzealous downshifting, perhaps? Keep debris out of the back of my cassette?)
- Am I correct that, even though my bike came with it, I don't really need it?
- Is there any chance that, having removed this light (<10g) flimsy piece of plastic from the right side of my wheel, I now need to get my wheel re-trued or re-balanced?

Thanks for any help.

Anonymous's picture
Too much time on my hands (not verified)

"If I had to give it a name, I would call it ""the useless piece of plastic that marks its owner as a newbie.""

About as necessary as t*ts on a bull. The only thing that's more ridiculous are ""lawyer tabs."" (If you don't know how what a lawyer tab is, wait five minutes, and hopefully, lively debate will ensure.)

Your bike was trying to give you a hint. Both you and your bike will be glad it's gone now. No, you do not need to perform any post-plastic removal maintenance."

Anonymous's picture
Rick (not verified)
suggestions for removal?!!

I need that thing off! any suggestions on a safe removal from someone who's done it before or should I bring to shop for them to remove?

and, what is the purpose for it? thx

Anonymous's picture
Popeye Doyle (not verified)

Ginzu knife. Saw right through that mofo and pull it off.

Anonymous's picture
Ted (not verified)

The purpose is to keep your wheel and rear derailleur from being destroyed if the derailleur gets sucked into the spokes for some reason. Some reason usually being poor adjustment, or a stick or rock bending the derailleur in.
On a road bike, they are not much use, but I have seen a couple of mountain bikes with some major damage. The derailleur gets snapped around and broken, but usually takes out a few spokes first.

Anonymous's picture
Too much time on my hands (not verified)

This is where you learn to remove and install a cassette. Super easy. Campy or Shimano compatible locknut, chain whip and wrench are all that's needed.

Anonymous's picture
Rick (not verified)

Thanks guys. Seems like a wasted accessory for a road bike. Has anybody ever had the rear derailer kick up into their wheel?

Anonymous's picture
Mordecai Silver (not verified)
Spoke protector
Anonymous's picture
Rich (not verified)
Spoke protectors on high end bikes & wheels

You shouldn't need it if:
1. Your rear derailleur is adjusted properly so that it can't shift beyond the innermost/low gear.
2. You have reasonably decent shifting technique so that the chain doesn't get at such a sharp angle to the lowest gear that it can roll off into the spokes (like trying to shift all the gears at once, high to low, while doing a standing start).

While some may see it as the mark of a somewhat low-end bike or rank-newbie, this spring I've seen a lot of high end wheels (and of course, I can't remember which brand--maybe Shimano?) with a huge black spoke protector behind the cog.

To safely remove it, it's best to remove the cassette using a lockring tool & a chainwhip.

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