Featured Build: Mosaic RT-1D w/ Dura Ace 9170

Mark Strasnick on 13 Sep, 2017

Classically Modern


Shimano's Dura Ace 9170 Hydraulic Di2 Groupset has been something we have been looking forward to for a while now. Pushed back over 8 months from their initial projection (an eternity in Shimano time), it has been worth the wait. This is our first Mosaic with the build kit.  When debating between a C60, Bastion or Mosaic RT-1 this client decided it was well worth the wait for the best Boulder had to offer. He fell in love with the ride of Titanium.  No expense has been spared on this special build.

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Starting at the back of the bike, you can see the Ti cogs on the Dura Ace cassette as well as the new Shadow design of the 9100 series RD.  While prior generations of Dura Ace were limited to a 28t largest cog, the latest generation is designed to work up to a 30, allowing us to take advantage of a slightly larger gearing range.  Off the record, some frames we have been able to make a 32t function.  12mm Thru Axles are used front and rear.  

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On the other side you can see the new Dura Ace FREEZA rotors for additional cooling. Shimano sandwiches an aluminum rotor with stainless steel on both sides for consistent braking and the best heat dissipation possible.  Enve 3.4 wheels are laced to DT 240 hubs with the decals removed for a more subtle and cleaner look to the bike.


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One last look at the rear end before moving forward. Mosaic's subtle branding on the seat tube to denote the Model. Despite no rim brake caliper being mounted to the seat stay bridge, it was kept to ensure a solid rear end under hard efforts.


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When it comes to power meters, you can't beat the gold standard that is SRM. Their new Origin model uses carbon cranks that allow for three different crank lengths via a triangle shaped insert where the pedal mounts.  Precise, accurate and most of all reliable under the harshest of conditions, there is a reason that they are worth every penny.


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The other side of the SRM. If you look closely you can see the Kogel BB.  They are super smooth and carry a 2 year warranty which is unheard of for ceramic bearings. Also they are the only ones to be crazy enough to offer a BSA to 30mm spindle BB (as well as BB86 to 30mm), they are that good. Hard to miss the exceptional weld work on the BB of this Mosaic.


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Subtle Mosaic branding on the downtube. By utilizing double butting Mosaic is able to have a 44mm downtube and a create a frame that is very stiff while not being harsh. Ti is second to none when it comes to creating a smooth and stable frame. Also you can see the Arundel Mandible cages which are super light, but have a firm 'click' in and out and are almost impossible to eject a bottle from. They take years of abuse without issue, we love them.


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Clean routing of the brake and Di2 wires as well as some beautiful weld work and a shot of Chris King's limited edition Matte headset.


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Enve cockpits have been a favorite for years. Light, stiff, reliable, perfect ergonomics and at home on any build. As well as Supacaz tape. What is probably the most notable part of this picture is the 9170 lever. Somehow Shimano has managed to fit all of the Di2 parts and hydraulic master cylinder in a hood that is the same exact size as the regular Di2 and even mechanical rim brake hood size. Feel is excellent. The updated shift buttons are larger, harder to mistake and have a more positive click to them. In addition the hidden button on top of the hood is now programmable for shifting.


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Moving down to the front fork and axle. 160mm Rotor upfront. While disc brakes are an improvement over rim, especially on carbon wheels, one of the biggest benefits we have found is the stiffness gained by going to a thru axle vs. quick release. In and out of the saddle it is something you have to experience to appreciate.


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Front brake detail


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We dare say it will be near impossible to overheat this set up.


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When it comes to a supple and efficent ride Vittoria's Open Corsa G+ tires are our go to. Also the gum walls look oh so nice.


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Selle SMP saddles are a polarizing. Their traditional line of saddles were either a godsend or torture device, all depends on the rider you ask and what works for them. Recently they have expanded their line up with the T series. While we have found it to be a great option for many.  Saddle selection is unique from rider to rider. We spend a tremendous amount of time during the fitting to figure out from the hundreds of saddles we have access to, what will work the best.  In this case, black handmade Italian leather is a great compliment to this exceptional bike.


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Time to go ride!


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