One on One with the Mosaic GS1 Disc All-Road

Remember this one? From NAHBS? It was one of my favorites in the show. Everything about it just looked right. First impressions are everything you see and these days, with the whole bigger is better mentality about tire clearances, it was nice to see something embrace a modest tire so elegantly.

Mosaic‘s GS1 disc all-road bike is a custom steel or titanium frameset, offered by the Colorado-based frame builders.

Let me reiterate that: this is not a production model with stock sizing. It’s made with 100% custom geometry. A custom geometry ensures this bike will fit you like a tailored suit.

The GS1 is a road bike with disc brakes and room for around a 38mm tire. It has a road bottom-bracket drop (72.5mm) and a slightly slacker head tube than your average road frame (72.5º). Side note: I like how those two numbers match up so perfectly. The 420mm stays and 1033.5mm wheelbase can be best interpreted as smooth sailin’ down your favorite road, be it dirt or sealed.

Mosaic GS1 Disc All-Road

Frame and Feel:

The most elegant detail on this bike, by far is the rear triangle, particularly the seat stays. They bend carefully around the tire, giving just enough clearance to make it look like the frame is suggesting the tire size, not opening itself to whatever you can cram in there. Moves like this show confidence in the builder and a very specific visual language about what this bike’s intent is.

Mosaic GS1 Disc All-Road

No, you can’t fit RockNRoad tires on it, no you can’t fit big knobbies either. But you can fit a supple, smooth rolling tire like the Barlow Pass or as it came spec’d on this build, the Clement XPlor MSO. If you need a bigger tire than either of those, then it’s strictly preferential, or the terrain is entering a different realm. Personally, I don’t view this bike as a back-country explorer, more of a road bike with a little extra cushion for when the washboard roads get washed out. Had I not just got my Firefly in the mail, I would have ridden this at Grinduro.

Because it’s steel, there’s already a good amount of vibration dampening going on and because it’s True Temper S3 tubing, it’s lightweight and stiff where it counts. The ride quality of S3 is unmatched, in my opinion. The tear-drop top tube and oversized downtube are reminiscent of an old Eddy Merckx MXL, yet the butting and thicknesses of these tubes are much more advanced than what Columbus was producing at the time.

Mosaic GS1 Disc All-Road

This thing ain’t a tank like the old MXLs were. It weighs in at 20lbs on the dot for the size 58cm!

With steel comes a few responsibilities. First: Frame Saver it! If you ride it in the rain, make sure it’s allowed to drain. With S3, you don’t exactly want to throw it in a bike pile. It’s a thin tubeset but you don’t have to baby it either. If you get to a nice, fast dirt descent, open it up! Let me tell you, as you’re descending that service road, the sounds of rocks pinging the downtube and stays get a little unnerving. Yet at the end of my ride, not a chip was found in the beautiful blue, wet paint job.

Mosaic GS1 Disc All-Road

The 44mm head tube has a nice and elegant machined shape.

Mosaic GS1 Disc All-Road

There’s a threaded bottom bracket, internal rear brake routing, down-tube routed shifter cabling, rack mounts and fender mounts. The GS1 has it all.

Mosaic GS1 Disc All-Road

These days, something like the lack of thru-axles might seem like a missed opportunity, yet on a bike with such sexy, confident detailing, the quick releases compliment it as much visually as they do functionally. Personally, I’ve found QR with disc brakes to be concerning on frames with more compliance. Sometimes you get an annoying disc and brake pad rub when out of the saddle (my Indy Fab does this a lot) yet with the tubing spec and frame engineering, it’s not an issue on the GS1.

Mosaic GS1 Disc All-Road

Build Notes:

Woah! Ultegra. Woah! A double. That’s nice. It even has a brazed-on front derailleur hanger! Like I said, my interpretation of this bike is not for back-country, excursion style riding. Personally, I gravitate towards 1x setups on my own rigs but that’s because the kind of riding I do on my all-road bikes are similar to what I’ll do on my XC MTB rig and I like the simplicity of a 1x setup with a large cluster on the back.

The GS1 however made me embrace not only the functionally of a road double, but really begin to miss riding with a front derailleur in certain applications. I’d also like to just note that the hydro Ultegra feels great. Ergonomics, modulation, everything feels amazing.

Mosaic GS1 Disc All-Road

PRO is normally not the way I go, but I have to admit, the Shimano PRO lineup makes some pretty trick components. The saddle, even though it’s not the best looking profile out there is incredibly comfortable, the bars have a great feel to them as well but I cannot for the life of me get behind the stem. It slips when you hit big bumps, regardless of torque and it seems too form-driven. Just give me four bolts and call it a day, guys…

Mosaic GS1 Disc All-Road

Wheels are a no-brainer. Disc R45 to HED Belgiums. Done.

Mosaic GS1 Disc All-Road

Now onto the question I got asked the most: the fork. These are from Colorado, under the name Ethic. They’re the in-house fork for the brand Alchemy. They’re plenty stiff, plenty good lookin and offer plenty of clearance without going full-on disc cross. With a 45mm offset, it matches quiet well with the 72.5º head tube. Painted to match, too!

Mosaic GS1 Disc All-Road

Take Me Away with the Take-Away:

The GS1 is a roadie’s dirtbike. It’s not so overblown with clearances that it looks like a drop bar hard tail. It dances with you on the climbs and rails the descents. It’s got classic panache with a confidence-inspiring build kit. The paint, geometry, silhouette scream road, road, road! in an era that is shouting dirt, dirt, dirt. Yet it can eat its share of the sketchy stuff too.

With a custom geometry, custom paint and built to suit your needs, the GS1 is a worthy bike for consideration.

Make it Rain:

Frameset (Custom Geo Frame, Fork, King headset, choice of paint) – $3,700.00
Estimated full build cost for current baller setup – $6,700.00

Turnover on steel Mosaics is approximately 6-8 weeks, see your Mosaic dealer for more details or give them a shout.

22 responses to “One on One with the Mosaic GS1 Disc All-Road”

  1. Max Dilthey says:

    That fork makes this bike look like it’s constantly lunging forwards… I love it. Any news on whether these are going to go to production?

  2. Naz Hamid says:

    I love the work that Mosaic puts out, but it’s their steel bikes that really shine to me for whatever reason — likely because the paint gives them more character over the standard unpainted ti. And agreed on that fork — reminiscent of the old Alpha-Q CX20s, one of the best!

  3. boomforeal says:

    the frame has full fender and rack mounts, but the fork seems to have none? odd spec

    (edit: sorry, i’ve got fender mounts on the brain right now, even more so than usual)

  4. Kerry Nordstrom says:

    How close does the leverage arm on the front derailleur get to the rear tire?

  5. Richard Ellis says:

    X’Plor MSO in a 36mm? Anyone know availability?

    • GT says:

      Supposedly, they’re tubeless ready and available in Nov.

      • Richard Ellis says:

        Great, thanks for the info! I run the 32mm MSO, but would like a bit more width (though can’t fit the 40).

  6. Jimmy says:

    I always ride near their shop in hopes of seeing some of their bikes rolling in/out. Gotta fight the urge to just press my nose up against the window sometimes

  7. D0rk says:

    She’s pretty, for sure. Love the dropouts and the curvy stays.

  8. Ham Sandwich says:

    this is the allroadiest all road that has all roaded since all road even began allroading. #allroad

  9. Chris Valente says:

    Let’s all just take a moment and pay some respect to that head tube badge. Sick bike.

  10. Yes. I’ve got my big knobby CX bike. And I’ve got my skinny-ass road bike which I want to replace with a slightly chubby all-road bike. Kind of CX-styled (smaller tires), with a more road geometry. This is another example to file away…

  11. Tinj says:

    NICE. “more of a road bike with a little extra cushion for when the washboard roads get washed out”. Would probably lean towards a less supple tube-set but, this thing is nearly perfect. Those seat stays!

  12. Froste says:

    Those antirubthingies on the cables are slick. What are they? Do they work?

  13. Kane says:

    The seat stays remind my of a Speedvagen. Actually this whole thing is quite similar to the SV Rugged road… Awesome.

  14. AaronBenjamin says:

    The best details on this bike center on the rear brake line routing. Those simple cable holders on the stay and the internal downtube routing are genius.

  15. Joel Augustine says:

    Any close up pictures of the top of the bike looking down? Curious of the tear drop top tube looks from above. In some of the pictures it looks round and others tear drop. But overall the bike looks great!