Questions tagged [derailleur]

Mechanism to move the chain from one sprocket to another.

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25
votes
6answers
169k views

How to calculate the capacity of a rear derailleur

It's easy to calculate what capacity of a rear derailleur will be needed based on the size of the big and small chainring and the big and small cog. What about the converse question, how to calculate ...
11
votes
2answers
20k views

Moving tfrom Shimano 9- to Shimano 10- speed

I'm thinking of changing the 9-speed Tiagra rear mech on one of my (road) bikes to something, still Shimano, but 10-speed. The obvious replacements I'll need are cassette, right-shifter and chain. ...
9
votes
3answers
16k views

Road Shifters, Mountain Rear Derailleur?

I have a road/cyclocross/commuter frame that is currently spec'd with road components - all Shimano 105, with an Ultegra rear derailleur. The cassette (10 spd) tops out at 27 teeth, and the rear ...
11
votes
3answers
35k views

How do I adjust my rear derailleur (Shimano SIS) when it is only slightly out?

It has been a while since I had my bike serviced and the gears are sometimes slightly out of perfect alignment. This results in the occasional mis-shift. I also think the change in seasons have ...
45
votes
11answers
35k views

What's the efficiency of hub gears compared to derailleurs?

What's the efficiency of hub gears compared to derailleurs? I know that hub gears are not as efficient. Apart from being heavier, how much will I lose in performance if I use hub gears?
4
votes
3answers
60k views

Determining which derailleur hanger is compatible with a frame

When your derailleur hanger needs replacing, is there a good resource for matching frames to hangers? Mine was recently bent, so I had to dig through some websites and compare pictures of the hangers ...
10
votes
3answers
56k views

Is my chain too long?

I'm in the process of setting up a new drive train. When using the smaller chainring and smallest sprocket (hence least amount of utilized chain), the chain brushes up against the bottom of the ...
15
votes
3answers
63k views

How can you identify if a Shimano rear derailleur is medium or long cage?

I have a 2013 Shimano XT rear derailleur. It is part of a 2x10 drivetrain. How can I find out if it is a medium or a long cage one? The picture below shows the derailleur.
5
votes
2answers
3k views

(Automatic Bike Project) amount of torque required to change gears?

I am planning to build an electronically controlled automatic bike transmission for my senior design project. I'm personally more of an electrical guy, so dealing with the mechanics is somewhat new to ...
13
votes
2answers
1k views

Bike chain slips in a strange way

I bought a new bike about a month ago. And it made a strange sound from the first ride , I thought the sound was because it was new and will disappear with time but it didn't. The sound is like a ...
6
votes
3answers
9k views

Does a rear derailleur guard provide effective protection?

I recently caught my rear derailleur on a log and snapped it in two. I have done some recent work on some department store bikes and noticed that some come equipped with an axle mounted guard around ...
36
votes
5answers
12k views

Perfectly setting up gears - how?

Every time I have my bike serviced, the bike shop sets up the gears on a stand in their workshop. The gears change perfectly on the stand, but when the bike is on the road, the rear derailleur doesn't ...
9
votes
7answers
74k views

Problem with chain skipping without trying to shift (even with new chain and gears)

I have a mountain bike where the chain intermittently skips when put under load on the middle (and very rarely on the smallest) chain ring. It is not related to shifting. I've taken several steps to ...
16
votes
2answers
44k views

Chain slipping off derailleur jockey

Last week, I had to abandon a training ride due to my chain slipping off my rear derailleur jockey wheel. This would only happen when shifting, and most often when either shifting chainrings or ...
15
votes
6answers
67k views

Bike is shifting on its own

Ever since I got my bike (Surly Long Haul Trucker), it has been prone to shifting on its own. This is almost guaranteed to happen when I stand up on the pedals, and happens regularly when sitting as ...
6
votes
3answers
2k views

What are the most common causes for hysteresis in the rear derailler?

I have often seen derailleurs on cheap MTBs to degrade in performance by showing hysteresis. By that I mean that to switch to a certain cog, one needs to shift one cog further and then immediately one ...
13
votes
1answer
8k views

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 ...
6
votes
2answers
2k views

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?
3
votes
3answers
374 views

Gear shift adjustments

I recently had to replace the shifters on my bike. The replacement was easy enough, but now when I shift the derailleur either jumps too far or too short. I've tried using the adjustment screws on the ...
1
vote
3answers
7k views

Can't shift to gear one or two

I had an issue where every time I put my bike in gear 3, it would just keep "skipping". By this I mean that it wouldn't stay in gear 3; the chain would go onto it, then fall onto gear 4, then go back ...
9
votes
7answers
63k views

Can a road bike's rear derailleur be used for either a 9 speed cassette or 10 speed cassette?

I currently have a 9 speed 11-25T cassette on my road bike. I'm thinking about switching to a different cassette with more teeth on the climbing gear. The cassette I'm currently look at is a Shimano ...
8
votes
4answers
35k views

Can I fit a cassette with a larger range with my Shimano Tiagra 10-speed ( GS-4600) derailleur?

I'm currently running a 2x10 shimano tiagra 10-speed drivetrain with a 50/34 compact crankset, a 12-30 rear cassette, and a Shimano Tiagra GS-4600 derailleur (that's medium cage aka road long cage) on ...
7
votes
4answers
16k views

Are the Shimano derailleurs sold on Ali Express genuine or fake?

I am trying to buy Shimano Alivio M4000 components. When I was researching on Ali Express, I found this. This is Alivio M4000 including the front derailleur, rear derailleur, left and right Shifters ...
4
votes
1answer
6k views

Replaced Shimano Bottom Bracket, now front derailleur won't shift to largest gear

OK, so in my quest to get my old Trek 7000 ZX MTB running again after a long retirement, I am having an issue with replacing the bottom bracket. The bike came with a Shimano LP25 that is marked BC 1....
3
votes
1answer
5k views

Converting a short cage rear derailleur to a long cage derailleur

Is it possible to convert a short cage rear derailleur (for example the Huret Svelto) to a long cage derailleur by just taking the lower cage and replacing it by a longer one?
2
votes
1answer
142 views

Shimano RD-R7000 cable cut into thread?

That gap/cut in the hollow screw of the cable mount is not supposed to be there, right? If so, is this a typical defect? The hollow screw is pressed into the derailleur body and not replaceable, so ...
2
votes
3answers
344 views

Why does my front derailleur not work when it is cold?

When it is warm outside my front derailleur works just fine. But when it gets colder (40F) the lever on the handle bar does not catch and I can move it without any resistance the whole way without the ...
2
votes
2answers
3k views

Road Front Derailleur / Shifter Tuning

I've recently converted into 2spd crankset so I've bought a new 2spd road lever. I'm really struggling now to tune the front derailleur. Could you please assist me by answering this questions: Why ...
0
votes
3answers
1k views

gears overshifting issue

As I have explained in my previous post here I have changed my rear shifter cable and housing. But I'm still having issues with shifting gears smoothly. It overshifts at particular gear combinations ...
60
votes
6answers
108k views

What are the pros and cons of internal gears?

I've had my hybrid 24-speed for a bit over 3 years now, and just last weekend, when looking for a bike for my wife, discovered internal gears. Suffice to say it blew my mind when I saw 7-speed ...
19
votes
1answer
2k views

Relative efficiency of different commute bike setups

My interest is in long distance commuting (e.g. more than 50 km a day) and the relative efficiencies of different commute bike setups (e.g. drop bars vs flat bars, fenders vs no fenders, panniers vs ...
18
votes
2answers
43k views

When to change derailleur pulleys?

A friend said me that if you have one part in a very bad condition like a cassette and then you put a new stuff like a new chain it will destroy the new stuff very quickly. A LBS said that I should ...
15
votes
8answers
13k views

If a derailleur cable snaps on a long ride, how can I keep going?

A couple weeks ago I rode around Crater Lake, a 35 mile ride with over 4500 feet of cumulative elevation gain – the sort of ride you really want functional gears for. The night before my rear ...
14
votes
1answer
29k views

Which pulley is which on my Shimano STX RC derailleur?

I disassembled my rear derailleur to clean it; when I removed the sprockets they basically looked the same; both jet black and caked with all sorts of black grease-like-stuff. I figured they were the ...
7
votes
3answers
11k views

Derailleur Pulley Wheel Compatibility

I can't find replacement pulley wheels for my derailer that are explicitly made for it. Should I be safe replacing them with a set with the same number of teeth (i.e., the same diameter) and targeted ...
6
votes
2answers
5k views

Is it practical to replace two sprockets on a cassette?

My bike has 53/39T chainrings and a cassette with 12,13,14,15,17,19,21,23,25 sprockets, but I like to ride up steep mountain roads. Is it possible (without great expense) to replace two sprockets to ...
4
votes
1answer
12k views

Which derailleur should I use with a Shimano 7 speed freewheel 14-34T megarange?

Which derailleur should I use with a Shimano 7 speed freewheel 14-34T megarange in order to prevent the derailleur from rubbing the cassette in 2nd.
3
votes
1answer
1k views

How do I properly adjust a front derailleur?

I have a Shimano FD-TX50. How should I adjust it?
3
votes
3answers
16k views

Front derailleur doesn't seem to be moving

I'm trying to troubleshoot my 24 speed hybrid bike. As it was, the front shifter was having very little effect. I would change gears and not much would happen. When I had a chance to look at it, I ...
1
vote
2answers
4k views

Is this regular chain/pulley noise or is there someting I should check/adjust?

Extra images I'm 99% certain the noise is coming off one or both of the derailleur pulleys, but not sure if it's to be expected or if it's irregular and something that should be fixed? Edit Just ...
12
votes
4answers
6k views

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 ...
7
votes
1answer
3k views

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 ...
7
votes
4answers
4k views

Chain cassette noise

Hello fellow cyclists, I just bought a new Home Trainer that has a Shimano 105 Cassette. My Bike has an Ultegra drivetrain with less than 600km (375mi). I have checked the wear of the chain which ...
7
votes
4answers
2k views

Comparing gear ratios on different bike types

How can I compare gear ratios on different wheel sizes? How can I compare gear ratios on MTB with tracking bikes with bigger wheels? How can I compare gear ratios with gear hubs?
6
votes
3answers
11k views

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, ...
6
votes
3answers
3k views

How can I increase the highest gear ratio?

I am looking for some higher cog front gears for an old bike I am considering. I've been away from it for some time and don't know the current number of cogs on the front ring, but I am looking to ...
5
votes
3answers
938 views

How to make a derailleur work in opposite directions?

I am making a bike for a school project that can switch between upright and pseudo-prone position. It has two sets of crank assembly; one on one side of the rear gear set and one on the other; the ...
4
votes
12answers
35k views

Fitting a 9-speed 11-50T cassette on MTB: which derailleur?

I'm trying to understand if its possible to fit a 9-speed 11-50T cassette (found one on Ali) on my MTB. The plan is to go 1×9. The problem is that I can't seem to understand the if a specific ...
4
votes
1answer
10k views

Upgrade Shimano Sora shifters to 105

I want to upgrade my 3x9 Sora shifters to 3x10 105s. However, looking at the Shimano Compatibility Chart, it appears to indicate that I'll have to replace my front and rear derailleurs in addition to ...
4
votes
2answers
3k views

Shimano MegaRange what type?

Can anyone identify this Shimano derailleur?