Bicycles Stack Exchange
Bicycles Stack Exchange

Questions tagged [derailleur]

Mechanism to move the chain from one sprocket to another.

A bicycle mechanism that moves the chain out and up, allowing it to shift to different cogs. There are two classifications of derailleur: front and rear.

The front derailleur is used to adjust, in large jumps, your pedal cadence from very easy to very hard.

The rear derailleur adjusts your pedal cadence in smaller jumps.

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Why are derailleur jockey wheels commonly made of nylon?

Almost all derailleurs seem to come from the factory with nylon jockey wheels . What is the rationale for the use of nylon (rather than alloy or aluminum)? Is it merely weight savings (which would seem to be trivial given the size) or is there a…
RoboKaren
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Selecting a front derailleur: parameters

The spec sheet for the Shimano Alivio FD-M430 front derailleur contains a number of points that I don't understand. What does "Maximum capacity: 22 teeth" mean? Why are "Top gear teeth" constrained to "44/48T"? Is there anything wrong with 46? What…
Vorac
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How do I locate and loosen the rear derailleur hanger bolt?

Context: I need to remove my rear derailleur so that I can attach an alignment tool and straighten things out. Images of the rear derailleur while the bike is…
Zian Choy
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Why is there a distinction between friction and indexed derailleurs?

I've seen people make a distinction between a derailleur being for friction or indexed. Is this distinction somehow functional? I can't see how it could be, because every derailleur I've ever seen just takes a movement in the cable and translates it…
Darth Egregious
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Practical benefits of expensive jockey wheels?

Today I had to make a detour to the bike shop as a jockey wheel decided to fly out of a friend's derailleur. The shop were able to supply a replacement retaining bolt free of charge, however the only jockey wheels that they stocked were cartridge…
ʍǝɥʇɐɯ
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Can't push lever to shift into big ring, lever will not move all the way

I just installed a new 6800 groupset on my bike for the first time, and everything went O.K except for the front derailleur. I can't shift it into the big ring, if I push the lever to change to the big ring, it won't go all the way, and it won't…
suskie
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XTR Shadow Plus derailleur soft setting?

XTR Shadow Plus derailleur has a switch between a hard and soft chain tension. The difference is hardly noticeable when shifting. Is there ever any good reason to use the soft setting when the hard setting keeps the chain quite more stable on…
HoursFrom.World
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The bike derailer will automatically drop to the lowest gear in the rear whenever my cadence slows

I have a REI Coop CTY 2.2 bicycle. Whenever I am biking and my cadence slows down, the bicycle derailer automatically (I am not shifting) to the lowest gear on the rear derailer. Any suggestions on how to fix other than not to get tired? The…
Meg
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Is there any functional point of using alloy jockey wheels?

Jockey wheels seem like the most pointless thing to upgrade on a bike. I can see swapping out the usual grey ceramic jockey wheels for an anodized alloy one to match the look of the rest of the bike, but I can't see any possible performance related…
Darth Egregious
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is this derailleur short cage or long cage?

I'm selling the rear derailleur off this bike, and someone asked whether it's short or long cage. I assume it's long. Is this correct?
jela
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Are there mechanical advantages and disadvantages of various front derailleur styles?

In general there are: High clamp Low clamp Braze on Top pull Bottom pull And in particular, is any of those better choice regarding reliability and durability for touring bicycle.
Davorin Ruševljan
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What's going on with the bonkers derailleur?

My friend changed her tyre with the bike upside-down, struggling to slot in the axle and the derailleur just fell off from pressure with her bare hands. She is far away so I need to understand what tools to take before I go there. There's a weird…
bandybabboon
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What is this retainer ring?

Shimano RD-9000 which is a bit dinged up due to me setting the bike down...with my feet still clipped in to the pedals What does this ring do, can/should I snap it back in to place, and how? I have already tried a hex key down the barrel and it…
user47434
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Installing a chainguard on a bike with derauiller

My pants always get caught in the chain (and wearing shorts is not an option). However, it seems that it's impossible to have both a derailleur and a chainguard so what is the solution? Can I just lock the front derailleur in place and slip the…
SurpriseDog
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How do I select a rear deraileur for my mountain bike?

I have damaged my rear derailer and are looking for a replacement, aside from replacing it with the exact same model, what do I look for in terms of compatibility. I note that there are long medium and short cage sizes, what is the difference? Also,…
JeffV
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