Become a Member

Get access to more than 30 brands, premium video, exclusive content, events, mapping, and more.

Already have an account? Sign In

Become a Member

Get access to more than 30 brands, premium video, exclusive content, events, mapping, and more.

Already have an account? Sign In


Cyclocross Racing

Boost in ‘cross, or foot in mouth?

It seems thru-axles just entered the cyclocross world, so why are we talking about Boost? It could work, but that doesn't mean it will.

Heading out the door? Read this article on the new Outside+ app available now on iOS devices for members! Download the app.

It’s not difficult to find a cyclist who treats innovation with a skeptical eye. Innovation often hits the wallet hardest, and new tech may or may not actually benefit the rider appreciably (see: the current bottom bracket “standard” debacle). Innovation itself isn’t the problem — it is, instead, the cycling industry’s historic inability to get on the same page, to allow consumers to upgrade without having to buy an entirely new bike to take advantage of new tech.

Recently, I wrote a review of Cannondale’s SuperX cyclocross bike and bemoaned its lack of thru-axles. In that same article, I contended that Boost 148, a new hub spacing standard in the mountain bike world, could be the future of cross.

The blowback was instant, and it was fierce. And I can sympathize. Along with the confusing mire of bottom bracket sizes and specs, why make a mess of axle spacing and spec too? Is there a real benefit? Quick releases seem to work just fine; why tinker with what works? Haven’t we already seen this story all too often in the cycling world?

In response to the backlash about thru-axles and Boost 148, I decided to see if bike manufacturers might have some insight here, so I contacted a few — from small frame builders to the biggest names in the industry — to see if I was right or if I needed a crowbar to pull my foot out of my mouth.

I told you so

“From our standpoint, the 142×12 standard is the most practical for the CX application,” says Brad Cole, associate brand manager at Niner Bikes. “The stiffness benefits over a traditional 135 QR, and additional wheel retention security, could not be ignored.”

And thru-axles are indisputably stiffer. The question is, can all riders benefit from them? Possibly not, and any time the industry shifts to a new ‘standard,’ it’s important to remember one thing: You don’t have to upgrade. If you’re looking for marginal gains to reach the podium, upgrade to the next category, or just get faster, ignoring the benefits could be folly, especially if the competition is embracing it.

“One benefit [of Boost 148] to ‘cross racers could be the stiffer wheel from the wider hub flanges,” says Whit Johnson, founder and frame builder at Meriwether Cycles. “For the racing honches, a stiffer wheel would make sense and if 148 does, in fact, allow that.”

Wider hubs and bigger axles translate into wheel stiffness on tall wheels, which should, in theory, translate into better tracking through corners and better power transfer when you stand up and mash. The VeloNews review of the SuperX, in fact, addresses this very point because we happened to be in the midst of testing several cyclocross bikes, and the thru-axle models definitely tracked better than quick-release models. That’s a subjective assessment, mind you, but it was a consistent subjective assessment from several testers.

Indeed, even companies that have held onto the QR in the rear have upgraded the front wheel to a thru-axle. Trek’s 2016 Boone, for example, has this very configuration. No company has plans to make the jump to Boost, but it seems unanimous that there is a tangible benefit to thru-axles. Michael Mayer, global road brand manager at Trek Bicycles, said, “we constantly evaluate all technology based around the benefit for the rider. If the future evolves to Boost or any other technology being the best benefit for the rider performance without sacrificing ride quality we will be looking at it.”

Okay, maybe I didn’t tell you so

It seems like a no-brainer then, right?

Not so fast.

“Chainline,” says Johnson from Meriwether. “Remember that mountain bikes use a 73mm BB shell, if not 83. The Boost was created for the demand for the new, bigger ‘plus-sized’ tires and the wider chainlines (to allow for bigger tires on short chain stays). A stiffer wheel was kind of a perk of moving the chainline wider. In my opinion, it was a marketing add-on.”

Cole from Niner agrees. “There is definitely some intrigue in the idea of moving to a Boost standard, but there are some large hurdles that would have to be overcome to make that switch,” he says. “The advantages of Boost spacing on mountain bikes is pretty clear right now, not only in wheel stiffness but secondary advantages in frame design where chain stays can be shortened and tire clearance maintained.”

But the bottom bracket, Cole says, is problematic on a cyclocross bike. “To move to a Boost rear end on a CX bike, it would likely force manufacturers to have to move to a wider bottom bracket shell to accommodate the additional clearance. This move is going to push the chainstays outward, as it does on mountain bikes, which is going to cause issues with crank clearance.”

So the move to Boost would take an industry-wide shift, which we have seen with bottom brackets, with thru-axles, and with countless other tech advances that were belittled and bemoaned when first introduced. That process is slow, and it can be expensive. More importantly, it can irritate a lot of bike customers who are tired of pulling out the pocketbook just to keep up.

It would essentially take a larger bike company to gamble, investing time and money into redesigning the cyclocross bike from the ground up. Trek and Specialized would of course be the two biggest players with that kind of time and money, but the job wouldn’t be an easy one — or a quick one. “Since the chainstay length on a CX bike is shorter than on a mountain bike,” says Cole, “the stays would likely need to stay quite close together near the bottom bracket and flare outward pretty dramatically towards the dropouts to maintain heel clearance. This design may likely negate all of the stiffness gains from the Boost spacing. So could it happen? Maybe, but there will have to be some fairly large changes in design and also spec as it relates to fit before it could come to reality.”

Boost could add benefit to a cyclocross bike, but Cole makes a valid point: “It seems that ‘cross bikes are stiffer and more efficient than they have ever been. I think at a certain point this stiffness may offer diminishing returns; a little bit of flex and compliance is definitely not a bad thing when racing off-road. While you don’t want the bike to sacrifice any efficiency, a tiny bit of flex can help to make up for mistakes in line choice on rough terrain.”

So will it happen? Will Boost hit the cyclocross world with force in the next few years and revolutionize the way ‘cross bikes handle? Or is the time and effort too much, and the payoff too little, to really be a viable option? For the time being, it’s safe to say thru-axles are here to stay, and there’s real benefit to them. As far as Boost goes, well, when it comes to new tech, no one’s doing it — until someone is. It only takes one design to start the trend, like the sudden growth of 29ers a decade ago; the question is whether anyone will seize on that potential for Boost in ‘cross, and whether it’s worthwhile to pursue it.

An American in France

What’s it like to be an American cyclist living in France? Watch to get professional road cyclist Joe Dombrowski’s view.