Road Boost Spacing

What is Road Boost?

“Road Boost” is a term which refers to the width and thru-axle size of some frames and hubs.  It means that front hubs are 110mm wide, rear hubs are 148mm wide, and both use a 12mm diameter thru-axle.

Despite the name Road Boost it’s mainly gravel bikes and e-bikes where we see this hub spacing, not ‘normal’ disc brake road bikes, and definitely not rim-brake road bikes.

Please note this article relates to Road Boost.  We have a separate page for mountain bike Boost.

How do I know if my existing bike is Road Boost?

We strongly suggest that you measure your frame and fork yourself, as relying on a bike manufacturers website can be dangerous as the hub spacing can change from year to year, even on bikes with the same model name.  It doesn’t take long to do, and this way you’ll know for sure.  We put together this video to help:

Can I convert regular road wheels into Road Boost?

Yes, you can, although this will be hub-dependent.  It’s worth noting that since these conversions will widen the endcaps not the hub shell you won’t enjoy the benefit of extra wheel stiffness by using them, but they will allow you to use non-Boost wheels in your new Boost frame.

There are two types of kits:  Those which require the wheel to be re-dished and those that do not.  We go to painstaking lengths to ensure that the spoke length on our wheels is perfect so we generally do not like kits which require the wheel(s) to be re-dished, however because of the difficulties raised by center lock disc brake rotors and flat-mount disc brakes these kits are currently more common.

Please see the list at the bottom of this page for help on how to convert your current hubs to Road Boost.

Can I convert my frame into Road Boost?

No.  The width of the front and rear dropouts isn’t adjustable.  A non-Boost frame or fork is forever non-Boost, and a Boost frame or fork is forever Boost.

What new wheel options do you have for Road Boost?

If you’re buying new wheels from us, lots.  We’re ahead of this new hub size and we’ve got Road Boost front and rear hubs available from Dial, Hope, DT Swiss, Industry 9, and more, and we can custom build these into a range of carbon or aluminium rims depending on your use and your budget.

Differences between Mountain Bike Boost and Road Boost

At the back of the bike, Road Boost and Boost are exactly the same thing – 148mm wide and using a 12mm thru-axle.  The term “Road Boost” is redundant here, and makes things confusing.

At the front of the bike both Road Boost and mountain bike Boost hubs are 110mm wide but Road Boost uses a 12mm thru-axle, and mountain bike Boost uses a 15mm thru-axle.  Confusing?  Yes.  Why didn’t we just stick with the 15mm thru-axle of mountain bike Boost hubs and then we’d have one less incompatibility to worry about?  There are industry claims of reduced aerodynamic drag and decreased weight by using a 12mm axle rather than 15mm, however these claims are dubious at best.

How did Road Boost come to be?

To understand why we’ve got this confusing new term we need to understand where we’ve been.

Back in 2015 the mountain bike industry created Boost hubs by taking the ‘standard’ sized and widened them.  This did two important things:  

First – Wider hubs build into stiffer wheels, something which was especially important for the newfangled 29” wheel size.

Second – Because the rear hub is wider the entire drivetrain is moved outwards slightly, so the crankset also needs to be wider.  This gains a precious few millimetres of space behind the bottom bracket, giving extra clearance between a big fat tyre and the chain, and giving extra room for suspension pivots and ebike electric motors.

Those two advantages of extra stiffness and extra clearance come with only one small downside, which is an extra few extra grams of hub and thru-axle weight.  Boost hubs caught on and quickly became the norm on mountain bikes.

It’s important to note that the extra width comes from the center of the hub between the flanges, pushing them out wider, not at the endcaps.  

Fast forward to today and gravel bikes and ebikes are running into the same problems – tyres are getting fatter causing issues with the chain catching on the rear tyre, and an increased number of ebike motors are being shoehorned into frames.  Bike companies have responded by Boosting the hubs to get those same advantages of increased wheel stiffness and increased clearance that mountain bikes enjoy.

Common hubs and how to convert them to Road Boost

Note: All of these suggests assume you start with a front 100x12mm front hub and want to convert to 110x12mm; and that you start with a rear 142x12mm rear hub and want to convert to 148x12mm

Chris King R45 Center Lock

Front: There are two options: Our Generic Front Hub Road Boost Adapter will require the wheel to be re-dished. Alternatively our Generic Front Hub Center Lock to 6-bolt will also work but require you to use a 6-bolt rotor.

Rear: Our Generic Rear Hub Adapter is the best option.

DT Swiss 240s or 350s Center Lock (excluding EXP version)

Front: There are two options: Our Generic Front Hub Road Boost Adapter will require the wheel to be re-dished. Alternatively our Generic Front Hub Center Lock to 6-bolt will also work but require you to use a 6-bolt rotor.

Rear: The ZRace kit is the best option which will require you to convert to a 6-bolt rotor.

DT Swiss 240s or 350s 6-bolt (excluding EXP version)

Front: Our Generic Front Hub 6-bolt kit is the best option

Rear: Our Generic Rear Hub Adapter is the best option.

DT Swiss 240s EXP Center Lock

Front: There are two options: Our Generic Front Hub Road Boost Adapter will require the wheel to be re-dished. Alternatively our Generic Front Hub Center Lock to 6-bolt will also work but require you to use a 6-bolt rotor.

Rear: The ZRace kit is the best option which will require you to convert to a 6-bolt rotor.

Hope Pro2 / Pro2 EVO / Pro4

Front: Our Generic Front Hub 6-bolt kit is the best option

Rear: The Hope kit is the best option.

Wheelworks Dial Center Lock

Front: There are two options: Our Generic Front Hub Road Boost Adapter will require the wheel to be re-dished. Alternatively our Generic Front Hub Center Lock to 6-bolt will also work but require you to use a 6-bolt rotor.

Rear: The ZRace kit is the best option which will require you to convert to a 6-bolt rotor.

Wheelworks Dial 6-bolt

Front: Our Generic Front Hub 6-bolt kit is the best option

Rear: Our Generic Rear Hub Adapter is the best option.

Other brands 6-bolt

Front: Our Generic Front Hub 6-bolt kit is the best option

Rear: Our Generic Rear Hub Adapter is the best option.

Other brands Center lock

Front: There are two options: Our Generic Front Hub Road Boost Adapter will require the wheel to be re-dished. Alternatively our Generic Front Hub Center Lock to 6-bolt will also work but require you to use a 6-bolt rotor.

Rear: The ZRace kit is the best option which will require you to convert to a 6-bolt rotor.