Tullio Campagnolo invented the quick-release skewer more than 80 years ago, and for all intents and purposes, the basic internal-cam design he pioneered has changed little since then. If anything, many modern skewers have actually gotten worse and it wasn't long ago that I called for all of the crappy ones to be banished from existence. Today, however, I think the time is fast approaching that we should consider getting rid of quick-release skewers entirely.
Thru-axles are well accepted in the mountain bike world, and for good reason. Compared with open dropouts and quick-release skewers, thru-axles are generally stiffer, safer and more precise. This translates to noticeably more predictable handling – even with rigid forks and hardtails – fewer accidents related to misuse, and more consistent wheel placement in the frame and fork.
So why aren't we using them on the road?
The argument against
Without question, tradition is a big deterrent. We've all been using quick-release skewers for so long that it's hard to imagine a road bike being built without them. Even with changing drivetrain standards, there are still decades of compatible hubs and wheels out there, lending gobs of freedom to selecting your gear.
Going along with that is the oft-repeated sentiment of, "Quick-release skewers work fine, so why change them?"
Another obstacle is the professional racing world, where races can be won or lost based on the speed of a wheel change. A top mechanic can get a rider back on the road in less than 15 seconds with little more than a flick of the wrist standing in the way of a fresh wheel.
There's also the weight argument. Quick-release setups can be exceptionally light, especially when some of the more exotic stuff is used. Open dropouts can also be made in feathery carbon fiber and there's less material required than with a thru-axle setup, too.
The argument for
I believe thru-axles will soon be widespread on the road. Here's why:
Yes, tradition is a powerful motivator and it's great that there are so many years' worth of compatible products out there. Truth be told, though, the bikes we're riding now are pretty far removed from what Eddy Merckx used back in the day. Recent years have demonstrated that the cycling industry won't hesitate to toss traditional equipment standards out the window if there's an engineering (or marketing) argument for something better.
Heck, 26-inch wheels have been the de facto standard in the mountain bike world since the Repack days but in just a couple of years they've been practically erased from the landscape.
Interestingly, for once the UCI may also actually be fueling the argument for technological change. Recent rulings have deemed it illegal for teams to file the safety tabs on riders' forks. As a result, mechanics can no longer pre-size their skewers to speed up a wheel change and we've already started seeing the consequences of that on the road.
Thru-axles as they stand now are generally slower to operate than quick-release skewers but even that's changing. Focus recently introduced a novel thru-axle design called RAT (Rapid Axle Technology) that could legitimately turn the tides. The system requires just a flick of the lever and a quarter turn to engage and disengage. Even better, the system retains its adjustment with repeated use so at least in theory, it's roughly on par with a lawyer tab-equipped quick-release system in terms of speed while also offering the benefits of more repeatable wheel position and increased stiffness and security.
Focus may not license the design to other companies, though. After all, Focus makes bikes, not components, so why would it want to give up its advantage? However, RAT is an undeniably slick design and its widespread adoption could go a long way towards lowering the barriers to acceptance. At the very least, Focus has already announced that RAT will be included on its upcoming disc brake-equipped road bikes so the wave is already building.
Finally, there's the issue of weight. Thru-axles may be bigger and bulkier but in reality, they're actually not much heavier at all. A current RockShox Maxle Lite front thru-axle skewer weighs 74g while a standard Mavic Ksyium front quick-release skewer is 52g. Meanwhile, a quick-release DT Swiss 240s Center Lock front hub weighs 126g but switching to the thru-axle fitment adds just 2g.
Admittedly, the disparity grows when you move toward the high-end: Tune's DC15 15mm thru-axle skewer weighs 40g but its hyperlight U20 front quick-release skewer is about 10g. Thru-axle dropouts also require more material. Paragon Machine Works' titanium rear quick-release dropouts are 60g per pair while the comparable thru-axle version is 91g.
Still, we're talking small numbers here, plus we're dealing with thru-axle components that were designed with mountain bike stresses in mind – meaning the numbers are likely to come down moving forward. If thru-axles do come to the road market en masse, it's a safe bet that bicycle (and wheel) manufacturers will want to introduce yet another standard to go with it in order to bring down the weight and size.
Then there's the influence of disc brakes. While there's an argument to be made for thru-axles on rim brake-equipped road bikes, it's certainly more compelling when discs are involved. Compared to open dropouts, thru-axle setups are better equipped to handle the asymmetrical torque of disc brakes, plus it's virtually impossible to eject a wheel from a closed dropout under hard braking. Moving forward, it seems unlikely that bike companies will want to continue with two wholly disparate development platforms.
Finally, given the litigious nature of the US retail economy, the final nail in the coffin could very well be the increased safety factor of thru-axles. They're simply harder to install incorrectly than traditional quick-release skewers, plus the wheels are less likely to catastrophically fall out even when they are.
We're riding our bikes harder and faster than ever, and asking them to do more. Likewise, bike manufacturers continue to push the engineering envelope. Tullio Campagnolo may have made a monumental contribution to the cycling world eight decades ago but even sacred cows eventually have to be put out to pasture.
What's your take on the argument? Chime in below.