Cassette guard nessecity?

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markemark

Über Member
A cassette guard on a Raleigh ebike has snapped and come off. It was hooked into the spokes.
Is it worth replacing ?
 

fossyant

Ride It Like You Stole It!
Location
South Manchester
Called "dork disks" for a reason
 

Jody

Stubborn git
So long as you're comfortable with skidding at an inopportune moment.

Personally, I don't like or have them on my bikes. But you can still send the mech into the spokes, so be warned.
 
Location
London
I've seen that happen to 3 riders... It can be very costly!

A plastic disc isn't going to help prevent that, so set your rear mech endstops properly.
Might a plastic disk not help at all?
Or at least, with the noise, tell you pronto that something is wrong before it gets worse?

I did once take two spokes out after I bashed an ultegra mech on a park post years ago, but the ultegra mech survived and is still going strong on another bike - damn fine mechs.

My Ridgeback expedition bike (definitely not a BSO) came with one fitted, and having a lot of faith in Ridgeback I decided that they were a good idea - so I bought 2 or 3 from Planet X but gave up on efforts to fit them to some of my other bikes after my feeble brain couldn't figure out how to do it with their spoke patterns.

I can't help but think that they can do little harm, only good - I don't share the contempt for them in some circles that @Cycleops notes.

advice: If anyone's bike ever falls over on the mech side, check things before riding - I once stopped spoke wheel damage on another bike by doing this.
 

Venod

Eh up
Location
Yorkshire
But where does it end ?
A guard on the frame to protect it chance you overshoot the smallest cog.
A guard to stop the chain coming of the front mech at either extremity
Call me old fashioned, but I prefer to set my gears correctly so they don't overshoot.
I always take the discs off if fitted, and never consider fitting one if I build a wheel.
 
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Vantage

Carbon fibre... LMAO!!!
Their purpose in life it to prevent the chain going into the spokes due you folk that don’t have a clue on how to set up the stops on the rear derailleur.

I’ve taken them off all my bikes and never had an issue.

I can't help but feel your answer is particularly rude.
you folk that don’t have a clue on how to set up the stops on the rear derailleur
I suppose you were born with the knowledge to repair your bike?
For the rest of us, we had to learn those skills, many a time through trial and error over time. Some folk are also just not mechanicaly minded.
You folk that can't answer a question without being smug about it should learn to try it.
 

ColinJ

Puzzle game procrastinator!
Might a plastic disk not help at all?
Or at least, with the noise, tell you pronto that something is wrong before it gets worse?
I suppose it depends on how big the protective disk(disc?) is and where the mech makes contact. In all 3 cases I witnessed, the end of the derailleur contacted the spokes in the position 'B' in the example picture below. A plastic plate extending only as far as 'A' wouldn't have helped.

608076


The results in each case were: wrecked mech, broken derailleur hanger***, broken chain, and several broken spokes producing a horribly wobbly wheel.


*** Catastrophic frame damage if the bike in such an incident doesn't have a sacrificial hanger!
 

ColinJ

Puzzle game procrastinator!
Thinking about it more though... :whistle:

The spokes are much nearer to the derailleur at 'A' than at 'B', or at least - they should be. In that case, the disk should/might help. Maybe the derailleurs of the stricken bikes had been bent inwards at point 'B' in the kind of way that you suggested here...

advice: If anyone's bike ever falls over on the mech side, check things before riding - I once stopped spoke wheel damage on another bike by doing this.
 
OP
OP
M

markemark

Über Member
Ok so I understand indexing and the concept of the limiting screws. The gears are nicely indexed so stop properly at the largest cog. How do I know where the limiting screw stops it at as when in first gear I can’t change to below that to know the limiting screw kicks in?
 

ColinJ

Puzzle game procrastinator!
Ok so I understand indexing and the concept of the limiting screws. The gears are nicely indexed so stop properly at the largest cog. How do I know where the limiting screw stops it at as when in first gear I can’t change to below that to know the limiting screw kicks in?
I over-adjust it until I can't select that gear then back it off just enough to allow me to.
 

ColinJ

Puzzle game procrastinator!
Last time I did this was a few years ago but it cost me an XT clutch mech and hanger (plus riding home on a ghetto single speed)
Pretty much as with this rider...

I was in a group of about 30 riders on the Costa Blanca. We had just hit a small hill and were starting to power our way up it when we heard a loud noise and a stream of expletives coming from the back of the group. A rider had just tried to change gear and his gear hanger had broken, sending his rear mech into the wheel. Several spokes were broken, his mech was hanging down into the wheel and the chain was mangled. We were about 30 miles from our hotel, in the middle of nowhere.
We didn't know which had come first... broken hanger or mech in spokes.

It turned out that baggage handlers at the airport had bent his gear hanger***. He bent it back at the hotel, which had probably weakened it.


*** One of my bikes was damaged once too. After this episode I used to unbolt the mech and tape it up inside the frame, to avoid it getting bashed in transit. I think in future I would probably just hire a bike when I got to the resort.
 
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