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Questions tagged [derailleur]

Mechanism to move the chain from one sprocket to another.

48
votes
5answers
90k 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 ...
40
votes
10answers
21k 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?
34
votes
5answers
11k 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 ...
29
votes
11answers
13k views

Is there such thing as an automatic transmission for bikes?

Has anyone ever designed or manufactured an automatic transmission (or automatic shifter?) for cycling? I imagine such a device would automatically change the gearing to allow the rider to maintain ...
23
votes
11answers
5k views

Are there real-life alternatives to the chain+derailleur combo?

I was reading an article about the CeramicSpeed’s Driven concept and, while not interested in the efficiency part, the chainless system reminded me of something I was wondering for some time: are ...
22
votes
5answers
130k 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 ...
21
votes
4answers
17k views

Why has indexed shifting displaced traditional friction shifting?

I really don't like indexed shifters, at least on the front. They're harder to adjust, more sensitive to cable stretching, and limit the number of gear combinations you can use (because you can't ...
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 ...
16
votes
4answers
23k views

How do I prevent the rear derailleur from slipping gears?

What's the best way to tune the rear derailleur of my bike to stop slipping gears? It seems that every time I re-adjust it, the middle/upper gears are perfectly aligned, but the lower gears never ...
16
votes
2answers
33k 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
3answers
5k views

Is it normal for my derailleur cables to cross over on the down tube?

I've just picked myself up a Specialized Allez Sport 2014 road bike from Evans Cycles (UK). I test rode the bike and I'm happy with the bike, but when I got home, and flipped the bike over to make a ...
14
votes
7answers
7k 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
2answers
28k 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 ...
13
votes
2answers
840 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 ...
12
votes
2answers
4k views

How efficient is string bike? Is this really a revolutionary bike?

Bicycles are getting evolved with good technologies or methodologies as the period changes. Now, this one bike, so called string bike has been introduced, which doesn't have chain, derailleur but ...
12
votes
5answers
36k 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 ...
12
votes
1answer
5k 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 ...
12
votes
1answer
8k views

Chart for bicycle component quality?

I'm not very familiar with all the different component groups available and wondered if there's a chart that ranks their quality (or price). So I'd know that Shimano 105 is the same level as SRAM ...
11
votes
3answers
51k 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.
10
votes
2answers
2k views

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 upside-down: http://www.zooomr.com/z/...
10
votes
2answers
16k 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. ...
10
votes
1answer
5k views

Is there a downside to spoke protectors?

A few weeks ago, the derailer on my touring bike caught on the chain and ripped itself off the frame. (See the link below for more info on the incident.) The spoke protector was cracked in half by ...
10
votes
5answers
5k views

Why do current, entry-level shimano rear derailers have large-diameter pulleys?

I have seen (and recently bought) entry-level rear derailers from Shimano (Tourney for MTB, 2300 for road bike), and I keep wondering why they are making these parts with such large pulleys. I don't ...
9
votes
6answers
4k views

Mechanic says not to use top three/bottom two gears or the chain will throw

I just bought a BTwin Fit 5, all stock, fresh from the distributor, Decathlon. Took it for light pacing at the store and things seemed OK. About 100 metres out the door, I shift up to the top end of ...
9
votes
3answers
31k 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 ...
9
votes
7answers
64k 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 ...
9
votes
6answers
55k 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 ...
9
votes
1answer
310 views

Setting light to a derailleur

At 3:30ish in this video, they set light to a front derailleur. Why? Degreasing it? Waxy lube that needs melting in? I can't think of a good reason. Any ideas?
9
votes
3answers
36k 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 ...
9
votes
3answers
16k views

Apart from the size, is there any difference between chains for derailleurs or for single-speed / internally geared hubs?

I might need to replace my bicycle chain (see this question). The store where I've bought components before (cyclecomponents.com) seems to be entirely marketed to derailleurs, and I have an internally ...
8
votes
5answers
793 views

What can I do to keep my rear derailler in good condition when commuting in the snow?

In the winter, it seems that whatever I do, my rear derailleur stops functioning after few weeks of commuting in light snow. Ice always gets in there somehow, and the chain refuses to move the wheel, ...
8
votes
3answers
8k views

When to replace rear derailleurs

What is the typical life cycle of mid-range rear derailleurs assuming no accidents? More precisely, what's the average mileage after which it's better to replace it rather than doing tuning all the ...
8
votes
3answers
4k views

Why does my rear derailleur keep breaking?

I upgraded my rear-mech with a new cassette, chain and new cables a few weeks ago since then i've mangled two rear mechs! Both times I've just been riding along; not in a big gear; not at the ...
8
votes
1answer
268 views

Why do deraillers require a freewheel?

I've seen fixies with internal hubs, but a non-freewheeling rear wheel with deraillers seems to be unrepresented: | Freewheel? | Derailler? | Yes | No | ...
8
votes
2answers
2k views

Putting a front Derailleur on a carbon frame

Do you put anything under the clamp on the carbon to protect it? In the past I've tightened brakes on MTB handle bars to much and wrecked them so I'm wondering.
8
votes
3answers
12k 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 ...
8
votes
6answers
42k views

Rear derailleur shifting poorly, skipping gears

I've got a Shimano Sora on a 8-gear cassette, and have odd behavior and skipping, shifting under stress. This started with a trip to the mechanic for a tune up which replaced the chain. I had some ...
8
votes
3answers
1k views

How tight should my chain be?

I recently put new tires on my bike, and in so doing, removed and replaced the wheels. It seems that now my chain has more slack in it than before, and if I pedal backwards while in the smaller cog ...
7
votes
3answers
2k views

Single speed conversion chain keeps derailing rear cog under load?

The chain on my SS mt bike keeps coming off the rear cog under load (like when I hit a steep hill) it will hold right after it's tightened but after a few hills it starts coming off non-stop. Talked ...
7
votes
1answer
449 views

Derailleur On A Single Speed

Earlier today, I saw this bike with an absolutely bizarre drive-train. It looks like a single speed, but it has a derailleur on attached to it. The derailleur does not move horizontally, but only ...
7
votes
3answers
722 views

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 ...
7
votes
1answer
19k 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
1answer
263 views

Why do some people leave the chain sitting on the smaller sprocket when the bike is not used for a while?

I guess it is something related to the springs in the derailleur. But is it that important?
7
votes
4answers
29k 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
1answer
1k 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 ...
6
votes
6answers
7k views

Derailleur adjustment: front or rear first?

When adjusting both front and rear derailleurs, which should be done first?
6
votes
1answer
7k views

How do I tell if jockey wheels need overhaul or replacement?

I am refurbishing a bike and am deciding how much to clean out the rear derailleur. It's in pretty good shape. But after I take off the chain, I tried spinning the jockey wheels with my fingers (...
6
votes
4answers
322 views

Electronic shifters

I have been reading alot about the electronic shifters that are out now, specifically the ones on TREK bikes. I was wondering if they are worth the price, and more importantly how do they perform.
6
votes
3answers
1k views

Different Gear Type when there's no Front Derailleur?

I have a 7 speed Jamis Boss Cruiser, 7 gears in back and one up front. I've been using it fine for several months now. Lately, the chain is coming off of the single front gear, usually after stopping ...
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 ...