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Project Sports

Questions and answers about sports

Installing modern Deraileurs in an Old type mountain bike Frame

5 min read

Asked by: Clint Howard

Are derailleurs interchangeable?

As a general rule of thumb, it’s best not to mix and match drivetrain components from different brands. While things such as cranks, chains and cassettes are mostly inter-compatible between brands, generally speaking, shifters and derailleurs aren’t.

Can I upgrade my rear derailleur?

The number of gears supported changes



The higher the grade of Shimano rear derailleur, the more gears it can handle. For both road bikes and MTBs, 12-speed is the maximum number of gears supported. Of course, upgrading between 11-speed derailleurs will not change the number of gears supported.

Are bicycle derailleurs interchangeable?

No, bike derailleurs are not universal. A derailleur that works with one bike may not work with another bike based on factors such as the cage length. Check the difference between the smallest and largest cogs and also the chainring size to determine the derailleur compatibility.

Are all rear derailleurs the same?

Rear derailleurs vary in the length of the cage, or the amount of spacing between the top pulleys and the bottom. This length determines how many gears the chain can accommodate — a longer cage length can take in the slack from a larger range of gears, while a shorter chain is designed to work with a smaller range.

How do I install a new derailleur?

Quote from video: So if you just kind of swing the tail of the derailleur up high so that bolt clears that tab. Then just take your 5 mil. And start turning it clockwise. The derailleur will thread right on there.

What is the difference between a long cage and short cage derailleur?

Quote from video: So that cage has had to move right forward. Now the longer the cage the more of a difference in ratio between the smallest and biggest sprockets.

Do I need a new derailleur if I get a bigger cassette?

You’ll have bigger jumps between the gears, but you’ll have a bigger range of gears. With a wider range cassette, you may need a new rear derailleur with a longer cage.

What does a derailleur extender do?

What Derailleur Extender Do? The derailleur extender will make the original hanger longer and lower the rear derailleur, to put the upper jockey wheel under the bigger cogs to make the shift possible, mostly needed when upgrading to a big ratio cassette.

Do I need a new chain if I get a bigger cassette?

Generally Yes you have to change your chain. The only time you might get away without changing chain is if its JUST been replaced. That is, under a hundred km of riding or in the last ~week. Running an elongated chain on a new cassette dramatically increases wear on the cassette.

How do you change a derailleur on a mountain bike?

Quote from video: Put the mech to the smallest sprocket using your sti's. Pull the cable crimp off the end of the inner cable using some pliers then undo the cable crimper bolt by unscrewing it anti-clockwise.

How do I know what derailleur I need?

When buying a new rear derailleur be sure to match it with your drivetrain ‘speed’. 10-speed drivetrains use narrower chains than 9-speed so you’ll need a mech to match. Most rear mechs are made of a polymer and alloy mix but you’ll find carbon fibre in top-end models to shave even more weight.

Can you use a 7-speed derailleur on a 8 speed cassette?

yes it will work.

How much does it cost to replace a rear derailleur?

If you take your MTB into a local bike shop the average price to replace a rear derailleur is going to be $110. If you DIY replacing a derailleur will cost about $50 (plus your time) This price will depend a lot on the actual derailleur needed. Usually a bike shop will also take care of other problems.

How do you mount a Shimano rear derailleur?

Quote from video: And it goes round the cassette up. And over the top jockey wheel down. And into the cage. And then around the bottom of the bottom jockey wheel so just make sure you're doing that correctly.

How do you install a front pull top derailleur?

Quote from video: For the angle adjustment rotate the derailleur until the cage is parallel with your chain rings. Then fully tighten the clamps mounting bolt if your chain is still on the bike undo.

Can I use SRAM derailleur with Shimano cassette?

Considering these parts were never designed to play well together, the Sram GX AXS shifter and derailleur work perfectly on the Shimano XTR cassette.

Can you use a 12 speed derailleur on 11 speed cassette?

So you can’t use a 12 speed derailleur on an 11 speed setup or vice versa but you can you an xtr 12/11 speed shifter on an 11 speed drivetrain.

Can I use an 8 speed derailleur on a 7 speed cassette?

8 speed shifter and cassette, 7 speed derailleur? You’ll be fine. There’s no “probably” about it. 6-, 7- and 8-speed gear is all cross-compatible in terms of chain width.

Can I use a 9 speed derailleur on a 7 speed cassette?

Can I use a 9-speed derailleur on a 7-speed cassette? The answer is yes because the rear shift ratio of 9-speed and 7-speed derailleurs is the same if you stay within the same brand.

Can a 10 speed derailleur work on a 8 speed cassette?

You will need a 10 spd rear derailleur to work with a 10 spd cassette, because the spacing is smaller with a 10 spd setup. You will need a 10 speed chain for a 10 speed setup, a 9 speed chain for a 9 speed setup and any 8 speed chain will work on 8-7-6 speed or lower.

Are 6 7 8 speed chains the same?

Chains for 6-, 7-, or 8-speed cassettes are generally universally compatible across brands and speeds. That means if a chain says “8-speed Shimano” you can use it in your old 6-speed, too.