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This was our fault. We’re too obsessed with numbers. I blame the media, which means I blame myself. I can’t review a bike unless I’ve backed it up with a seat angle or a leverage rate curve. I was the same in my retail days. I’d explain the ways a customer’s ride would improve thanks to a bike’s numbers. But one number never sat right with me. The 15-millimeter axle went against everything I believed about round components: Bigger is better. As we know, the 31.8mm clamp diameter made our handlebars stronger and lighter. The 20mm axle could have done the same had we given it more time. RockShox was ready to make that happen. We just didn’t want them to.

“I had countless charts and graphs and data I could map together and say, ‘Look, it’s 50 grams lighter if you go 20×110,’” remembers RockShox VP of Product, Sander Rigney, who was a product manager at the time. “But it just kind of didn’t matter.”

We know how this story ends. 15mm wins. But years before that even existed, Rigney remembers stumping for 20×110. The industry had already agreed that 20×110 had a place on dual-crown forks, and Marzocchi had released a number of aggressive single crown thru-axle forks, but RockShox didn’t see it ending there. In 2000, they introduced the Psylo. It was a trail fork, not a ‘freeride’ fork, but it was available with the stepped 20mm Tullio axle, with its slide-away thumb lever and QR clamping dropouts. And it wasn’t great.

“Tullio was super problematic from a manufacturing standpoint,” admits Rigney. “It added a bunch of cost, and if you didn’t have the right tension, you could strip out the casting.” It was one of the last new products that then-struggling RockShox released before they were acquired by SRAM in 2002, which Rigney saw as a mandate to turn things around.

“We had some contacts at Honda’s HRC race division in California, and we had a couple sessions with them, picking their brain about how they do design.” This was around when Honda came out of nowhere with its high-pivot gearbox downhill bikes that, over three seasons, won a NORBA title and a World Cup title and then disappeared. One topic covered in those sessions was steering precision. Honda’s no-holds-barred design inspired RockShox to bring thru axles to their entire lineup, from DH to XC. “We took what was the industry standard—20×110 and we asked, ‘How do we develop the best system?’”

They introduced the Maxle, which needed no pinch bolts and no tools. It was featured on the trail-focused Reba and the all-mountain-focused Pike, which were the first products RockShox released under SRAM’s ownership. It was a familiar, easy-to-use, lightweight system that RockShox expected would eventually carry over to shorter-travel platforms. Cross-country had just begun to accept the added weight that came with
29-inch wheels and disc brakes. Thru-axles seemed like a reasonable next step, but the bike manufacturers who buy from RockShox didn’t see it that way. “Universally, brands were looking at us like we were crazy to push thru-axles onto 100 and 120mm forks,” Rigney says. “So at the last possible minute, I blinked and made the decision to switch to quick release. I took a lot of heat from a lot of people inside for not pushing it.”

But that was in 2004, and the market just wasn’t ready. Then, the sport started to change. Trail bikes were getting more travel, riders were getting more aggressive, and mountain bike videos were getting more rap metal. So, in 2008, RockShox committed, bringing 20×110 axles to more of their lineup. They introduced the Revelation and put a thru-axle on the Tora. One even showed up on the lower-priced Recon.

Talking to Rigney about this period, I could sense the hope and frustration behind these decisions. “It was time for us to show where our heart was and push on this. But after a year, it was not having the uptake that we hoped. In part because we had these lighter thru-axle forks, but there weren’t lighter hubs. The rest of the components hadn’t caught up. About that time we start hearing rumblings of, ‘Hey, have you heard about this
other thing?’”

At the last possible minute, I blinked and made the decision to switch to quick release. I took a lot of heat from a lot of people inside for not pushing it.

The 15×100 axle was a joint project between Shimano and Fox. This was before Eagle 1×12, or even 1×11, so Shimano was still on top in drivetrains. And it was before Fox had any entry-level forks to speak of. 15×100 felt premium.

But RockShox had allies at Mavic, who were also firm believers in 20×110, and they teamed up to make it better. “Their hotshot race wheel was the Crossmax SLR, and they went so far as to make a prototype in 20×110.” Rigney gets visibly excited remembering this wheel, one of which he still has. “I shouldn’t tell them, but it’s on my cargo bike that I ride around town. It proves to be an awesome wheel. We had that magic super-light offering. We could do it.”

But there was still resistance in the OEM market. With 15×100 becoming more established, it would mean brands would have to source and stock front wheels of two different standards, while leaving consumers and retailers with confusing, difficult choices. “Pretty quickly, within one selling cycle, we realized that 20×110 was not going to be the preferred standard going forward. So, we just decided we’d make the best 15×100 axle that could be made.”

The Maxle got lighter and abandoned its two-sided adjustment. Later, based on lessons RockShox learned developing the upside-down RS-1 fork, they introduced larger-diameter Torque Caps to improve the hub-fork connection and regain much of the stiffness lost in the 15mm compromise, though the concept has not gained wide acceptance. Then, Boost spacing widened the 15mm axle to 110, but in a more useful way than 20mm had by moving the rotor further outboard and spreading
out the hub flanges.

Although the 15mm axle standard has improved significantly, it’s still haunting that we would have been better off if the 20×110 axle had won. But Sander Rigney has made peace with it.

“We could have continued to fight this battle of 20×110 vs 15×100 and make riders question which one’s better. But, bigger picture, we’re better off introducing more riders to thru-axles. So let’s bury our pride for a little bit. Let’s put aside what we know to be the technical benefits to 20×110 and just accept that, in the end, it’s better for the market if we push forward around one consolidated standard.”