from Rookie’s keyboard

Hello, friends

The other day a guy asked me what kind of brakes he should run on his fixie. I told him that the classic option is to get a front rim brake and rely on the pedals when to slow down the rear wheel. (It’s a fixie after all). 

But then he said, “Why not a disc brake?” and got me thinking. There is no denying that this choice is unorthodox for a fixie, but it can certainly work. 

How? 

The most straightforward way to equip a fixie with a disc brake is to buy a fork with a disc brake mount.

A “fork swap” isn’t the easiest task, but it’s not super complicated either. Most semi-dedicated mechanics can do it successfully after educating themselves via YouTube videos.

Don’t forget that the front brake provides most of the stopping power. During braking, there’s a weight shift to the front resulting in better traction of the front wheel. Hence front brakes are more effective.

The downsides of this method are:

• Slightly different geometry

If the new fork doesn’t match the ATC (axle-to-crown) length and the rake of the original, the geometry of the bicycle and subsequently the handling will be affected.

The truth, however, is that it will be difficult to find a fork that answers those criteria 100%. In most cases, you will have to compromise and get one that fits as close as possible.  

• Retro Bikes Are Out of Luck

If your fixie is modern, it will be equipped with a threadless headset and a basic 1 1/8″ fork.

Those forks come with a long steerer that you cut according to your needs by using a hacksaw or a pipe cutter.

Older fixies with threaded headsets and forks make this mod very difficult because fewer threaded forks answer the criteria. In the best-case scenario, you will find a threaded fork as long as the old one.

Technically, threaded forks can be cut too, but the process is more complex because they have to be re-threaded. So, forget about it. Most bike shops do not have the tools to complete this procedure because the technology is considered old-school.

New looks and color

Disc brake forks have a modern vibe that may not complement the look of a traditional steel fixed-gear bike. And obviously, the fork will be a different color. That’s not always bad as sometimes a contrast between the frame and fork adds style points.

Important Note:

Many people will be tempted to weld (or pay someone to do it) a disc brake mount onto the existing fork. Don’t.

Rim brake forks are not strong enough to handle the torque of disc brakes. If you install a disc brake mount on a rim fork, the disc leg of the fork may bend during braking.

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Summary of The Needed Parts(Front Only)

If you want to run a front disc brake on a fixie, you will need:

• A new fork (with disc mounts)
• Disc brake
• Brake cable and housing or a hydraulic system
• A brake lever 
• New front wheel with a disc brake-ready hub
• Cable stoppers for the brake cable as fixed-gear frames come without those

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Adding a Disc Brake To The Rear?

Installing a rear disc brake on a fixie is a highly problematic endeavor and honestly pointless.

The issues are:

• No Disc Brake Mounts

Fixed-gear frames do not have mounts for a disc brake. And the only option is to weld one. The procedure requires machining, welding, grinding, sanding, and re-painting of the area. If you don’t have the necessary tools, expertise, patience,, and time, just find something better to do.

• Weak Chainstays 

Disc brakes stress the frame. Therefore, frames that aren’t designed for disc brakes will most likely deform unless the rear triangle is reinforced with a brace. (A piece of metal welded to the chainstay and the seatstay on the disc brake side.)

The procedure mentioned above will void the warranty of the frame.

• Narrow O.L.D.

O.L.D. stands for “over-locknut dimension” and indicates the usable part of a hub between the two locknuts.

The O.L.D. of a wheel should match the rear spacing of a frame. Otherwise, the wheel won’t slide in.

Fixed-gear rear wheels have a 120mm O.L.D. whereas rear road wheels with disc brakes have 135mm O.L.D.

A rear road wheel won’t fit on a fixie unless the frame is cold-set (bent). Cold-setting can be done only on a steel frame and voids the warranty.

You will need a 700c fixed-gear wheel with a disc-brake-ready hub – a rare part absent from most bike shops.

Of course, you can build the wheel yourself. You will need a fixed-gear rear hub designed to take a disc brake(e.g., Novatec D566SBT 32) and new spokes.

• Chain tension issues

Putting on the rear wheel on a fixed-gear bike and acquiring the correct chain tension is hard enough as it is. А disc brake complicates the rear wheel installation process even more.

• Redundancy

Fixed-gear bikes already have a rear brake (the pedals/cranks)

Honestly, don’t do it. 

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Summary of the Benefits

• More braking power

This is the main one. Disc brakes offer the highest braking power. They beat rim brakes in wet and even dry conditions.

• The rims don’t have to be replaced as often

Unlike rim brakes, disc brakes do not wear down the rim. Thus, the rim is no longer disposable.

• Points for a Unique style

Fixed-gear bikes with disc brakes are a rarity.

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The Downsides

• Extra Cost

Disc brakes cost more than rim brakes.

• Extra weight

Disc brakes are heavier than no-brakes or rim brakes.

• Different Aesthetics

Disc brakes alter the aesthetics of the bike.

Fixie Riders Don’t Want Disc Brakes

Let’s be real – fixed-gear bikes are all about simplicity. And disc brakes just don’t fit in “culturally”.

Just because you can, it doesn’t mean you should. 

But ultimately, the choice is yours. It’s tricky. Potentially pointless. But it can be done.

Until next time

-Rookie