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Articles about Gears and Drivetrains
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by Sheldon "Shifty" Brown
and John "Sprockets" Allen
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Online Gear Calculator For cyclists who are not mathphobes

You can calculate gain ratios, gear inches, or meters development. with my Online Gear Calculator or with your Slide Rule

Gear Shifting For beginner or intermediate cyclists.

Everything You Wanted To Know About Shifting Your Bicycle's Gears,
But Were Afraid To Ask.

This is an introduction to gear shifting, and the basics of how a derailer works. How, why and when to shift gears.

Derailer Adjustment A step-by-step guide for the home or shop mechanic.

How to adjust your bicycle's derailers for smooth, reliable shifting.

Freewheel or
It isn't all the same to you if you have to replace one!

How to tell them apart.

Cables A guide for the home or shop mechanic.

Many shifting problems are not the fault of the derailer, but result from poorly installed, damaged or corroded control cables.

Chains Something for everybody, from the beginner to the experienced mechanic.

Chain maintenance and lubrication.

Warning: contains un-provable opinions on one of the most controversial subjects in cycling.

Chain wear Mostly technical.

How chains and sprockets engage, and how they wear.

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If the Chain Falls Off -- or if it jams, and you are in a jam too

How to prevent it and what to do if it happens.

Cassettes For the intermediate/advanced cyclist.

Most new derailer-quipped bicycles of good quality use Shimano "Freehubs" and sprocket cassettes for the rear hub, the heart of the gear shifting system. This article explains why, and links to pages listing all commonly available clusters. If you want to customize your gearing to fit your riding style and terrain, this will show you what your options are.

Shimano cassette body types For the cyclist who wants to keep up to date.

As of 2018, Shimano has introduced some new cassette body types, in connection with increased numbers of sprockets and thru axles. This article gives representative examples and discusses compatibility.

Internal-Gear Hubs For the commuter or utility cyclist.

Derailers are not the only option for multi-speed bicycles. Remember 3-speeds? Now you can have a 7, 8, 9 or even 14-speed hub with the same easy, reliable internal gearing.

This page describes how these hubs work and links to many pages with information on maintaining and rebuilding them.

Fixed Gears For the active, vigorous cyclist.

Are you sure you need a bicycle with gears? The purest, simplest kind of bicycle is the fixed-gear bicycle. Riding a fixed gear will make you a stronger, smoother cyclist...and it is a ton of fun!

Gain Ratios For gear-head techno-nerds only!

A new and different way to calculate your bicycle's gears, and to compare the gears of one bicycle with those of another.

Straightening Chainwheels For the advanced home mechanic or shop mechanic.

If your chainwheels are bent, your front derailer can't work properly. This short article deals with strategies for straightening them out.

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Automatic Shifting For the home or shop mechanic.

Does your bike shift by itself when you try to climb hills? This article will tell you why, and help you make it behave itself.

Servicing Freewheels
For the advanced home mechanic
or shop mechanic.

Most rear wheels made before the mid-1980s used freewheels, which thread onto the hub. Some bicycles still are supplied with freewheels, rather than cassettes; replacement freewheels also are available. This article describes the options, and how to remove and replace freewheels. I don't recommend taking freewheels apart, but if you really want to do it, the article will show you how.

SunTour Perfect, Pro Compe and New Winner Freewheels
For the advanced home mechanic
or shop mechanic.

These freewheels are no longer made, but they are very common and offer a wide range of options -- in particular, 5-speeds and 6-speeds that work with older frames. Here's how to choose among these freewheels, keep them going and customize them.

Speeds If you don't think you have enough.

About 7-, 8. 9, 10-11-speed systems: Read this if you might need to mix and match parts made for different numbers of sprockets, or if you suffer from sprocket-count envy.

Sheldon Brown's Bicycle Glossary For all cyclists.

An encyclopedic listing of bicycle lore, technical data and opinions.

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Articles by Sheldon Brown and Others

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Last Updated: by John Allen