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Trek Domane SLR – first ride review

Trek up the ante with supreme comfort on all-new Domane SLR

The Trek Domane may not have been the first endurance bike when it was launched in 2012 but it played a pivotal role in defining the genre of comfort-focused race bikes. Now Trek are back with the Domane SLR and have upped the ante once again. It’s an exceptionally comfortable machine – but one which, in its Pro Endurance geometry, retains the handling and responsiveness of a true race bike.

– Trek launch Domane SLR with front and rear IsoSpeed –

Trek launched the Domane SLR in Kortrijk, Belgium, and we were there to first hear what the Wisconsin-based firm had to say about the bike and then ride it for ourselves. If you missed our launch report from Kortrijk, you can find the full tech story behind the Domane SLR here. However, let’s quickly recap on the Domane SLR’s most important features.

Trek have revamped the IsoSpeed system to make it adjustable at the rear, while also introducing the comfort-boosting tech at the front

The Domane SLR uses a trio of technologies to improve comfort. The IsoSpeed decoupler on the original Domane used a pivot to isolate the flexing seattube from the toptube but that design has been overhauled on the SLR, which now uses two seattubes: the first extends from the seatmast and is allowed to flex independently of the second, conventional seattube, which joins the downtube and toptube as a traditional seattube would. The flexing tube is essentially a leaf spring design and is anchored to the fixed seattube by by a bolt (the lower water bottle bolt) at the bottom, and a pivot within the IsoSpeed decoupler at the top.

What’s key, however, is that the level of compliance is now adjustable. Loosen that bottle cage bolt with a 4mm Allen key, move the slider (up to increase the firmness of the rear as less of the rear seattube is allowed to flex, and down to increase compliance), and re-tighten the bolt. It’s very simple to do and takes seconds – take a look at the video below from when we changed the setting midway through our test ride.

Trek have also introduced IsoSpeed to the front, in an attempt to overcome criticism that the front of the old Domane felt comparatively harsh, compared to the plush rear. The IsoSpeed was a victim of its own success, in a sense; it was too good. On the Domane SLR, there’s a decoupler within the headtube which allows the fork steerer (which, like the previous Domane, already has an asymmetric design and reversed dropouts to help it to flex) to move fore and aft, while remaining anchored to the headtube to ensure there’s no ill-effect when it comes to handling. There’s also a new handlebar, called IsoCore, which has a layer of rubber buried within the carbon fibre lay-up to help soak up road vibrations before they reach the rider’s hands.

Other features found on the frame include hidden mudguard mounts, an integrated chain catcher, integrated DuoTrap speed/cadence sensor, direct mount brakes and a ‘Control Centre’ to house the battery for electronic drivetrains, cleverly hidden under the water bottle mounts on the downtube.

Oude Kwaremont, Paterberg, Koppenberg – and a caveat

Our 85km loop took us over three of the Tour of Flanders’ most iconic climbs: Oude Kwaremont, Paterberg and the Koppenberg, providing a relatively short but solid test of the Domane SLR’s capabilities.

It was on these roads that Fabian Cancellara rode the new Domane SLR to second at Sunday’s Tour of Flanders, while Spartacus claimed victory at Strade Bianche in March, in what was his first competitive outing on the bike, having once again played an important role in the Domane’s development.

Speaking of Cancellara, our test ride – and the initial impressions we formed as a result of it – comes with one important caveat. Trek will offer the Domane SLR in two geometries: Endurance and Pro Endurance, and we rode the latter. It’s the geometry used by Cancellara and his Trek-Segafredo team-mates, with a longer reach and shorter stack height – making for a more aggressive fit and having an impact on the bike’s handling, making it quicker and more responsive, while, on the flip side, the slacker Endurance geometry will bring more a more relaxed position and more sedate handling.

The rim brake version of the Domane SLR has room for 28mm tyres, while the disc machine has capacity for 32mm

As it stands, the Domane SLR will initially come in five builds (three with rim brakes, two with disc brakes) and all will use the standard Endurance geometry, with the Pro Endurance geometry available only if you buy the Domane SLR Race Shop Limited frameset or use Trek’s Project One custom programme.

That aside, our test bike was equipped with a Shimano Dura-Ace groupset and Bontrager’s excellent Aeolus 3 TLR tubeless-ready wheels, wrapped in 28mm Bontrager R3 tyres. Trek have significantly increased the tyre clearance on the Domane SLR. Whereas the old Domane could only take (by Trek’s recommendation) 25mm tyres, the rim brake version of the SLR comes with 28mm as standard, while disc brake models are equipped with whopping 32mm tyres. It’s a smart move, bringing (potentially) even more comfort and making best use of the bike’s versatility (there are mudguard mounts, too). Trek see the Domane SLR as a bike capable of going anywhere a gravel bike can, but with road bike handling and geometry. As an aside, if you want to go even wider, it looks like there’s room, but 28mm/32mm for rim/disc brakes is the widest Trek officially recommend.

Class-leading comfort

Based on our test ride, the (Pro Endurance) Domane SLR achieves a rare trifecta: supreme comfort, exceptional stiffness and race bike handling. The biggest compliment you can pay the Domane SLR is it offers a rare level of comfort without losing any performance edge. That, for us, is the trick with any endurance race bike; equally at home at the pinnacle of the sport in the Classics as for regular riders on the rough roads of a UK road race or sportive.

Trek say the Domane SLR’s adjustable rear IsoSpeed offers 14 per cent more comfort than the original in its lowest (most comfortable) setting, while the ride is said to be 25 per cent firmer on the highest setting. We started our first ride close to the highest setting but, even then, it was immediately evident that the Domane SLR serves up an extremely comfortable ride, particularly through the rear IsoSpeed.

The front IsoSpeed works in a similar fashion to the rear, by isolating the steerer tube from the headtube, and delivers a claimed ten per cent improvement in compliance, according to Trek

The first climb we took on was the Oude Kwaremont. It’s the longest climb in the Tour of Flanders and one of the roughest, too, with the cobbles on the bottom half in particularly poor condition. Here the challenge is picking a line to avoid your front wheel dropping into one of the huge gaps between cobbles, and staying clear of the slick mud caked across the road by vehicles clearing up after the race.

When riding on the cobbles, there’s still a discernible difference in the comfort served up by the front and rear of the bike. That will always be the case – there will always be a limit as to what can be achieved at the front on rough cobbles, without affecting the handling or resorting to a suspension system. However, the Domane SLR undoubtedly softens things up – riding on the cobbles here was a significantly less jarring experience than our previous visit – and that was nicely amplified through the rear of the bike when we dropped the IsoSpeed to its lowest setting for the Paterberg and Koppenberg. The difference isn’t night and day, like switching from a road bike to a full suss mountain bike, but it is tangible and noticeable.

Even with 28mm tyres and the rear IsoSpeed on its lowest setting, the Domane SLR feels anything but sluggish zipping along in a fast group, though we need to spend more time on the Domane SLR, on a range of rides, roads and terrain, to understand the nuances of particularly settings across the range offered, and really see what effect the rear IsoSpeed’s adjustability has on stiffness and comfort.

The cobbles of Flanders and Roubaix are at the extreme end of what a rider’s likely to see on the Domane. They will always be uncomfortable, to a degree, and with bikes like this it’s about trying to reduce that discomfort – and the Domane SLR works very hard in taking the edge off, and is impressively effective in doing so – but it’s on more ‘regular’ roads that we began to understand just how smooth the SLR is. And by ‘regular’ we mean roads which include anything from pristine asphalt, to cycle lanes, to broken tarmac with occasional potholes and cracks in the road. We’re looking forward to seeing where the Domane’s limits are, particularly with those wider tyres fitted.

It’s a little cliché to say how an endurance bike ‘floats over the road’ but that is genuinely the best way to describe the sensation of the Domane SLR. The 28mm tyres help, of course, but it is incredibly smooth through the rear IsoSpeed, and the overall ride does feel significantly more balanced than the previous Domane. Balanced doesn’t necessarily mean equal, in terms of front and rear compliance, but there isn’t an obvious sense of detachment between the two ‘halves’ of the bike.

The IsoCore handlebar buries a layer of rubber within the carbon fibre lay-up – again, to improve comfort

We still need to spend significantly more time on the Domane SLR to truly understand the benefit of the front IsoSpeed and IsoCore handlebar, and run some back-to-back testing on our local lanes, which are far from smooth. However, the times we hit cracks and bumps on the road in Flanders which would have rattled through other frames and into the rider, the SLR handled them noticeably well and stopped any jarring shocks getting through. If you want numbers then Trek say the IsoCore handlebar, which will be available as an aftermarket option from June, offers a 20 per cent improvement in compliance over a stock carbon ‘bar.

It’s also worth saying the Domane’s level of comfort may not be for everyone. The IsoSpeed technology isolates the frame from the road – it gives it that ‘floating’ feeling – but it means you don’t get much feedback from what’s going on beneath you, until things get really rough, like on cobbles. The Domane SLR goes about its business in a calm, muted manner, unlike any other bike we’ve ridden – whether that’s a good or bad thing ultimately comes down to what the rider wants from their bike.

Race bike stiffness and handling

That aside, the Domane SLR still has a genuine performance edge. Any time we were drawn into putting significant force through the pedals, whether during a short sprint or trying to bend the cranks just to keep moving on the 20 per cent gradient of the Paterberg, the frame didn’t waver, even in the ‘softest’ rear IsoSpeed setting. The Domane SLR may be built with comfort in mind, but the tube profiles, with the super-wide downtube, 90mm-wide bottom bracket shell and oversized E2 headtube, are all designed for power transfer. Cancellara didn’t seem to have any problems at Strade Bianche or the Tour of Flanders.

While the Domane SLR may be a comfort-focused machine, it’s lacking little when it comes to performance

In its Pro Endurance geometry, the Domane SLR retains the handling of a race bike, too. It’s stable over longer stretches of cobbles but remains quick and light up front. The frame feels taut and responsive to input, whether through the legs at the bottom bracket or hands on the ‘bar. Again, that’s with the Pro Endurance geometry, but when we get a Domane SLR in for a full test it will likely come with Trek’s more relaxed Endurance geometry, so we’ll see what effect that has on the stability, handling and feel of the bike. Again, whether that’s a positive or negative effect depends on the end user, but at least Trek recognise that and offer the option of both. Some will appreciate the relaxed nature of the Endurance geometry, while others will crave the aggressive of the Pro Endurance setup.

For now, signs are positive on the Domane SLR as a truly first-class endurance bike. It’s a genuinely innovative machine and, at this early stage, one which looks to set the bar in terms of comfort. We’ll deliver a full, long term review once one arrives in the RCUK office.