Indexed (SIS) vs Friction Shifters: Differences, Pros, and Cons

Both Index and Friction Are Shifter Mechanisms

Index Shifting Is Now the Standard on Modern Bicycles

On modern bicycles—whether road bikes, mountain bikes, mini velos, or even city bikes—if the bike has gears and is newly manufactured, it almost always uses an index shifting system. Shimano’s STI levers for road bikes also use this indexing mechanism.

The word “index” comes from the English word for “reference” or “list,” and in this context, it refers to the shifter having preset positions: “Gear 1 is here, Gear 2 is here,” and so on. The shifter controls how much cable is pulled or released for each gear.

A key feature of index shifting is the noticeable clicking steps in the shifter. The amount of movement by the derailleur is precisely determined by the shifter for each gear change. When properly adjusted, this allows for incredibly smooth and accurate shifting.

Index shifting was originally developed by Shimano and is now used in almost all modern bicycle drivetrains. If you see the abbreviation “SIS” on Shimano gear components, it stands for Shimano Index System.

SIS Rear Index Shifting System

Since the number of index positions is predetermined by the shifter, it’s essential to use a shifter that corresponds to the number of gears.

Friction Shifters: Once the Standard

Friction shifters are the opposite of index shifters. They are often referred to as “continuously variable” because the shifter has no preset positions. In the past, friction shifters were the standard, and some road bikes still use friction-type W levers.

Unlike index shifting, the amount of derailleur movement in friction shifting is determined by how much the lever is moved. Without the indexing, friction shifters can support multiple gear options.

A benefit of friction shifting is that it allows fine adjustments. However, the downside is that if the rider isn’t careful, the gear change may not be smooth.

Riders who are used to index shifting may find friction shifting a bit inconvenient.

Which is Better: Index Shifting or Friction Shifting?

Both index and friction shifters have their advantages and disadvantages, and the choice between the two often comes down to the rider’s personal preference.

However, since most modern bikes come with index shifting, most riders today use index systems.

Index shifting is compatible with most bicycles, but friction shifting requires a specific setup, such as a W lever mount. So, the choice of frame may influence the shifter you can install.

An exception is Shimano’s grip shifters, where friction-type shifters are available for the front derailleur.

Should You Avoid Friction Shifter Complete Bikes?

Some of the complete bikes on the market today come with W levers. Should these bikes be avoided?

If you plan to upgrade the components of your road bike or cross bike in the future, we would not recommend bikes with W levers. This is because the shift routing is different from that of index shifters, and the frame may not have the necessary mounts to install index shifters.

Bicycle shifting systems are simple, but they often require adjustments, and if the frame doesn’t have the necessary mounting points, installation can be tricky. If you want to use index shifters, it’s better to choose a complete bike that already has index shifting.