Plenty of mountain bike frames feature flip chips that allow riders to change their wheel size without compromising the geometry or the ride quality. But flip chips aren’t the only solution. Two innovative designs for swapping wheels recently caught our attention, and one in particular has the potential to save riders from buying a new fork.
Cotic Double Decker Dropouts
The 2026 Cotic BFe hardtail, announced earlier this week, features the brand’s unique Double Decker Dropouts. In a release, the brand notes, “this allows you to run either a full 29er setup, or a mixed wheelsize Mullet option without affecting the geometry at all.”
Previously, Cotic offered dedicated 27.5 and 29er versions of the BFe hardtail. The 2026 BFe fits a rear 29er tire up to 2.6″ wide, and there’s clearance for up to 2.8″ tires on a 27.5″ wheel.
While the Cotic dropouts feature two dedicated axle holes, other brands like Focus have utilized an oval-shaped opening, as seen here on the 2020 Focus SAM2. A hardware “chip” is used to adjust the axle position to accommodate different wheel sizes.
Inverted Push Industries fork fits 27.5 or 29 wheels
Back in July, I wrote an article titled “Many of the latest MTB forks are 29er only, leaving buyers with fewer 27.5 options,” and several readers commented to express their disappointment and frustration. However, Push Industries has an innovative design that promises high-end performance no matter which wheel size you’re running up front.
When the Push Nine.One inverted fork was announced in early 2024, the Colorado-based suspension company introduced the concept of bolt-on axle lugs. The swappable lugs are marketed as a way to “easily switch between axle offsets as well as wheel sizes without purchasing a new fork.”
Converting a bike with 27.5″ wheels to mixed wheels is generally pretty straightforward, though buyers will need to purchase a new 29er fork and wheel. With the Nine.One fork, buyers don’t need a new fork, just new axle lugs.
The Push Nine.One is a premium inverted fork offering 140-170mm of internally adjustable suspension travel, and has a premium price tag to match: $2,250. Picking up a second set of lugs to run a second wheel size runs another $450. Even the base price is higher than the Fox Podium inverted fork, though for 27.5 bike owners, the Podium isn’t an option since it’s designed to fit 29er wheels only.
Seeing the Push bolt-on axle lugs got me wondering: With a custom lug, would it be possible to fit a 32″ wheel on the Nine.One fork? I posted my question on the brand’s Instagram page.
“How about 40″ mode 🤯,” came the reply. “No 32″ mode in the works at the moment.”
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