Bike Review: Mosaic RT-1

Classic titanium with a family feel

Classic titanium with a family feel

Founded in 2009 by frame builder Aaron Barcheck, Mosaic Cycles is a small but growing bike brand located in Boulder, Colorado, that epitomizes the very relevant concepts of craftsmanship and passion. While much of the bike world has gone the way of big-box brands, there are still frame builders out there whipping together steeds that forgo what the current trends are.

With family members in tow, Aaron has assembled a team whose singular focus is building beautiful bikes that are not just spectacular to look at (Mosaic took Best Gravel Bike honors in 2017 at the North American Handmade Bicycle Show) but purposeful to ride. Both titanium and steel are the frame materials of choice, and with the recent acquisition of a paint booth, there is a dazzling array of paint schemes that are laid down by Aaron himself.



The RT-1 was designed to be Mosaic’s high-performance, race-ready machine that delivers the unique ride quality that titanium is famous for. It’s made from thin-walled, straight-gauge 3A/2.5V tubes that start with an oversized 44mm head tube that is machined in-house. To achieve their desired ride quality, each tube on the RT-1 was specifically chosen to suit a different part of the frame, with the downtube being the largest to help provide a more responsive feel.

Mosaic has a heavy focus on durability and designed the RT-1 to last through seasons of hard riding. The headset cups sit externally, and the bottom bracket is a threaded 68mm shell, giving riders confidence that their bearings won’t suffer a premature failure. The cables are routed externally, but riders have the option to choose internal routing for electronic drivetrains. Wrapping up the frame design is an Enve Road 2.0 carbon fiber fork.

Mosaic relies on a network of about 35 dealers located across the globe to help riders order their bikes. Each frameset has a lead time of six weeks. The RT-1 is available in a custom geometry and paint scheme with various templates for some added inspiration. While Mosaic offers a stock geometry, riders can dial in the fit to their
specifications when ordering, including different seat tube diameters and the option for an integrated mast. The base price for the RT-1 comes in at $5500. With the two-tone paint scheme on our test bike, the price jumps up to $6300.

THE PARTS        

Our test bike came with a full Shimano Dura-Ace 9100 mechanical drivetrain and Shimano Pro cockpit and seatpost custom-painted to match the frame’s finish. Mosaic capped off the custom build with a set of Enve SES 2.2 rims laced to turquoise Chris King hubs with a matching headset and bottom bracket cups. The finished product is a combination of refined attention to detail that is appreciated on just about every level of bike envy.

Bringing added elegance to the Mosaic, Chris King hubs are equally beautiful to look at.


Mosaic sent us a stock-geometry 56cm that is a true 56. The front triangle is big, with a long, straight top tube and steep seat tube angle. Up front the head tube is rather tall and does provide for a slightly taller stack height. We dialed in the reach and saddle height and found a good balance of comfort with a more aggressive ride position.

It was tough to actually take the RT-1 out and get it dirty; we might have spent just as much time cleaning the frame as we did actually riding it. Once the tires hit the tarmac, our test riders were surprised at just how effortlessly the RT-1 rolled. The frame was stiff and just as responsive as any high-end carbon frame that we have ridden in recent memory. Out of the saddle the rear triangle didn’t give us any unwanted flex and complemented the downtube stiffness for a snappy feel.

On rough sections of pavement the Mosaic boasted its vertical compliance and assured our test riders that it had that “classic titanium ride quality.” The RT-1 muted mild imperfections in the road easily and made longer days in the saddle more comfortable. We did all of our testing on 25c tires, but would go up to larger 28mm to get a little extra comfort for longer days in the saddle.

As usual, the Dura-Ace drivetrain provided flawless shifting and confidence-inspiring braking. Coming from two brands that are equally celebrated for their performance and quality, both the Enve rims and Chris King hubs delivered consistent performance and minimal drag.


There are plenty of matte black carbon superbikes out on the roads today, bikes that ride great and that we enjoy riding. Still, we put a lot of value on individuality, personality and nuance, and it’s bikes like the RT-1 that deliver all three in ample amounts. Not only that, but the bike is also so much more enjoyable to ride with each pedal stroke, reminding us of the storied legacy of what handbuilt frames bring to the table.

This colorful side of the sport does come with a heavier price tag, however. Riders who are seriously interested in the RT-1 won’t be concerned with price so much as getting a machine that will last them a lifetime and deliver a unique riding experience.


  • Stiff, lively and expensive
  • Oh, that vertical compliance
  • The paint quality is unreal


Price: $6300

Weight: 16.56 pounds

Sizes: Stock Custom


  • Helmet: Smith Overtake
  • Jersey: Shimano S-Phyre
  • Bibs: Shimano S-Phyre
  • Shoes: Northwave Flash Carbon
  • Socks: Volar Active Gaban Cane
  • Glasses: Smith PivLock

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