Condensed Answer: Technically, a coaster brake can be mounted on a fixie, but the process will require re-lacing of the rear wheel. Once the coaster brake is installed, the fixie will no longer be a fixed-gear machine because it will have the ability to coast.
What Is a Coaster Brake?
Coaster brakes are drum brakes in the rear hub activated by back-pedaling. When the rider spins the pedals backward a clutch system in the hub pushes a set of brakes shoes against a drum. As a result, the axle has a harder time spinning, and the bike slows down.
If the rider stops back-pedaling, the bike starts to coast (the wheels continue to spin even though the pedals aren’t moving.)
Parts Needed To Install a Coaster Brake on a Fixie
- 120mm O.L.D. Hub with a Coaster Brake
O.L.D. stands for over-locknut dimension and refers to a hub’s width between the two locknuts.
The O.L.D. of a rear hub has to match the spacing between the frame’s dropouts.
Since fixies have 120mm dropout spacing, the free coaster hub needs to have 120mm O.L.D.
- New spokes
The wheel will have to be re-laced with new spokes because the new hub will require a different spoke length.
To find out the length of the spokes that you’ll need, you can use an online spoke calculator.
Re-lacing a wheel is not the most difficult task in the world, and many cycling enthusiasts can get it right with the help of online guides. However, the process will take some time and patience. Some riders may prefer to pay a bike shop to do the re-lacing.
More often than not, this is the faster and better approach because most people do not have the needed equipment (truing stand, dishing tool, spoke wrench, spoke nipple driver) to re-build a wheel.
A Coaster Brake On a Fixie Is an Oxymoron
By definition, a fixed-gear bike does not offer a coasting option since there isn’t a freewheel mechanism. Therefore, if the bike is moving, the cranks and pedals are always turning.
A coaster brake, on the other hand, comes with a coasting ability.
Thus, if you install a coaster brake on a fixie, you will turn it into a single-speed machine with a coaster brake.
The Advantages of Installing a Coaster Brake on a Fixie
1. Less complicated stopping
The standard way to slow down a fixed-gear bike without brakes is to resist the rotation of the pedals. Casual cyclists will find this technique a bit too complicated and uncomfortable.
A coaster brake, on the other hand, is simpler to use and doesn’t require as much strength.
Many people are familiar with it as it was present on children’s bikes back in the day.
2. Better Braking Modulation
The term modulation describes the control that the rider has over the braking force. If a brake has too little modulation, it will essentially come in two modes – on/off. If it has excessive modulation, it will take too much time to fully grab the wheel.
Coaster brakes offer more natural modulation than standard fixed-gear braking.
3. Less Muscle Strain
Fixed-gear braking strains the legs because they have to fight the pedals. On a downhill, that’s exhausting.
4. Less Power Needed To Brake
When doing a basic fixed-gear stop via the pedals, the rider has a poor mechanical advantage.
Conversely, a coaster brake is engineered in a way that greatly increases the rider’s leverage and thus makes stopping less strenuous.
5. Not Affected By Weather Conditions
The braking mechanism of a coaster brake is inside the hub, protected from rain, mud, and other road contaminations. This ensures smoother performance.
6. The Cheapest Way To Add Gears
Rear hubs with internal gears are the quickest and most straightforward way to equip a single-speed bike with extra gears (more).
When making a purchase make sure that the hub has 120mm O.L.D.
The Disadvantages of Installing a Coaster Brake On a Fixie
1. No Longer a Fixie
As already mentioned, a coaster brake/hub turns a fixed-gear bike into a single-speed machine.
Subsequently, some bike snobs may label the conversion as “lame”.
Coaster hubs are more complicated and subsequently heavier than basic fixed-gear rear hubs.
3. Less Effective Than a Front Brake
If you want to increase the stopping power of a fixed-gear bike, a coaster brake is not the best choice because it works on the rear wheel.
During braking, there’s a weight shift to the front which increases the friction between the front wheel and the ground while decreasing the friction of the rear wheel.
Consequently, it’s relatively easy for the rear wheel to get “locked” and skid.
The increased friction makes front brakes more effective.
Therefore, if you want more braking power, it makes more sense to add a front brake rather than mess with the rear braking system.
Alternatively, you could also do both – install a front brake for extra braking power and a coaster brake for convenience.
4. Mechanically Complex
Compared to a fixed-gear rear hub, a coaster hub is mechanically complex. It also needs more maintenance (cleaning, degreasing, replacement of the brake shoes…etc.)
5. No Chain, No Brake
If the chain brakes, the coaster brake can no longer operate. The same applies to regular fixies which is why it is of utmost importance to use strong quality chains.
Hand brakes do not have this problem because they operate independently of the drivetrain.
Therefore, the safest combo is to have two hand brakes plus a coaster brake for convenience (e.g., braking while signaling…etc.) and backup.
Summary: What You Need To Know
- A coaster brake can be installed on a fixed-gear bike, but the bicycle will no longer be “fixed”. Since coaster hubs offer the ability to coast, the bike will transform into a single-speed machine. If the hub has internal gears, the bike will become a full-blown geared bike far away from an actual fixie.
- The conversion will require 120mm O.L.D. rear hub and new spokes to re-lace the wheel.
- The main benefit of coaster brakes is that they allow you to slow down without using your hands, and require less leg strength to brake than a fixed-gear drivetrain.