The SL Domane uses Trek’s 500 series OCLV carbon, which is a grade below the 600-series used on the range topping SLR9 model that Trek’s pro tour riders speed across the cobbles of the spring classics on.
The Trek Domane SL 5 Disc is one of our Bike of the Year bikes for 2019. To read reviews of the other contenders and the categories tested across road, mountain and women’s bikes, visit our Bike of the Year hub page.
So while the carbon it’s built from might be a tad heavier than the SLR it does share the same frame technology as the SLR. That means Isospeed for both front and rear, and up front this comes in the form of a rocker-sup that replaces the top part of the headset.
This rocker allows the steerer tube to freely flex fore-and-aft with zero movement laterally, so while you get vibration damping and relief from jarring potholes and the like, the steering remains as precise as you’d have with a traditional head tube and headset design.
An IsoSpeed decoupler in the seat tube helps to smooth out bumpy surfacesDavid Caudery/Immediate Media
At the rear, the Isospeed design is a ‘decoupler’ in that it decouples the seat tube from the top tube using a sort of pivot rolling on smooth bushes (though Trek don’t like it when you call it that). The system allows the seat tube to react and flex with the forces acting on it from the road.
It’s a seriously clever design, and while the SLR model has an adjuster I’ve never found the SL version of Isospeed to be anything but spot-on for pretty much every road surface.
Since it debuted back in 2012, Isospeed equipped bikes have won Strade Bianchi, the Tour of Flanders and Paris-Roubaix, it’s fair to say that the tech has proved itself in the most demanding of races.
Another look at Trek’s Isospeed decouplerDavid Caudery/Immediate Media
Despite the Domane’s racing heritage, the SL 5’s ride position is very much in the endurance arena with my 58cm test bike sharing similar numbers to Cannondale’s Synapse (610mm stack, 393mm reach) with its 611mm stack and 380mm reach. Yes, it’s a little shorter, but not so much as to feel too upright or cramped.
The SL 5 in fact feels similar to the Synapse SE in many ways. On the plus side, the Domane is smooth and supremely stable over truly dreadful road surfaces, it also descends with a wonderful balance through fast corners and the confidence inspiring security of its impeccable grip means it goes downhill as well as Specialized’s Roubaix, especially through switchbacks and challenging corners and cambers.
Internally routed cablesDavid Caudery/Immediate Media
Sadly, like the Synapse SE, the wheel package takes the edge off the Domane when it comes to ascending. While I was impressed with the truly generous tyre clearance of the SL 5 (and the provision for mudguards front and rear), the alloy Affinity wheels and big 32c tyres simply kill any life or lively feeling when it comes to heading up.
Even with the wide gear range and bottom 1:1 gear of a 34-tooth chainring and 34-tooth sprocket, the SL 5 just didn’t feel as impressive as I’ve found with higher spec Domane’s in the past.
Trek’s commitment to a full Shimano groupset is good to see, and the 105 here works as doggedly well as I’ve come to expect. The only niggle I had was with the rather basic, non-Ice Tech brake rotors, which become a little too vocal after long periods of braking, though the power and feel still impresses.
The Comp VR-C handlebar is thickly wrappedDavid Caudery/Immediate Media
Trek’s Bontrager contact points are good with the narrow but comfortable Arvada saddle and VR-C bar both working well. The top-quality thick sticky rubberised bartape is a real quality touch and several grades better than you’ll find fitted as standard to most new bikes.
The all up weight of 9.63kg makes the SL 5 the heaviest bike in our Bike of the Year test category, only by a 100g or so, but if the SL 5 was running on a set of more modestly wide tyres (such as a 28c) then the disadvantage would be much, much less, as would setting these 32c tubeless-ready tyres and tubeless-ready wheels up as tubeless, as intended.
Tackle cobbles, towpaths, trails as well as tarmacDavid Caudery/Immediate Media
Like the Synapse SE, the SL 5’s generous rubber does mean its capable of far more than just tarmac — cobbles, unmetalled roads and even all but the most extreme gravel are within the SL 5’s grasp — we’d just prefer it to be a little less compromised on the climbs.