Back in 2012, the original Domane’s rear IsoSpeed was a ride-quality game changer, then along came front IsoSpeed to even up the bike’s overall ability. Now that technology has trickled down to Trek’s most affordable carbon-fibre Domane to give the SL5 the same familiar feel.
- The Trek Domane SL 5 is one of our Bike of the Year bikes for 2018. 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
To offer dual IsoSpeed at this price, of course there are some compromises, but on the face of it, they are not huge.
The frameset is constructed with less expensive 500 Series carbon fibre and the seat mast’s clever enclosing cap is alloy on this model rather than carbon. But the groupset is all 105, with direct-mount brakes, and Bontrager provides everything else from tyres to cockpit.
Unsurprisingly, every part of the SL5 is a little heavier than on more costly models, but its weight of just over 8.5kg in 56cm size is reasonable.
Direct-mount 105 brakes sort stopping Russell Burton / Immediate Media
The bike’s 175mm head tube plus 15mm tall headset top cap gave me a spacer-free, but still suitably aggressive, riding position, even though it’s Trek’s E2 relaxed front-end geometry.
Compared to some competitors, the Domane doesn’t scream endurance bike, as its shallow rims, plain profile and 25mm tyres look conventional, and that is essentially how the Domane feels. It’s a fast road bike that cunningly does its thing, allowing you to get on with doing yours.
As well as IsoSpeed, the Domane has a lengthened wheelbase and chainstays, plus a low bottom bracket for stability
Whether riding seated or standing, braking or cornering, there’s no sense of what the frameset is doing. Nothing moves discernably, but the passive IsoSpeed systems work continuously to keep vibrations and sharp bump hits from reaching you.
Both work by permitting fore/aft compliance from the carbon seat tube and the steerer tube, with fixed pivot points keeping them aligned. It’s simple and ingenious, and feels a little bit magical because it has no detrimental effect on steering or pedalling.
The first time you hit a patch of corrugated or fractured tarmac you understand what IsoSpeed does. Rather than undulations deflecting the front wheel, it absorbs and nullifies the effect of quite big hits, keeping the wheel straight and giving a smoother ride. The rear end removes jarring vibrations that can fatigue muscles faster, helping you ride for longer.
As well as IsoSpeed, the Domane has a lengthened wheelbase and chainstays, plus a low bottom bracket for stability. Its 71.9-degree head angle really helps keep the SL5 on your chosen course, but is still agile enough for reflex steering adjustments, giving it a rock solid but precise feeling.
Riding the Trek Domane SL 5 is a great experience Russell Burton / Immediate Media
It’s often said that there are great similarities between cycling and speed skating, usually in terms of the physiology required, but laying the Domane into a corner had me comparing the way it seems to bite into the road and almost slingshot out to a speed-skater’s blade carving through ice.
IsoSpeed’s bump absorption irons out small undulations to allow the 25mm tyres to grip more consistently, and even though the Bontrager rubber measures 26mm on the 28mm wide rims, if unaware, you’d think you were riding on 28mm tyres.
In fact, if the Domane can make 25mm tyres feel like 28mm, just how would 28mm rubber ride? There’s ample room to gain tyre volume thanks to the excellent direct mount brakes, but the SL5 wrings all the performance possible from these.
With such generous width, the Bontrager TLR aluminium wheelset does carry a few hundred more grams than some, but is tubeless-ready, adding versatility.
Acceleration from slow speeds is dulled a little, and powering up climbs gets tough quite quickly, but they’re fine for steady rides or training. A good set of well-matched, lighter wheels with tubeless tyres would make a big difference to the SL5, adding extra speed to its wonderful ride quality.
Bontrager’s cockpit has a vibration-reducing alloy bar, and although I couldn’t vouch for its individual performance, it’s a great shape and felt comfortable. I found the Affinity Comp saddle less comfortable than most Bontrager perches, but that’s hardly a deal breaker.
Bontrager’s cockpit has a vibration-reducing alloy bar Russell Burton / Immediate Media
Even in less expensive carbon fibre, the Domane SL5 frameset performs well, with excellent stiffness from the BB90 bottom bracket and solid front end, ensuring a lively ride that encourages you to push harder everywhere, but pays you back with reduced fatigue from constant vibrations.
The 105 compact gearing is ideal, and as a package, the SL5 is superb value for so much tech. The wheels are the most obvious future upgrade, but they’re not hard to live with really when the riding experience is this good.
Interested in what else is available at this price point? Have a look at the following list of tried, tested and reviewed bikes.