Is this the ultimate smooth ride? Check out the Trek Domane SL 6

The Trek Domane SL is a super-popular road bike – maybe even an all-road bike when set up with the right tyres – that offers a smooth ride courtesy of IsoSpeed technology that helps to damp both small vibrations and bigger lumps and bumps. Let’s take a look at what’s going on here…

Trek introduced IsoSpeed over a decade ago – way back in 2012, if you’re taking notes –  although it has developed over the years. Rear IsoSpeed was first, decoupling the top of the seat tube from the rest of the frame. 

What does that mean? Although the seat tube is fixed to the bottom bracket area as normal, it isn’t moulded to the top tube or seatstays. Instead, the tubes are joined by a pivot, allowing more flex than would otherwise be possible. This leads to more movement at the saddle. The idea is that this takes the edge off big hits and smooths out smaller vibrations so that you feel fresher for longer.

Trek did offer a front IsoSpeed system for a while – a rocker cup at the top of the headset that allowed the fork’s carbon steerer to flex backwards/forwards – but that was ditched when the latest update was announced in September 2022.

What effect does the IsoSpeed technology have out on the road? When you’re riding on well-surfaced tarmac, IsoSpeed doesn’t feel any different from normal, and even over rough roads, it’s subtle. In some ways, it feels like running wide tyres at lower pressures than usual although, unlike big tyres, it never feels squishy when you get out of the saddle and give it the beans.

You get just a bit of movement to muffle what’s going on beneath your wheels. Hit a deep pothole at full speed and you still feel it – just slightly less than you otherwise would.

The main advantage, though, isn’t the protection from the big hits, it’s the smoothing you get from the smaller stuff: little holes, manhole covers, drains, frost damage, badly patched tarmac, kerbs on and off the cycle path… It comes in handy over cobbles too, if you have any of those around your way or fancy a trip to Northern France or Belgium.

IsoSpeed doesn't eliminate bumps and vibrations from any of this stuff, it just tones it down. The rougher the surface, the bigger the difference it makes. 

The Domane isn’t a gravel bike but it will take tyres up to a sizeable 700 x 38mm without mudguards (and 35mm tyres with mudguards) and it’s great for shortcuts to link up two sections of tarmac – towpaths, hard-packed tracks, and stuff like that.

The Domane’s geometry is more relaxed than that of something like Trek’s Madone – you get a more upright, endurance-friendly ride position here. It’s still a bike with a performance edge, though, Trek saying that it has been developed using extensive CFD (computational fluid dynamics) testing to make it more aerodynamic than the previous generation. There are no specific claims relating to aero efficiency, but the Kammtail Virtual Foil (KVF) tube shaping is reminiscent of the speed-focused Emonda and Madone frames.

With a threaded T47 bottom bracket, hidden mudguard mounts, and a storage compartment hidden inside the down tube, the Domane SL is a practical option too. There’s space in there for a BITS bag (Bontrager's internal storage solution) to store a spare tube, CO₂ inflator/cartridge, and two tyre levers with space to spare, with the bottle cage then fitting on top of this. You also get mounts on the top tube for a bento-style box or top tube bag. This is a bike that’s more than capable of hauling everything you need for single-day adventures.

The latest Domane designs are lighter than previously. Trek claims a complete bike weight of 8.9kg for the 2024 Trek Domane SL 6, built with a Shimano 105 Di2 groupset. This model is priced at £4,175. A similar bike fitted with SRAM’s Rival AXS drivetrain is £4,625. 

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www.trekbikes.com