The Takeaway三九电影网 The Mosaic RS-1 is a stiff and beautifully balanced fully customized steel race bike that arrives at your door in six weeks.

  • Available with rim or disc brakes
  • Huge palette of colors and paint schemes from which to choose
  • Columbus Spirit HSS tube set has subtle shaping to enhance performance

    Price: $11,500 (as tested), $5,600 (frameset)
    Weight:
    三九电影网 16.8 lb. (as tested)

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    Boulder, Colorado–based Mosaic builds steel and titanium frames三九电影网 with custom geometry, tubing, and finish. Big deal, right? Builders like that are as common as houseflies.

    But Mosaic stands apart from other bespoke builders because of its promise to deliver a custom frame in just six weeks. In a space in which some builders can take a year or longer to do the same, six weeks for a fully customized bike is extremely short.

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    The RS-1 is steel, but Mosaic also offers titanium options.
    Matt Phillips

    That quick turnaround doesn’t translate to an inferior product. In fact, what you get is a carefully designed and beautifully constructed bike—as evidenced by the tiny and tidy welds—with a juicy finish courtesy of sibling brand Spectrum Paint and Powerworks, which offers such an extensive menu of finishes (the catalog is 40 pages), it could take six weeks just to decide on color and scheme alone.

    BKE
    The RS-1 is steel perfection.
    Trevor Raab

    三九电影网The RS-1, the only steel model the company offers, is now in its second generation. Like many US-based craft builders, Mosaic was using True Temper’s steel tube sets, but the from the bicycle market forced Mosaic to find a new source for steel tubing.

    Mosaic’s founder Aaron Barcheck stated that he tested several tube sets over a span of a couple years before going with Columbus’s Spirit HSS, “for its performance characteristics and aesthetic style. The HSS creates a ride that we’ve tried to achieve in our other models like the [titanium] RT-1, a bit on the stiffer side, snappy handling while still comfortable because of the material and thoughtful geometry approach. The tapered 1.5 head tube also adds to the new aesthetic for us while providing nice solid steering.”

    Despite the tubeset’s “very thin walls,” Barcheck is happy with HSS’s toughness, “[It] seems to be more durable than the True Temper S3 tube set, something we like too. With S3 you really had to take care of it not to rust or get dents because of the thin walls.”

    mosaic rs 1
    The bi-oval down tube ekes out extra stiffness.
    Matt Phillips

    Within Columbus’s large library of , Spirit HSS is one of the brand’s best. It’s based on the Spirit triple-butted tubeset, but while regular Spirit’s shapes are traditionally round, HSS utilizes more complex shapes to eke out more performance.

    Chris Merrill, president of Columbus-tubing importer Henry James Bicycles, explained, “The shape of the tube is designed to add some performance that cannot be achieved by a traditional round tube. For example, a bi-oval shaped down tube will add some torsional stability at the bottom bracket area, as well as at the head tube where it’s needed to provide stiffness to the frame.”

    三九电影网Let me allay any concerns of classic steel “modernized” with overwrought shaping—HSS’s shaping is subtle enough that from a few steps back, the bike looks like a crisp round-tubed steel bike. It’s only when you get up close that you see the octagonal top tube and that bi-oval down tube Merrill mentioned.

    mosaic rs 1
    A tapered head tube done right.
    Matt Phillips

    三九电影网The head tube deserves a mention as well because it is a tapered head tube that looks like it belongs on a steel frame. I’ve seen too many steel frames use straight 44mm head tubes to accommodate a tapered steerer fork. This results in a look I call “beer can with straws.” Steel frames should be graceful, and a fat ol’ head tube stuck to a couple of skinny tubes looks ungainly. The tapered head tube on the Mosaic is in proportion with the top and down tubes and flows cleanly into the fork’s crown. It looks good and it looks right. And when you’re spending $5,600 on a steel frame, everything should look good and right.

    三九电影网That’s not a misprint—this is a $5,600 frameset, which is a hell of a lot of money for a welded-steel frame. Included in that price is the option of a rim or flat-mount disc-brake design; mechanical, Shimano Di2, SRAM eTap, or Campagnolo EPS drivetrain accommodations; rider-specific tubing specification and geometry; an Enve fork, Chris King headset, and a finish in one of eight layouts and 35 stock colors.

    三九电影网You can find a number of great frames that cost less than a Mosaic RS-1. But in my opinion once complete bike prices rise above about $2,500 it becomes very difficult to argue you’re getting a profoundly superior bike by spending more money. They may be prettier, more aerodynamic, lighter, and have nicer parts and more exclusive brand names on the down tube—all things that can make them a more preferable and satisfying bike to ride—but once you spend more than about $2,500 on a bike, you’re buying something because it’s just what you want instead of only what you need.

    mosaic rs 1
    Crisp and lucious paint.
    Matt Phillips

    So sure, you can spend less on a very nice custom bike from a well-regarded builder or buy a hell of a carbon bike from one of the big brands for what you’d pay for a Mosaic RS-1. But what you won’t get is a Mosaic RS-1.

    三九电影网I can’t pretend to understand why some builders can take the same bits and pieces available to every other builder and somehow turn out something more magical. I suppose it’s the same as what would happen if you gave a random line cook and José Andrés the same ingredients and asked them both to make a meal. Some people have the touch.

    Based on how this RS-1 rides, Barcheck has the touch. The Spirit HSS tubing combined with the custom fit and geometry—which Barcheck nailed, by the way—made for a harmonious relationship. The most important elements of the bike came together to create a transcendent ride that I’ve experienced only a handful of times during my long career testing bikes.

    mosaic rs 1
    The RS-1 is the only steel bike in Mosaic’s line.
    Matt Phillips

    The RS-1 is rich and complex, bright and spirited, and it has bite. It’s far from the smoothest bike I’ve ever ridden (which is okay, because bikes like that are boring to me), but it’s compliant enough that I can ride it until I can’t anymore—without feeling worn down.

    三九电影网The frame is very crisp for a steel bike. When I put power into the bike, the response I feel is almost one-to-one power in to power out. I won’t pretend it’s carbon-bike stiff, but it’s stiff enough that it feels like a proper performance bike.

    三九电影网The handling is frictionless, intuitive. It initiates turns with a light-enough touch to feel sharp and reactive, but with enough feedback and resistance to damp the dartiness out of its motions. Its handling is composed at high speeds, lively at medium speeds, smooth at low speeds.

    Essentially, it fits, feels, moves, and handles exactly三九电影网 the way I want a bike to do those things. It feels natural and right to me. Again, I will not claim that this bike is better than or superior to something like a Cannondale CAAD13 105. Because I honestly can’t.

    But it is more preferable and more satisfying to ride than any other bike I’ve ridden so far. It is the bike I’ve always wanted. So, I bought it. After all the bikes I’ve ridden, I know that I’m not going to be a better or faster rider on this bike. I know that this Mosaic I spent money on—money I shouldn’t have—is not a better bike than many other bikes I could have bought for less money. But I also know when I’m on a bike that I love so much I can’t bear to let it go.

    三九电影网I expected this bike to be good. I hoped it would be great. But I didn’t expect it to be one of the finest road bikes I’ve ever ridden. It’s pleasing to look at, a pleasure to ride, and full of surprises. A custom bike this good in just six weeks? Yes, that’s a very big deal.


    —Build Specifications—

    Frame Columbus Spirit HSS
    Fork
    Enve Road Rim Brake
    Shift/Brake Levers
    SRAM Force eTap AXS
    Derailleurs SRAM Force eTap AXS
    Crank SRAM Force AXS Power Meter 35/48
    Cassette SRAM Force XG1270 10-28
    Brakes SRAM Force
    Wheels Enve SES 3.4
    Tires Rene Herse Chinook Pass Extralight, 28mm
    Handlebar Enve Road Handlebar
    Stem Enve Road Stem
    Seatpost Enve Seatpost 300mm
    Saddle 三九电影网Selle Italia SLR Boost Kit Carbonio Superflow