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April 4, 2016 – Trek’s original Domane has been the most successful road bike in the Wisconsin brand’s line since its launch in 2012. Its influence is hard to overstate. The bike has provided the brand’s biggest wins, Flanders and Roubaix, influenced the design of the new Madone, its ‘cross bikes and its mountain bikes, allowed Trek to unshackle the Madone from its jack-of-all trades responsibilities, and set a new performance bar for endurance bikes.
Trek would be excused for simply doing a safe update. Make it a bit lighter, add some aero, shuffle the tube shapes a bit. Trek did not play it safe. Instead it doubled down on the IsoSpeed technology that made the original Domane a standout.
The rear IsoSpeed decoupler, a pivot point at the seat cluster that allows the seat tube to flex vertically irrespective of the the rest of the frame, is the breakthrough that allowed Trek to mate a buttery smooth rear end to an incredibly stiff power platform. The new Domane now has an adjustable rear IsoSpeed decoupler – that’s right, adjustable.
Loosen the lower water bottle bolt on the seat tube and a slider on the seat tube itself can be moved up and down. Raise it and the seat tube’s leverage decreases, stiffening the ride. Lower it and the lever arm increases, allowing more flex, 14-percent more than the original Domane. Overall, the bike can be made 31-percent more compliant in the saddle by dropping the slider from the upper setting to the lower setting.
The adjustability serves two purposes, one it allows riders of different sizes and weights to experience the same vertical deflection. For the first time a taller or heavier rider doesn’t have to ride a frame that flexes significantly more than a smaller rider experiences. Secondly, your bike can now be adjusted for different terrain. Long day over rough road? Slide it down. Ninety-minute supersonic club ride? Stiffen it up.
Watch this video to see exactly how Trek’s new adjustable IsoSpeed works.
The only quibble riders had with the original Domane was a bit on an unbalanced feel over rough terrain. The front end, as comfortable as it was, simply could not match the silky smooth rear end. Trek has now given the new Domane an IsoSpeed Front. The steer tube itself can travel front to back, with a pivot set in the top of the head tube. Where the rear IsoSpeed separates compliance from power transfer, the Front IsoSpeed separates compliance from the lateral stiffness needed for precise handling. Front IsoSpeed is not adjustable and the amount of compliance it delivers is heavily dependent on the length of stem. A 90mm stem is 5-percent more compliant than the original bike and a 120mm stem is 10-percent more compliant.
These two innovations are the standout features, but not all the bike brings to the table. A new Bontrager IsoCore carbon bar uses a rubber compound within the layup in a process that may be similar to the vicsoelastic layers used by Bianchi in its Countervail frames. Bontrager claims a 20-percent increase in compliance at the hoods versus standard Bontrager carbon bars. To help all of this comfort technology shine Trek has upped the bike’s tire clearance significantly – 28mm on the rim brake version and 32mm on the disc brake version. In our testing a 30mm still easily fits on the rim brake bike, thanks in part to the direct mount brakes. Like the new Madone, the Domane has a down tube compartment to hide Di2 batteries and hardware, but hidden under the water bottle for a clean look.
Trek delivers the bike in two fits, the tall and relaxed fit of its endurance geometry and the race inspired, aggressive Pro Endurance geometry Fabian Cancellara and the rest of the Trek/Segafredo team races. Our test bike was a 60cm Race Shop Limited with the Pro Endurance fit and a Project One paint job. It was built with Dura-Ace 9000 and Bontrager Aeolus 3 TLR carbon clinchers and Bontrager bits and pieces.
Of course, we instantly put the bike on the scale. Would all the hardware inherent in the IsoSpeed technology hurt on the scale? The short answer is, ‘No’. This 60cm turned a scant 15.5lbs on the scale. It seems Trek’s IsoSpeed has some gravity distortion technology as well.
The pure power transfer of the Domane remains – raw, unfiltered acceleration – amplified by the rear’s ability to remain planted and allow you to stay on the gas, no matter the road surface. These were things the original Domane already did, so the real question becomes the adjustable IsoSpeed rear. Gimmick or innovation? While it could be argued a smartly engineered static frame can deliver comparable compliance to the original Domane, no traditional bike can deliver the versatility of the Domane SLR. The difference between ‘high’ and ‘low’ settings on the bike is startling. The Domane SLR can transition from a 60min crit machine to a legitimate threat at many gravel or mixed surface events – the adjustable IsoSpeed is that effective.
Watch adjustable IsoSpeed in action with this bike mount footage.
The front IsoSpeed is a more subtle affair. At first blush, certainly on the tops, the difference is hard to discern, but out on the hoods over rough road, the comfort becomes apparent. Front IsoSpeed is very dependent on leverage, making a bigger difference with longer stems and bigger bars. We’re sure a system that delivered big comfort on the tops would be way too flexible at the hoods. Trek has walked a fine line here, and done it very well. Beyond the comfort in the hoods, front IsoSpeed creates incredible confidence handling rough terrain. The front wheel manages to stay in contact with the road surface as the fork moves front to back, but the incredibly stiff head tube keeps it pointed exactly where you want. But perhaps the biggest gauge of its success is even more subtle, the Domane SLR feels balanced over all terrain, a balance the original lacked on very poor surfaces.
What are our concerns? There is of course the question of long term durability. The technology of this bike is brand new and how will these moving parts – bearings, pivots and sliders – hold up over the lifespan of bike, which can be ten years or more? Knowing Trek’s dedication to testing and the maniacal lengths it goes to to induce failure in the lab, we imagine the Domane SLR will operate as intended for many, many years, but only time will tell. During our test, all of these parts operated flawlessly and silently – no knocking, banging or rattling was ever heard or felt.
The Domane SLR makes one thing very clear, something Trek has been knocking on the door of since 2012 and the original Domane. That knock got louder with the Emonda and almost broke the door’s hinges with the new Madone. The Domane SLR has broken the door to splinters. On the other side? Simply the most exciting and innovative brand in cycling – Trek. That is something no one would have predicted five years ago.
The Domane SLR is available from Trek’s Project One now.
The Domane SLR Race Shop Limited frame set we tested can be had for $3000
The Domane SLR 6 starts at $5000. The Domane SLR 6 Disc is $5500.
A the top of the range is the Domane SLR 9 with SRAM eTap for $11000.
For more information on the entire range hit trek.com.
Zipp have long been known for two things: aerodynamics and... Read more →