Plastic spoke protector behind cassette, DO I NEED IT?
06-03-17, 07:17 AM
#1
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Plastic spoke protector behind cassette, DO I NEED IT?
Is the protector needed? Mine broke and thru me down on road. I had messed up the front shifter and was working my way home when going up a hill I shifted on the highest cog and the chain caught on the protector and on spoke which stopped me real fast. I was going slow so damage was minimal. Took bike to LBS and they repaired the bike and it works good now but they did not replace the protector. Called the LBS and was told that I did not need it.
IS IT NEEDED????
IS IT NEEDED????
06-03-17, 07:28 AM
#2
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It prevented your chain from going into your spokes which would have been a bigger problem. If your limit screw is set properly, then you don't need it. If not, it's an insurance policy.
06-03-17, 07:28 AM
#3
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It isn't "needed"...so long as you have properly set limit screws on the rear mech.
06-03-17, 07:51 AM
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if you take it off you void your bike's warranty .. plus, taking it off breaks several federal laws ... it is like the tag on your mattress and pillows.
06-03-17, 07:54 AM
#6
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Removing it only breaks laws if you're a retailer, or an employee working for one, modifying merchandise. AFAIK there are no federal laws (and no state laws at least in Nebraska) requiring riders on the street to have them.
06-03-17, 08:41 AM
#7
Farmer tan
Based on what happened in the original post, the guy doesn't know how to tell if the upper limit screw is properly adjusted.
There are 2 limit screws on the rear derailleur, labelled H and L.
One prevents the derailleur from moving too far towards the wheel whenever you shift into the largest cog in the back (lowest gear). If it's adjusted to allow too much movement, the derailleur will hit the spokes. If it's adjusted to allow insufficient movement, the chain won't go onto the largest cog.
Sometimes it may look like the limit screw is correctly adjusted, but actually the cable tension is the only thing preventing the derailleur from hitting the spokes. You can only tell by removing all tension in the cable and setting the limit screw first. Then re-tensioning the cable for correct shifting.
So, yes, a spoke protector is needed, unless you learn how to check this.
There are 2 limit screws on the rear derailleur, labelled H and L.
One prevents the derailleur from moving too far towards the wheel whenever you shift into the largest cog in the back (lowest gear). If it's adjusted to allow too much movement, the derailleur will hit the spokes. If it's adjusted to allow insufficient movement, the chain won't go onto the largest cog.
Sometimes it may look like the limit screw is correctly adjusted, but actually the cable tension is the only thing preventing the derailleur from hitting the spokes. You can only tell by removing all tension in the cable and setting the limit screw first. Then re-tensioning the cable for correct shifting.
So, yes, a spoke protector is needed, unless you learn how to check this.
06-03-17, 09:01 AM
#8
Banned
In a Perfect world... I have one on my touring bike , because its not going to be perfect.
And Trashing your rear shifter and wheel in the boonies can strand you helplessly.
tipping over the bike to the right side and bumping the RD out of alignment
is all it takes to screw up the shifting adjustments, , and have that damage cascade.
....
And Trashing your rear shifter and wheel in the boonies can strand you helplessly.
tipping over the bike to the right side and bumping the RD out of alignment
is all it takes to screw up the shifting adjustments, , and have that damage cascade.
....
Last edited by fietsbob; 06-03-17 at 09:10 AM.
06-03-17, 11:31 AM
#10
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It's called a "Dork Disk" and if your RD limit screw is set properly, you don't need it.
That said, if your bike falls over and your RD hanger gets ever so slightly bent, it could save your sorry ass from shifting the chain into the spokes.
I hope that helps.
That said, if your bike falls over and your RD hanger gets ever so slightly bent, it could save your sorry ass from shifting the chain into the spokes.
I hope that helps.
06-03-17, 12:03 PM
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Right. It's not just "set the limit screw". It's:
Set the limit screw
AND
Check your derailleur hanger alignment
AND
Make sure your rear QR/through-axle is tight and properly positioned
AND
Ensure your rear derailleur is free from damage
Before each ride.
Since most folks won't do any of these, the dork disc sits there as insurance.
Set the limit screw
AND
Check your derailleur hanger alignment
AND
Make sure your rear QR/through-axle is tight and properly positioned
AND
Ensure your rear derailleur is free from damage
Before each ride.
Since most folks won't do any of these, the dork disc sits there as insurance.
06-03-17, 12:38 PM
#12
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If you have to ask you need it.
If you don't know how to remove it yourself non destructively, you need it.
If you don't know how to remove it yourself non destructively, you need it.
06-03-17, 12:39 PM
#13
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And OP it didn't cause your fall. If anything it limited the damage
06-03-17, 12:57 PM
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My kid has 3 Dura-Ace Di2 bikes (top-end electronic). In the last 4 years we've used the same cassette and hubs on the back.
Two months ago for the first time because he is no longer a junior, he put a Dura-Ace cassette on. It sits a wee bit farther out from the spoke.
Nobody - me included thought anything of it.
He shifted the chain in.
The ruined some spokes on a very nice race wheel. That made for some crazy running around before an important race and racing on some spare spokes at nationals.
Not that he would have had that disc on anyway, but mistakes happen. They of course happen less when paying attention.
Two months ago for the first time because he is no longer a junior, he put a Dura-Ace cassette on. It sits a wee bit farther out from the spoke.
Nobody - me included thought anything of it.
He shifted the chain in.
The ruined some spokes on a very nice race wheel. That made for some crazy running around before an important race and racing on some spare spokes at nationals.
Not that he would have had that disc on anyway, but mistakes happen. They of course happen less when paying attention.
06-03-17, 03:06 PM
#16
Senior Member
06-03-17, 07:41 PM
#20
Erik the Inveigler
You don't need it (as long as your derailleurs are adjusted properly). But, if your bike is vintage and came with a pie plate you hate to take it off. I did, when fixing up this old bike and when I switched to a new freewheel I found that I no longer had room to reinstall it. Bummer.
Last edited by Scarbo; 06-03-17 at 07:45 PM.
06-03-17, 08:03 PM
#21
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Plus , depending on gearing, derailleur and chain stay length, it's possible to drop a chain on the inside, even with a well adjusted setup.
A guard to avoid dropping a chain on the inside is light, not unsightly, functional, and guards against an issue not avoidable in som instances by just setting the limit screws correctly.
Dork disc meets none of those criteria
06-04-17, 12:26 AM
#22
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One works; one doesn't
Plus , depending on gearing, derailleur and chain stay length, it's possible to drop a chain on the inside, even with a well adjusted setup.
A guard to avoid dropping a chain on the inside is light, not unsightly, functional, and guards against an issue not avoidable in som instances by just setting the limit screws correctly.
Dork disc meets none of those criteria
Plus , depending on gearing, derailleur and chain stay length, it's possible to drop a chain on the inside, even with a well adjusted setup.
A guard to avoid dropping a chain on the inside is light, not unsightly, functional, and guards against an issue not avoidable in som instances by just setting the limit screws correctly.
Dork disc meets none of those criteria
06-06-17, 10:04 AM
#23
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Additionally if the chain comes off the inside, it can jam between the cog and the dork disc about as easily as it jams between the spokes and the cog. Neither one of these things is good.
So a simple, light, unobtrusive chain retainer on the front, works, and prevents dropping the chain on the inside of the small chainring, preventing scratching your frame.
Dork disc offers little to no actual protection, and can cause its own problems jamming the chain between the disc and the cog.
At worst the dork disc gives a false sense of protection.
__________________
You could fall off a cliff and die.
You could get lost and die.
You could hit a tree and die.
OR YOU COULD STAY HOME AND FALL OFF THE COUCH AND DIE.
You could fall off a cliff and die.
You could get lost and die.
You could hit a tree and die.
OR YOU COULD STAY HOME AND FALL OFF THE COUCH AND DIE.
06-06-17, 11:58 AM
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The problem is the derailleur being misadjusted going off the inside of the largest cog. If your rear derailleur is misadjusted to that point, its likely the rear derailleur cage is going into the spokes when you shift like that, which is way more catastrophic than just the chain into the spokes, and the dork disc won't prevent that.
Additionally if the chain comes off the inside, it can jam between the cog and the dork disc about as easily as it jams between the spokes and the cog. Neither one of these things is good.
So a simple, light, unobtrusive chain retainer on the front, works, and prevents dropping the chain on the inside of the small chainring, preventing scratching your frame.
Dork disc offers little to no actual protection, and can cause its own problems jamming the chain between the disc and the cog.
At worst the dork disc gives a false sense of protection.
Additionally if the chain comes off the inside, it can jam between the cog and the dork disc about as easily as it jams between the spokes and the cog. Neither one of these things is good.
So a simple, light, unobtrusive chain retainer on the front, works, and prevents dropping the chain on the inside of the small chainring, preventing scratching your frame.
Dork disc offers little to no actual protection, and can cause its own problems jamming the chain between the disc and the cog.
At worst the dork disc gives a false sense of protection.
06-06-17, 12:02 PM
#25
Senior Member
You're supposed to remove it with fire.
