{"id":46782,"date":"2023-02-24T13:00:00","date_gmt":"2023-02-24T12:00:00","guid":{"rendered":"https:\/\/www.bikeradar.com\/?p=2937"},"modified":"2023-02-24T13:34:19","modified_gmt":"2023-02-24T12:34:19","slug":"a-complete-guide-to-rear-derailleurs","status":"publish","type":"rss_feed","link":"https:\/\/c01.purpledshub.com\/cyclingplus\/rss_feed\/a-complete-guide-to-rear-derailleurs\/","title":{"rendered":"A complete guide to rear derailleurs"},"content":{"rendered":"

Derailleur compatibility, tooth capacity and much more explained <\/p>

By Jack Luke\n \t\t<\/p>

Published: Friday, 24 February 2023 at 12:00 am<\/p>

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Is it time to upgrade or replace your rear derailleur? Do you sit awake at night worrying about what \u2018tooth capacity\u2019 is? Have you ever simply wanted to know absolutely everything there is to know about buying a rear derailleur or wondered \u2018which rear derailleur do I need?\u2019 If so, you\u2019ve come to the right place.<\/p>\n

While we don\u2019t recommend you break out this hot derailleur chat at your next party, this is essential information if you\u2019re looking to buy or upgrade a rear derailleur.<\/p>\n

In this guide, we\u2019ll take you through rear derailleur compatibility for both mechanical and electronic groupsets<\/a>. We also explain key rear derailleur specs and tooth capacity.<\/p>\n

This article only covers rear derailleurs. We have a separate guide dedicated to front derailleurs<\/a>.<\/p>\n

Which brand of derailleur should I buy?<\/h2>\n
\""Merida\"<\/picture><\/div>
Dura-Ace R9200 is Shimano\u2019s top-flight road groupset.\u00a0<\/span> <\/figcaption> Russell Burton \/ Immediate Media<\/i> <\/span>\n<\/div> <\/figcaption><\/figure><\/div>
\""SRAM\"<\/picture><\/div>
Red eTap AXS takes SRAM\u2019s top slot on the road.\u00a0<\/span> <\/figcaption> Steve Sayers \/ Our Media<\/i> <\/span>\n<\/div> <\/figcaption><\/figure><\/div>
\""Campagnolo\"<\/picture><\/div>
And finally, Super Record EPS 12 is Campagnolo\u2019s premium road groupset.\u00a0<\/span> <\/figcaption> <\/span>\n<\/div> <\/figcaption><\/figure><\/div> <\/div>\n<\/div>\n<\/div>\nShimano, SRAM and Campagnolo are the three main players in the drivetrain market.\n

Microshift<\/a>, Box, Rotor<\/a>, FSA<\/a> and others also make groupset components, but it would be beyond the scope of this article to cover all of these.<\/p>\n

As a general rule of thumb, it\u2019s best not to mix and match drivetrain components from different brands. While cranksets<\/a>, chains<\/a> and cassettes<\/a> are mostly inter-compatible between brands, generally speaking, shifters and derailleurs aren\u2019t.<\/p>\n

This is because Shimano, SRAM and Campagnolo all use different cable pull ratios.<\/p>\n

Cable pull ratio is the amount a derailleur moves for every millimetre of cable pulled through by the shifter. Mixing parts with different cable pull ratios will result in very poor shifting.<\/p>\n

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Generally speaking, road and mountain bike groupset components will not work with each other.<\/span><\/figcaption> Various<\/i><\/span><\/div>\n

However, it\u2019s more complicated than that.<\/p>\n

Mountain bike groupsets <\/a>and road groupsets<\/a> \u2013 even when they\u2019re from the same brand \u2013\u00a0 typically use different cable pull ratios.<\/p>\n

Furthermore, cable pull ratios also differ between different \u2018speed\u2019 groupsets. For example, an 11-speed Shimano road bike groupset has a different cable ratio from a 10-speed Shimano road bike groupset.<\/p>\n

There may even be pull ratio differences between different generations of groupsets with the same number of gears.<\/p>\n

There are, of course, exceptions \u2013 many\u00a0Sramshimpagnolo mash-ups that can be cajoled into working.<\/p>\n

However, it\u2019s usually easiest to stick to the same brand as your shifters when buying a rear derailleur.<\/p>\n

How many gears does my bike have?<\/h2>\n
\"""\"<\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/picture><\/div>
To work out how many \u2018gears\u2019 your bike has, count the number of sprockets on your cassette.<\/span><\/figcaption> Jack Luke \/ Immediate Media<\/i><\/span><\/div>\n

Once you\u2019ve settled on the brand, you must now determine the number of gears your drivetrain has.<\/p>\n

If you are replacing an existing derailleur on a bike, simply count the number of cogs on your cassette and you\u2019re good to go.<\/p>\n

If your drivetrain\u2019s speed is an unknown quantity, you can count the number of steps your shifter runs through and add \u2018one\u2019 to determine the number of gears your drivetrain has.<\/p>\n

Derailleur compatibility explained<\/h2>\n
\"""\"<\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/picture><\/div>
Compatibility across Shimano\u2019s road and mountain bike groupsets is a little bit complicated.<\/span><\/figcaption> Steve Behr \/ Immediate Media<\/i><\/span><\/div>\n

As a general rule of thumb, you shouldn\u2019t mix and match groupset parts of different generations or mix mountain bike and road components, but there are a few exceptions. Below, we have broken down compatibility by manufacturer.<\/span><\/p>\n

For clarity, the following information is applicable to both derailleurs and shifters.<\/span><\/p>\n

Shimano derailleur compatibility explained<\/h3>\n

Shimano road and gravel bike mechanical derailleur compatibility<\/h4>\n
\"""\"<\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/picture><\/div>
Shimano\u2019s road and gravel mechanical shifting tops out at 11-speed.<\/span><\/figcaption> Oscar Huckle \/ Our Media <\/i><\/span><\/div>\n