Trek Domane SLR

There are few endurance bikes as comfortable as the new Trek Domane SLR. A host of changes ensures the new bike is incredibly smooth, filtering out the most severe vibrations on all sorts of rough roads, gravel tracks and cobblestones.

The second generation Domane SLR offers an improvement in ride comfort and smoothness over the previous model. Like the original Domane, this new version was developed with input from Classics specialist Fabian Cancellara. He even won the Strade Bianche during the first outing for the new bike in a professional race.

Revamped IsoSpeed

A huge amount of work has gone into the new Domane SLR. A raft of changes – a front IsoSpeed decoupler joins the new, now adjustable, rear IsoSpeed decoupler, there's a new carbon handlebar with a vibration-damping rubber insert, and lastly, space for wider 28mm tyres – combine to create a bike that is smooth and composed over any sort of rough road surface, from the poorly maintained roads of the Cotswolds to the cobbles of Belgium and France. The new Domane SLR makes a strong bid for the best endurance bike title.

The headline news with the new Domane SLR is a two-pronged approach aimed at delivering front end compliance that bettmmer matches the rear IsoSpeed decoupler, a novel development in the original bike that provides a range of comfort-boosting deflection. A common complaint with the original Domane centred around the front end feeling much stiffer than the compliant rear end. To solve this, Trek has integrated an IsoSpeed decoupler into the head tube, allowing a specially shaped carbon fibre steerer tube to bend slightly between the two headset bearings. We're only talking a very small amount of deflection, with rider weight and stem length being a factor in the bending range. Trek has also developed the new IsoCore handlebar. Within the carbon fibre layup is a layer of rubber that allows the handlebar to dissipate some of the high-frequency vibrations.

This combination works well, providing much improved – and needed – front end compliance. The bike feels much more balanced and forgiving at the front when tackling cobbles or badly surfaced roads.

The other big news is the new adjustable rear IsoSpeed decoupler, which now employs a split seat tube design, first seen on the Madone aero road bike. On the old Domane, the entire seat tube was independent of the top tube, with its movement controlled by the IsoSpeed decoupler. In the new design, the front section of the split tube is attached at the top tube like a regular seat tube, which creates a stiffer frame, with only the rear section independent. The amount of deflection is also adjustable – loosen a single bolt (which shares duty as a bottle cage bolt) and slide the dividing lever into the desired position, with the lowest setting offering a claimed 14 per cent increase in compliance over the previous Domane, while in its firmest setting it mimics the Emonda.

Ride and performance: The cobble factor

Following that launch, I was sent this Domane SLR 6, the base model in the range, equipped with Ultegra components and aluminium Bontrager wheels for review. A key difference with this bike is the H2 geometry, which basically means it has a taller head tube than the RSL bike I rode at the launch. It does make it more suitable for the vast majority of people looking to buy a Domane SLR, especially if you lack the flexibility that comes from spending 50-80 hours a week hunched over a keyboard.

Where better to test the new bike than the Paris-Roubaix Challenge? The 175km route takes in all 52 cobbled sections used by the professionals in the race the following day, and provides a tough challenge for any bike. After the first few cobbled sections had disappeared under the tyres, it was clear the work that Trek had put into this new bike had paid off; it showed a marked improvement over the previous model in terms of outright smoothness and comfort and a more rounded ride quality everywhere else.

The new Domane SLR feels stable and composed when rattling along the crown of a cobbled road, the vibrations less intrusive. The ride is just calmer. Bigger impacts, such as those on the Arenberg, can still send a jolt through the handlebar – there's a limit to how much the small range of deflection can really cope with bigger impacts – but it is on high-frequency vibrations caused by cracks in the road, ridges, depressions and smoother cobbles that the IsoSpeed decouplers, bigger tyres and carbon handlebar really make an appreciable difference and the Domane SLR excels.