Short answer
In many cases, yes. Whether it is practical depends mostly on your frame and rear wheel. There are two main routes: an internal gear hub, or a conventional derailleur and cassette. Both involve replacing the rear wheel, and the second also needs extra components. A bike shop can confirm what your frame will accept.
Check your frame first
Look at these before you buy anything:
- Rear dropout spacing. This is the gap between the rear frame ends where the wheel sits. Single-speed and older bikes are often around 120 mm wide, while many modern geared road bikes use a wider standard. A mismatch can sometimes be handled, but it is worth measuring and checking with a shop.
- Dropout type. Vertical dropouts, horizontal (sliding) dropouts and track ends behave differently. Derailleurs usually need a place to mount, often a replaceable hanger.
- Cable routing. Some frames have cable guides or stops, and some do not. Clip-on guides can help.
- Brake type. Coaster (back-pedal) brakes are part of the hub, so a new hub means a different braking arrangement.
- Tire and chain clearance at the rear.
Option 1: internal gear hub
An internal gear hub replaces the rear wheel hub with one that houses the gears. Examples include hubs from Shimano (Nexus and others) and Sturmey-Archer. The advantages are a tidy look, protection from dirt, and shifting while stopped. Many people choose this route for a bike with narrow rear spacing. The downsides are extra weight, a smaller range than some derailleur setups, and the need to build or buy a matching wheel.
Option 2: derailleur and cassette
This is the conventional geared arrangement:
- Rear wheel with a freehub or freewheel body and multiple cogs
- Rear derailleur, and a hanger if the frame lacks one
- Shifter for the handlebar
- Shift cable and housing
- Chain of the correct width, and sometimes a different length
You may also need a front derailleur and extra chainrings for more range, but many conversions stay with one chainring and a rear derailleur. For parts terminology, see bike gear names, and for how the pieces work together, see our bike gears diagram.
How much does it cost?
It varies widely with the parts you choose and whether you pay for labor. Parts for a basic derailleur setup can be modest, while a new internal hub wheel is usually the more expensive route. Also remember labor if a shop builds or fits the parts. Compare the total with the price of a used or new geared bike. We suggest asking a shop for a quote on your specific bike.
When it may not be worth it
- The frame cannot take a derailleur or has unusual spacing.
- The bike is low-value, so the conversion costs more than a replacement.
- You are mainly trying to ride up a few hills. Changing the single-speed gearing (a larger rear cog or smaller front ring) may be enough.
Why bikes have multiple gears, and how hard single speed is
Gears let you keep a comfortable pedaling effort across different slopes and speeds. A single-speed bike works well on flat or gently rolling ground and is simple to maintain, but steep hills can be hard and high speeds can mean spinning very fast. Learning more about how to pick a gear is easier with a geared bike; see which bike gears to use on hills.