'Not a concept bike' – Mosaic rolls out a 32-inch gravel bike that’s 'not an experiment'

Mosaic GT-1 i55 32 — (Image credit: Mosaic Cycles)

Yesterday, we wrote that the supporting ecosystem around 32-inch wheels is beginning to catch up. Today, there’s another fairly significant piece to add to the puzzle: an actual bike you can order.

Mosaic has unveiled the GT i55 32, a handmade titanium gravel bike designed around 32-inch wheels. And the Boulder, Colorado, brand is making its intentions pretty clear: this is, in its words, "not a concept bike."

Thirty-two-inch wheels are quickly becoming the bike industry's biggest new trend. We saw a host of bikes, wheels and tyres at Sea Otter, followed by perhaps the highest-profile example yet at Unbound Gravel, where defending champion Cam Jones and ultra-endurance racer Robin Gemperle raced Scott’s RC Gravel 32-inch prototype. But Scott made it clear that its bike was a "pure prototype," stating that it "will never be released on the market."

More than simply squeezing bigger wheels into a gravel bike

Larger wheels bring some compelling theoretical advantages. Compared with a 700c wheel running an equivalent-width tyre, the shallower angle of attack should help it roll over rocks, holes and generally rough terrain more easily, while the larger wheel size is also claimed to carry momentum more efficiently.

But there are compromises. Bigger wheels increase stack and wheelbase, stretch chainstays and can create toe-overlap headaches – particularly as frame sizes get smaller. They’re concerns Cycling Weekly has looked at in depth in previous coverage.

"...A new wheel standard only matters if its benefits aren’t limited to the tallest riders in the field," Mosaic states and tackled the aforementioned limitation as "an engineering problem rather than an unavoidable consequence of the wheel size."

For starters, the brand's designers decided to design an entirely new platform from teh groun up rather than modifying one of its existing gravel bikes.

The frame uses a bent seat tube and relatively compact 440-445mm chainstays to tuck the rear wheel beneath the rider. A 3D-printed titanium yoke creates clearance for tyres up to 55mm (2.2"), while still accommodating a standard gravel chainline and chainrings up to 46 teeth.

The axle standards do move into mountain bike territory, with a 148x12mm rear and 110x15mm front.

And then there’s the fork

Mosaic says one of its biggest headaches was finding a fork that would allow the geometry it wanted without pushing the front of the bike too high.

So it made its own.

The result is a new 32-inch gravel fork under Mosaic’s new Zero Components name, with a 445mm axle-to-crown measurement and 60mm offset. The former is intended to keep the front end down, while the latter helps Mosaic achieve its desired steering geometry while creating more toe clearance.

Mosaic says the combination of its shorter fork, increased offset, compact rear triangle and offset seat tube helps make the platform work across a wider range of rider sizes.

And because these bikes are being offered through Mosaic’s custom programme, geometry can also be tailored to the individual rider.

You can actually buy this one

Mosaic is rolling out the GT-1 i55 32 in two initial versions:

Fully integrated: The high-end option gets fully internal brake routing, a T47 bottom bracket and a choice of Mosaic’s standard paint layouts, with pricing starting at $8,250.
Semi-integrated: The second option offers semi-integrated brake routing via Cane Creek HCR, a T68 bottom bracket and Mosaic’s Titanium Ghost finish, and starts at $5,000.

Both come with rider-specific custom geometry.

More information can be found at mosaiccycles.com.

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Cycling Weekly's North American Editor, Anne-Marije Rook is old school. She holds a degree in journalism and started out as a newspaper reporter — in print! She can even be seen bringing a pen and notepad to the press conference.

Originally from the Netherlands, she grew up a bike commuter and didn't find bike racing until her early twenties when living in Seattle, Washington. Strengthened by the many miles spent darting around Seattle's hilly streets on a steel single speed, Rook's progression in the sport was a quick one. As she competed at the elite level, her journalism career followed, and soon, she became a full-time cycling journalist. She's now been a journalist for two decades, including 14 years in cycling.