Mavic Enters the 650B Realm, sort of.

After years of development, Mavic, today, introduced a revolutionary mountain bike wheel system. With one technological breakthrough, Mavic’s CrossMaxSizer fitment system allows a rider to buy just one wheelset that can be adapted to fit all the mountain bikes they might own, whether they use 26”, 650b, or 29er wheels. The new wheelset is yet unnamed.

The new modular wheel system is built on a 26-inch Crossmax ST mountain bike wheel for the base structure. Testing revealed that this fundamental wheel system is strong and stiff enough to readily adapt to multiple sizes. “It’s remarkably clever, if I may say so myself,” Mavic PR person Zack Vestal said via press release. “We devised a system by which the rim outer diameter can actually be increased or decreased at the user’s discretion.
“On the one hand, we are getting a little sick of all these different size standards,” Vestal said. “I mean, can’t we decide on just one size for all the mountain bike wheels? But on the other hand, we wanted to offer something really different and satisfy these guys who can’t make up their bloody minds.”
With CrossMaxSizer technology, the mod-wheel converts from 26 inches to 650b, and from 650b to 29er.To increase the bead seat diameter for 650b usage, a snap-on expander ring fits into the UST tire bed and tightens into place with recessed setscrews. Just like the original tire bed, the CrossMaxSizer expander ring is fully UST compliant, with an airtight tire bed and 19mm inner width.
The Mod-wheel easily fits 29er bikes and tires with the addition of a second CrossMaxSizer expander ring, mounted on top of the first expander ring. “We found a light, flexible composite for the expander rings, so they really don’t add much weight,” offered Mavic MTB product tester Joaquin D. Trayle. “Plus, as you add CrossMaxSizer rings to achieve the 29er tire size, you’re adding rim depth. So there’s a nice aero benefit, too.”

The first schematic of the CrossMaxSizer

Mavic experimented with a removable insert to fit directly into the rim extrusion, but the extendable spokes and spacing presented an engineering challenge. It was a solid first step idea, similar in concept to what Keith Bontrager was doing in the early 1980s: cutting down and re-pinning 700c MA-40 road rims to make 26-inchers. But in the end, Vestal said, “trying to up-size for larger wheels, it was too complicated to be practical.”
At this time, Mavic has not announced a solution to fit the “yarder,” a 36-inch tire size popularized by a few builders at the North American Handbuilt Show. “At that size, we’d have to use the C29ssmax as our base structure, and we need to do more testing on this,” said Vestal.
On the other hand, Mavic is actively investigating the 24-inch wheel size. “Going forward, we think that ‘small’ might be the new ‘big,’” said Vestal. “I mean, how much more can we gain with going bigger all the time? We think 24s and maybe even the 20-inch wheel are the next frontiers in trail riding.”