Surly 135mm (MTB Spacing) Rear Disc Fixed Hub


Manufacturer: Surly
Name: Ultra New Hubs: Rear Disc, 135mm
Over-locknut Dimensions: 135mm Mountain Rear
Axel: Solid, Non-Propietary, Cro-Mo
Rear Mountain Axle: 180×10×1
Thread: English Track Cogs (1.37 × 24tpi)
Lockring: Left-Hand-Threaded (1.29 × 24tpi LH)
Disc Mount: ISO 6-Bolt Disc Rotors
Price: ~$100


A rear disc mountain bike hub for off-road fixed-gear biking. Yes, you read that correctly. It is a specialized part mass produced by Surly.

Special Requirements:

A bike frame with horizontal or track dropouts. Frame also needs to be compatible with rear disc brakes or use a rear disc caliper mounting plate.

What is a Fixed-Gear Bike?

According to Wikipedia, a fixed-gear bike has no free-wheel mechanism. In other words, coasting is not allowed as the pedals spin when the bike is in motion. As a result, a weak braking force can be applied by resisting the rotation of the cranks.

Why Did I Buy It?

Fixed-gear mountain biking off-road is fun, though not very safe. I had a bike with track dropouts and wanted make it an off-road fixed-gear bike with rear disc brakes.

Technically speaking, rear brakes are unnecessary on a fixed-gear bike, but it can be stressful on the legs especially when biking off-road. A rear disc brake would greatly help on some of the steeper technical descents.

Please note that a front brake is necessary for off-road fixed-gear biking.

The other benefit to the disc hub is the ability to attach an ISO 6-bolt rear cog to the rotor mount. That would make it a fixed-fixed rear hub, though the rear brake would be lost.

Would I Buy this Hub Again?

Absolutely. I’ve taken it for many off-road rides and it works great. The chainline is around 53.5mm which is rare for a fixed hub, but fully compatible with most MTB chainline systems.

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