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Trek Domane 6.9 Disc review

18 Nov 2015

The Trek Domane 6.9 is one of the most versatile bikes on the planet, but is it improved by fitting discs?

Back in the 1990s Rowntree’s had a TV ad that said, ‘Bet you can’t put a Fruit Pastille in your mouth without chewing.’ A similar challenge could be laid down for the Trek Domane: ‘Bet you can’t ride a Domane without bouncing up and down on the saddle to see how much the seat tube flexes.’ It’s just something you have to do to test Trek’s claims that its bike offers unrivalled levels of vertical compliance thanks to its unique IsoSpeed decoupler. 

Trek Domane 6.9 Disc IsoSpeed decoupler

This acts like a pivot point created by a bearing hidden away at the junction between the seat tube and top tube, allowing the seat tube to flex almost independently of the rest of the bike. The idea is that on harsh terrain such as that encountered on the cobbled Classics, the Domane will offer greater comfort through absorption of bumps, while not sacrificing the high levels of lateral stiffness required to perform as a top-end race bike. And it works – it really does make a difference to the ride feel, softening blows that would otherwise be transmitted directly into your body, but with no obvious detriment to the stiffness of the lower half of the frame responsible for transmitting pedalling forces. The Domane remains sturdy where it needs to be and Trek’s BB90 bottom bracket shell feels as solid and responsive on the Domane as it does on its siblings, the Madone and Émonda. What’s more, the IsoSpeed design adds very little weight, and even in this latest disc brake guise, the complete bike (56cm, no pedals) weighs 7.3kg, so is certainly no heavyweight. 

Shock and awe

Absorbency at the front has been increased thanks to a new lay-up and profile for the fork, in conjunction with Bontrager’s ‘IsoZone’ handlebar that includes integrated high-density EVA foam. The bar is sculpted to allow the inclusion of the vibration-reducing foam pads without increasing the diameter of the bar, which works well for me, as holding on to something that feels like a pair of toilet rolls does nothing for the feeling of connection with the bike and the ground beneath. 

Trek Domane 6.9 Disc seat mast

The lasting impression of the Domane is that it offers an agreeable ride over rough surfaces while remaining spritely and capable of chasing down the odd climbing Strava KOM too. As an aside, it comes supplied with standard ‘tubed’ Bontrager R3 tyres, but the Affinity Elite wheelset is tubeless-ready so there’s the possibility to upgrade to a tubeless set-up, allowing slightly lower tyre pressures for the same rolling resistance and potentially providing a further improvement to the ride feel. 

The Domane won’t be right for everyone. Riders who prefer an aggressive set-up might find its high front end an issue, but it will suit anyone who likes to ride quickly without getting beaten up every time the road gets rough. All this, however, is old news. Three years after its launch the Domane’s credentials are well established, so the real question then is what, if anything, do the disc brakes on this latest iteration add to the equation?

Belt and braces

Trek Domane 6.9 Disc front fork

Trek has embraced thru-axle technology, front and rear, which means ditching old-style quick-releases and instead connecting the wheels via a fully encapsulated dropout together with a wider, hollow, threaded aluminum axle (15x100mm front and 12x142mm rear). The benefit should be twofold – a more accurate and secure fitment that’s also significantly stiffer – and I’m pleased to say that the Domane 6.9 Disc is the first disc braked bike I’ve ridden with zero brake rub, even when making exaggerated movements to try to induce it. On this point, the thru-axles are a significant benefit, banishing the constant ‘zinging’ of the disc rotors against the pads I’ve experienced on so many other disc bikes when sprinting or climbing hard out of the saddle. However, the trade-off comes with the aesthetics.

Disc brakes and thru-axles are technologies the road market is borrowing directly from mountain bikes. But for me, what looks acceptable on a mountain bike (which by its nature is burlier) is inappropriate on a sleek road machine. This is where the Domane 6.9 falls down. It’s a matter of opinion, but I think the dropouts and axle arrangement, especially at the front, look ugly and over-built, certainly not befitting of an otherwise stealthy carbon road bike. The rear is less jarring, hidden somewhat by the rear triangle, but is still far less visually appealing than it needs to be if this technology is to be accepted. Other brands have used thru-axles with a far less harsh visual impact, for example Storck’s Aernario Disc, which is a much cleaner looking design.

Trek Domane 6.9 Disc review

The 160mm rotor size isn’t helping either. It looks and feels like too much brake for the bike. Shimano’s R785 disc brakes are undeniably powerful, but with a sub-70kg rider the stopping force on offer here is excessive. In the wet it required an enormous amount of care not to lock a wheel. Some might say powerful, reliable brakes are a great feature for safety, but I would say you can have too much of a good thing. Dialling down the power, perhaps in this case by fitting a smaller 140mm rotor (which would also look considerably neater) would allow a greater opportunity to tap into the modulation and the ‘feel’ that hydraulic disc brakes can undoubtedly provide. With the set-up as it was on this bike I was wary of pulling on the levers hard enough to feel the modulation, for fear of locking and skidding the wheels, even in the dry. 

In terms of safety and performance, I’m generally in favour of the advent of disc brakes on road bikes, so it was a little disappointing that I found I enjoyed this disc version of the Domane less than the calliper brake alternative. I had initially expected the discs to provide even greater versatility, something the Domane already has in spades, but while the frame still impressed me, the braking if anything sapped some of my confidence to push the limits of the bike on descents and through tight turns. And as for the looks, well… that’s for you to decide.


Trek Domane 6.9 Disc
Frame Trek Domane 6.9 Disc
Groupset Shimano Dura-Ace Di2
Deviations Shimano R785 Di2 shifters and brakes
Bars Bontrager Race X Lite Isozone carbon
Stem Bontrager Raxe X Lite
Wheels Bontrager Infinity Elite TLR
Saddle Bontrager Paradigm RXL

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