The rapid growth in disc brakes for road bikes has catalysed the uptake of thru-axles. Marc Abbott asks if this mountain bike technology will soon replace the humble skewer

When Tullio Campagnolo invented the quick-release skewer almost 90 years ago, even he, as the father of Italy’s groupset giant, couldn’t have imagined that his simple idea would become the industry standard.

Designed for race use, where time is everything, a system that allowed a wheel to be dropped out for changing (or, in Campagnolo’s case, flipping, to use the secondary gear on the other side of the hub) was always likely to gain favour. As with so much race technology, the humble quick-release filtered down to the bikes we grew up riding.

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But leaps forward in bike design often demand new approaches. The advent of disc brakes on road bikes has necessitated a change in thinking when it comes to maximising stiffness and minimising losses, provoking manufacturers such as Focus, Boardman and Colnago to take their lead from the dirt bike world.

Their use of a thru-axle, a pin that needs to be pulled completely through the spindle before the wheel can be removed, has sound foundations.

“The big advantage is the stiffer load path between the caliper and rotor,” says Keith Bontrager, arguably the godfather of modern mountain bike development, and now component developer for Trek.

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“Flexing in the axle or dropout on the brake side will allow the rotor to shift and contact the brake pads, causing the brake to drag. It’s noticeable when climbing out of the saddle. The large axle and rigid connection between the axle and dropout minimises that.”

With such a clear performance benefit, surely everyone is swapping to thru-axles? Not so, says Zipp’s wheel development director Michael Hall: “Zipp continues to design wheels/hubs that allow the rider to easily change between quick-release and thru-axle.

“Our 77/177D disc brake hubs are actually supplied to the customer with both quick-release and thru-axle end-caps, so they can make the decision.”

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Which, for now, means the customer looking to upgrade still gets a choice. But what’s the flip side?

“The disadvantages are that [the thru-axle] can add a bit of weight, and removing and replacing a wheel becomes more time-consuming,” says Bontrager. “That time issue is a minor annoyance for most riders, but pro teams will have to work out a way to swap a wheel quickly in a race. It might mean bike swaps become more common.”

The increased use of disc brakes prompts a broader question: how much will frame and wheel design change?

“Thru-axles are something new that will change bike and frame design,” reckons Hall. “As for wheels, disc brakes open up opportunities for advancements in rim design, since we are not as limited by a brake caliper or chainstays. For instance, rims can certainly get wider.”

Bontrager takes the position that mountain biking has done the hard work for us, adding: “There are a few things that change when you design a disc wheel or thru-axle, but most of those have been addressed with off-road wheels and are well understood.”

The key question is, if there’s a clear performance benefit to be had from switching to a thru-axle setup, will that be reflected at your local bike shop?

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“Stocking both will require the dealer’s inventory to be a bit deeper,” says Bontrager. “That might make getting a specific spare tougher in some cases.”

Bontrager also highlights the more secure nature of the thru-axle: “[US firms] may move away from quick-release to reduce the problems with product liability… Incorrect use of QRs continues to be a problem in the States.”

Our take

It’s time to take a long, hard look at ourselves and ask whether it’s weight or stiffness that’s the most important factor in our bike-buying decision. Rim brakes with QRs will have their place for years to come, but if you want to make the switch to disc brakes, bolt thru-axles are the obvious, future-proof choice.

Yes: Keith Bontrager, father of modern MTB and component developer for Trek

Keith-Bontrager

“It’s likely that thru-axles will become the industry standard eventually, down to a certain price point. I don’t know what the timeline will be, but if it’s anything like the wheel size thing in mountain biking, where the 26-inch option was rapidly removed with the introduction of 650b and the 29er, I think it could happen quickly.”

No: Michael Hall, Zipp wheel development director

alistairs_bike_-_zipp_404_-_cbrakethrough_media

“We want to provide the best options for our customers. Zipp continues to design wheels and hubs that allow the end user to easily change between quick-release and thru-axle. Our most recent disc brake hubs, for example, allow the rider to change between quick-release and thru-axle simply by swapping the end-caps by hand.”

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  • Ken Scott

    The answer to the question posed is yes. The aircraft industry went from the Wright brothers to the moon in less than the average life span. Yet it is taking the bike industry nearly a hundred years to get over the quick release. Really a hundred years of using a design that is not the best solution to the problem. All this does is point out the glaring lack of progress the bike industry has made. Up until the last thirty years. Yes those guys in Marin county got things going. They weren’t the only ones riding bikes in the woods. My friends and I were ridding single track trails though the woods back in the late sixties. The difference was that we were kids on our Schwinn Sting Rays. We were primed to become the adults who would gladly go play in the woods on bikes. Something that I gladly began to do once again in ’82’ when I converted my old Schwinn Varsity into my first Mtn. bike.

    There simply is no argument not to make this change. It is time for the last two parts of the bicycle that have not changed to do so. Rim brakes and quick release skewers have had there century. It was the last one, time to move on to the current century. Too heavy? They have made ride able bikes that weigh less than your average toy poodle. Too slow to get the wheel out. Give the engineers a minute and that one will go away to. I don’t agree with this one by the way. I have watched mechanics changing wheels in the Tour. I have done it quicker with my through axle rear wheel on my Scalpel. Come on people an F1 pit crew can change all 4 wheels on the car in 2.5 seconds! Trust me the through axle will become far faster to take off than any QR skewer could ever possibly match. Not to mention that in the long run the through axle will be less expensive to manufacture. There is only one part to the simplest of them. The simplest QR skewer I have seen still has at least four. Remember people K.I.S.S. (keep it simple stupid). Fewer parts fewer things to go wrong.

  • xcplanet

    Agreed that calling Bontrager a godfather of mountain biking is an overstatement. Perhaps in the truest sense of the word (not the father or mother, not a grandparent, not related but perhaps gave a bit of support here and there). There are plenty of other names with bigger contributions. Mostly, the name is a sub-brand of Trek that tries to lend some apparent cachet to less expensive components.

  • John Senior

    Thru axles on mountain bikes are a no brainer – they’re stronger with little weight penalty – make no sense on road bikes and if Ian Stannard can come down a Pyrenean descent using a standard QR then there is no argument for anyone else adopting them – on a disc wheel they might make more sense due to the braking strain being at the rotor rather than the rim- but even that isn’t certain.

  • David Bassett

    Were oh were are you coming from I did not say that Keith’s contributions were not good and yes he did HELP Paul Turner and Steve Simons in producing Rox Shox. And yes he did get into mountain biking a few years after Garry Fisher. All I said that it was Garry Fisher who went over to Japan and worked with Shimano. The rest is history and bikes are better for the likes of Keith Bontrager and Garry Fisher.

  • scrapiron5

    Really? The advent of Rock Shox wasn’t a big deal? Frames strong enough to not break off road? Keith’s contributions are huge.

  • David Bassett

    I do think this article goes round in circus (not such a bad thing) but it is quits contradictory. Correct Tullio Campagnolo did invent the QR. But as you said it was for speed. The bit Bontrager also highlights the more secure nature of the thru-axle: “[US firms] may move away from quick-release to reduce the problems with product liability… Incorrect use of QRs continues to be a problem in the States.” Well that is not just a problem in the states. The UCI saying you can only use components that are readily available for after market (In most cases a good thing) has come back to haunt the road racing. The bit about Keith Bontrager, arguably the godfather of modern mountain bike development is a bit misleading. He has done some good things but for those with memories of the sport of Cycling, Garry Fisher going to Japan and working with Shimano was by far the best thing that EVER happened in the development of cycling. Virtually all the improvements in BIKES has been a tickle down from MTB.