This is what happens when a titanium builder with nothing left to prove decides to reset the bar anyway.
Turns out, that’s exactly what Aaron Barcheck intended when he sat down to design Mosaic’s next-gen road platform from scratch.
^Mosaic’s clean-sheet RT-Zero.
According to Aaron (Mosaic's founder), RT-Zero is a full material rethink: an open challenge to what titanium road bikes can feel like in 2025. And for Mosaic, whose name has been a benchmark of consistency for over a decade, that kind of shift was needed. So we sat down with Aaron to learn more.
“When you create something that works so well, the problem is that eventually that thing becomes the standard, and you need to set the benchmark again...that’s why we built RT-Zero.”
What is the Zero Ops Project?
The RT-Zero story starts in 2021, when Aaron was sketching ways to integrate a carbon mast into a titanium frame. A mold was cut that same year, but immediately shelved as day-to-day work took priority. “Demand was picking up and the reality of a small team is that if two or three of us spend a few hours a day on development, that’s half the workforce. R&D work is enormously resource intensive," says Aaron.
Flash forward to January 2025. Mosaic was in the middle of a broader conversation about product identity, market drift, and the kind of bikes they actually wanted to build. “...we finally had the capacity, and MADE gave us the deadline. That’s when Zero Ops became real.”
^RT-Zero prototyping
The Zero Ops mandate: build the next generation Mosaic road platform without constraint. No pressure to reuse standard tubeset, no obligation to play by the rules that made their existing lineup successful.
“We wanted to take the best of Mosaic, and see what was possible.”
–Aaron Barcheck
What the RT-Zero Means for a Rider
On paper, the RT-Zero is a titanium road bike with some carbon enhancement. But that completely undersells what’s going on here. The D-shaped carbon seat tube adds torsional stiffness and helps tune vertical compliance. But it also drops weight (Zero is 16lbs), visually modernizes the silhouette, and pushes the aesthetic in a direction Mosaic hadn’t fully embraced until now.
C: “Tell us about the titanium-carbon junction. That can be really complex.”
A: “The real technical challenge was mating the D-shaped carbon mast into the titanium frame. We had to design custom tooling and fixtures to hold that pressure in place so we could weld the frame around it with Mosaic’s methods.”
"Most builders will just use a round carbon tube because it’s easier. You just plug it into a collar and glue it in. We wanted something unique to Mosaic with a sleeker profile. That meant creating a D-shaped sleeve at the collar and a matching plug at the bottom bracket. What you end up with is this really elegant cluster where the topper line, the collar, and the plug all trace together cleanly, and it still carries the TIG welds that define a Mosaic.”
Aaron didn’t want to jump on 3D-printing either. “We really wanted to see how far we could take it using traditional methods,” he told me. All the joining interfaces between carbon and titanium are machined and welded in-house. “Even the bits that look printed. That was part of the challenge.”
C: “Most brands are chasing 3D-printed solutions right now. What made you resist that trend?”
A: “We’ve definitely been pressured to 3D print… companies call us up and say, ‘why don’t you just use this, it’s way better.’ Instead we asked, could we do all the same things people are printing, but do them the Mosaic way? It’s actually that simple…we have a specific approach and that’s what makes our product special….it’s why you see CNC head tubes, CNC dropouts, and a CNC seatstay collar. No printed titanium.
...and it wasn’t just the machining. Mosaic kept the entire Zero Ops process under their own roof. “We could have outsourced the industrial design, the prototyping, even the typography and logo work. But that’s not who we are. These things were all done by people in our immediate orbit. It’s part of what makes the bike special.”
"We wanted ultimate control"
The result is a frame that holds together with the same hand-built DNA Mosaic is known for. But now it feels radically sharper, stiffer under load, and more precise in aggressive handling scenarios. So if you’re a rider coming from ultra-light carbon, the RT-Zero offers a new level of response without giving up the planted road feel that makes titanium special in the first place.
Why Zero Does (or Doesn’t) Belong in Your Quiver
The Zero won’t be your do-everything winter bike.
“We were chasing somebody that’s interested in a high-performance bike, someone that might consider a Dogma or a Tarmac. We’re not going to pretend we chased the aero story…but we most certainly chased the ride feel of a light, stiff, snappy race bike.”
Although we haven’t ridden the Zero ourselves (only 3 exist), this is believable. Aero gains make little to no impact for 99% of riders. Outside the wind tunnel it’s marketing speak, not something you’ll feel on a 3-hour session. RT-Zero is still titanium. At 16lbs it will ride with composure, but it’s not ultralight carbon layup. So this platform is for riders who want feel and fidelity, and something that will outlive trends.
^Zero in Shatter Camo
Zero vs. ITR
In Mosaic’s lineup, ITR is their long-running titanium road platform, so naturally we wanted to see where Zero slots in. Aaron contrasted the two: “the RT-Zero isn’t a replacement but a higher-strung sibling. ITR stays in the catalog as a more versatile road option, while RT-Zero is the sharper, stiffer, ‘pure road’ machine.”
C: How does RT-Zero ride different from ITR?
A: “It’s built on a platform similar to the ITR, so it will still clear a 35 mm road tire. The addition of the CNC dropouts and T47 shell probably added a bit of stiffness to the rear end compared to the ITR, but we tried to balance that so it wouldn’t get overly harsh. If you swap the stiff Partington wheels and small tires for something more compliant, you can make it a little softer without losing that snappy road feel. The carbon seatmast and topper also smooth out the little vibrations, so even with race wheels it feels exceptionally composed.”
C: Is this the new design direction for Mosaic?
A: “The RT-Zero opened the door to things we had wanted to try for years. Integrated routing, new CNC interfaces, the carbon mast system. We proved that those ideas can be executed with our methods and tolerances. That knowledge definitely informs how we design and build everything that comes next.”
C: Will we see this tech make its way into other models?
A: “RT-Zero still sits alongside the RT-1 and the rest of our road lineup. But some of the pieces we R&D’d for Zero Ops will eventually trickle down into other models once they’re commercially viable…the intent is always to try new ideas on the halo project then bring them into the standard models once they’re realistic.”
What You Need to Know
Only 25 RT-Zero frames will be made in the initial run. AC has 3 reserved as of this writing. Each includes:
- Custom-butted titanium frame
- 16lb for a raw, 56 (Shimano full build)
- ENVE In-Route fork
- ENVE one-piece bar/stem
- D-shaped carbon seat tube and Mosaic carbon topper
- T47 bottom bracket shell
- Full internal routing
- Fit up to a 35 road tire
- MSRP: $11,000 in Shadow Titanium, $12,500 in all painted finishes
C: Is the 25 units real, or is that marketing?
A: “For us, it’s real. We’re a small company and this is a big endeavor. Limiting it to 25 keeps the promises tight. We order the machined and carbon parts against that number, and it lets us deliver the bikes when we say we will.”
While production is limited, we’re working closely with Mosaic to prioritize Above Category builds. We have three slots left, please reach out if you’d like to reserve one, or learn more about RT-Zero.
Our Take
We’ve worked with Mosaic for over a decade. We’ve seen their consistency, their craft, and their willingness to evolve. But this is really something new. One of the most respected builders in the game has decided to break their own pattern and see what is possible.
The result is one of the most thoughtful, well-built, quietly radical titanium bikes we’ve ever seen.
If you’re interested in seeing it up close (or want to start a conversation about whether it’s right for you) get in touch. Julius or Chad can walk you through it.
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