Trek Domane SL Disc frameset

The Trek Domane SL is a smooth-riding road bike – even an all-road bike – courtesy of IsoSpeed tech both front and rear, which helps it damp down small vibrations and bigger hits. It's not the lightest bike out there, but if ride quality is your main concern, it's a real contender.

First of all, a quick explanation of the bike we're reviewing. The Domane SL frameset arrived at road.cc built up with the new SRAM Rival eTap AXS groupset so that we could review those components too. It's not a standard build, but we've not reviewed the Domane SL before and thought we'd take the opportunity.

> Buy now: Trek Domane SL Disc frameset from Trek for £2200.00

Our 58cm bike, complete with Zipp 303S wheels set up tubeless with WTB Exposure 700 x 30mm tyres, weighs 8.82kg (19.4lb).

Trek does offer the Domane SL 6 eTap with a SRAM Rival eTap AXS groupset for £4,200, although this model is fitted with Bontrager Paradigm Comp 25 wheels.

Okay, on with the show...

IsoSpeed is the headline news here, so let's kick off with what it actually is. You can scroll down a few paragraphs if this is old news for you.

Trek first introduced IsoSpeed in 2012, although it has evolved since then. Rear IsoSpeed came first, decoupling the top of the seat tube from the rest of the frame. The aim is to take the edge off big hits and smooth out smaller vibrations by allowing a small amount of movement at the saddle, thereby keeping you feeling fresher for longer. That's the plan.

How does it do it? Although the seat tube is fixed to the bottom bracket area in the normal way, it isn't moulded to the top tube or seatstays. Instead the tubes are joined by a pivot, allowing the seat tube to flex more than would otherwise be possible.

Front IsoSpeed is a more recent introduction, the idea being greater compliance at the handlebar. Front IsoSpeed comes in the form of a rocker cup at the top of the headset that allows the fork's carbon steerer to flex backwards/forwards, but not from side to side.

Put another way, the upper section of the headset can tilt to take advantage of the inherent flex in the steerer, meaning the stem and handlebar can move slightly in response to rough roads. See? It's simpler than it sounds.

Best of three

The Domane frameset comes in three different flavours. At the entry level there's the Domane AL, with an aluminium frame. This one doesn't feature front or rear IsoSpeed although, a little confusingly, Trek does describe the carbon fork as IsoSpeed on the basis that the legs are designed to absorb vibration. Complete bike prices start at £695, although the cheapest disc brake model is £895.

At the top of the range there's the posh Domane SLR, which comes with front and (adjustable) rear IsoSpeed. Bikes are priced from £6,600.

In the middle you get the Domane SL bikes, which are made from a lower grade of carbon than the SLRs – Trek's 500 Series OCLV, rather than lighter and stiffer 700 Series OCLV. You get both front and rear IsoSpeed, neither of which is adjustable. That means you can't alter the setup according to the terrain but, on the other hand, it's simpler.

> road.cc Frameset of the Year 2020/21

The most accessible 2022 complete SL currently available is the Domane SL 6 eTap mentioned above, although the 2021 Domane SL4, with a mostly Shimano Tiagra groupset, is £2,325.

On the road

So the big question is: how much difference does the IsoSpeed technology make? Don't think that all this tech means the Domane SL feels unlike any other road bike you've ever ridden.

First of all, if you've ridden mountain bikes with loads of travel, IsoSpeed is nothing like that. Not even on the same page. Cast all thoughts of mountain bike suspension from your mind.

When you're riding on level, well-surfaced tarmac, IsoSpeed doesn't feel unusual at all, and even over rough roads it's subtle. In some ways it feels like running wide tyres at fairly low pressures... though in other ways it doesn't feel at all like that (I'll explain in a mo).

You get just a bit of movement to insulate you from what's going on beneath your wheels, and it's more noticeable at the saddle than the handlebar. Crack into a steep-edged pothole at warp speed and you still feel it – just slightly less than you otherwise would.

The main feature, 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... you know, all those things you constantly encounter on a typical ride.

It would come in handy over cobbles too, although chances are you don't have too many of those around your way.

Again, IsoSpeed doesn't eliminate bumps and vibrations from any of this stuff, it just turns it all down a few notches. It's forgiving. The rougher the surface, the bigger the difference IsoSpeed makes. It's great on old, scuffed up tarmac and it's also pretty active on gravel roads although, naturally, the tyres make a big difference here.

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The Domane takes a maximum size of 700 x 38mm. It isn't designed as a gravel bike – and most people would prefer something a bit wider for full-on gravel – but it's brilliant for short cuts to link up two sections of tarmac, for instance, and if you fancy riding gravel on 38mm tyres, well, you can fill yer boots.

I said above that IsoSpeed can feel like you have large, low pressure tyres – but not entirely. The big difference is that a big tyre can feel squishy and mushy when you put the power down, and that can be annoying on the road.

IsoSpeed doesn't feel like that at all. There's no extra bounce when you're out of the saddle, and no additional lateral movement. The front end tracks and steers well, with no nasty surprises when you bang it hard into a fast, downhill bend.

Speaking of surprises, the frame-integrated storage compartment is a natty addition. You flick a lever on the down tube – where the bottle cage attaches – to release a plate and access the space inside.

The cover has a multi-tool slot on the back, and Trek also offers a tool roll specifically designed to fit. It takes stuff like a CO2 canister and chuck, tyre levers, a spare tube, an emergency Snickers bar... you do carry an emergency Snickers bar, don't you?

Specialized does something similar on its Diverge gravel bikes, and while packing things in these cubbyholes is a bit of an art, it's a really handy addition for emergency essentials.

Geometry

The Domane SL is relaxed by road bike standards. Trek calls it an endurance fit. I've been riding the 58cm model with a 54.8cm seat tube, a 56.7cm effective top tube, and a 19.5cm head tube. It's a tall bike with a 61.1cm stack height, while the reach is short at 38.0cm. That puts the stack/reach at 1.61 for this size.

Some people are going love how the ride position is more upright than a more speed-orientated bike's, such as Trek's Madone or Emonda, for instance, while others won't be down with it at all. It depends what you're after.

Trek says the current generation Domane is much more aero than previously – courtesy of truncated airfoil tube profiles – but there's only so far you can tweak your position, and that's always going to be more significant when it comes to drag. Personally, I can't see typical Domane SL buyers being over-concerned with aerodynamics, although I guess it all helps.

The brake hoses are exposed only between the ends of the handlebar tape and the front end of the top tube, just behind the stem, where they duck inside via a removable plate. This ensures a clean look and keeps them out of the wind.

As mentioned, the bike I've been riding has a SRAM Rival eTap AXS groupset so there are no shift cables/wires to worry about anyway, but if there were any, this is the only place you'll see those too.

Other features you need to know about include the adjustable seat mast that's particular to the Domane – held by an internal clamp accessed via a slot in the extended seatpost – and the T47 bottom bracket. Hooray for threaded BBs!

Mudguards? You can fit 'em easily enough. You get threaded holes on the fork legs (filled with itty bitty grub screws when not required) and another beneath the fork crown. You get more at the bottom of the seatstays, and fairly discreet mountings for a chainstay/mudguard bridge towards the top.

The only real downside to the Domane SL is that it's not particularly light. Trek claims a frame weight of 1,365g while, as mentioned, this complete bike came in at 8.82kg (19.4lb). Okay, the SRAM Rival eTap AXS isn't a lightweight groupset, but then a few hundred grams on the frame doesn't affect the ride as much as some people would have you believe.

The money bit

There aren't many road bikes designed to smooth the ride quite like the Domane. The most obvious rival is the Specialized Roubaix, which has Future Shock front suspension – a spring in a cartridge above the head tube that allows movement of the stem and handlebar.

The top-end Specialized S-Works Roubaix Team frameset is £3,700, but comparing prices with the second-tier Domane SL is unfair. Trek's flagship Domane SLR frameset is £3,500, so there's not a great deal in it.

Overall

The Domane SL keeps you comfortable thanks to relaxed geometry, front and rear IsoSpeed tech, and the ability to take tyres up to a whopping (by road bike standards) 38mm wide. It's as versatile as it is smooth, and if you want to mix up the surfaces you ride on while retaining plenty of speed, the Domane SL is a strong option.

Verdict

Smooth endurance bike with loads of tyre space and masses of versatility