Mosaic GT i55: 55mm Tires, Shorter Chainstays, and a $5K Entry Point
Mosaic's GT i55 gravel platform clears 55mm tires with a 3D-printed titanium yoke and shorter chainstays. Framesets start at $5,000.
Mosaic just rebuilt its gravel platform from the ground up, and the headline number is 55mm tire clearance. That's 700c x 2.2" territory — enough rubber to blur the line between gravel bike and light touring rig. But the engineering underneath that number is what makes this interesting.
The rear triangle is completely new. Chainstays actually got shorter — down from 435mm to 430mm — while simultaneously making room for those massive tires. That's not a trivial trick. The solution: a 3D-printed titanium yoke at the seatstay junction, paired with an offset seat tube. It's Mosaic's first additive-manufactured component, and it exists because conventional tube manipulation couldn't solve the geometry puzzle. The yoke clears chainrings from 38 to 50 teeth, so you're not locked into a specific drivetrain choice.
Mosaic also designed its own fork rather than spec an off-the-shelf option. The 415mm axle-to-crown measurement is suspension-corrected, meaning you can swap in a RockShox Rudy or similar without wrecking the geometry. Fully internal brake routing. Fender mounts. It's a gravel fork built for actual gravel conditions, including the kind of mud that's ended more than a few Unbound dreams.
The GT-1 i55 frameset starts at $8,250 with an ENVE In-Route stem and post included; the GT-2 i55 starts at $5,000 with semi-integrated routing through a Cane Creek HCR cockpit. Both use T47 bottom brackets and UDH dropouts. Batch Built versions — standard sizing, faster delivery — will hit later this fall at $7,500 and $4,250 respectively. That's still a significant investment for a frameset, and the custom Made to Order option only goes up from there.
The real question is whether 55mm clearance changes your riding or just your spec sheet. If you're already running 45mm tires and feeling limited on chunky gravel or mixed-surface routes, this opens up real capability. If you're mostly on hard-packed fire roads, you're paying for headroom you may never use. Mosaic built this for riders who've been asking for more — the ones pushing into rougher terrain where tire volume is the limiting factor. For everyone else, the previous platform probably still fits the job.
