Trek has launched the third iteration of its Emonda climbing bike – and now the lightweight machine adds aerodynamics to the mix. Early impressions out on the ride suggest the flagship Emonda SLR combines the flighty ride befitting of the featherweight frame, with lively but confident handling and a superb spec. Comfort could be improved with a change of tyres, however.

You can read our launch story on the new Emonda for the full tech details; here I’ll focus on the performance of Trek’s flagship machine, the Emonda SLR 9 eTap.

The Trek Emonda has always been one of the best climbing bikes out there but the new frame is designed from the ground up to be both incredibly lightweight and also more aerodynamic than previous versions of the Emonda.

That means a whole new frame shape for aerodynamics, as well as a new suite of carbon fibres and ‘secret’ processes in the manufacture of the OCLV 800-series carbon used on the SLR frame.

The 2021 Emonda is available in SLR and SL versions at launch (we've reviewed the £3,350 Emonda SL 6 with Shimano Ultegra here). The more affordable SL frame is made from OCLV 500 carbon fibre and weighs a claimed 1,142g, while the top-end frame comes in at just 698g, according to Trek. That’s for an unpainted, 56cm frame.

The fork is similarly svelte at 365g (unpainted with 220mm of steerer) and, on this SLR 9 eTap model, is combined with a SRAM Red AXS 12-speed groupset, Bontrager’s new Aeolus RSL 37 wheels (claimed weight 1,325g) and a swathe of lightweight Bontrager components. With all that kit, you’d expect a seriously lightweight bike.

That’s exactly what we’ve got here on our 58cm test bike. Finished in luxury Project One livery, our SLR 9 eTap tips the scales at an impressive 6.92kg. That’s within the weight of your sunglasses of the UCI’s 6.8kg lower limit for race bikes.

Earlier iterations of the Emonda SLR have been lighter, though. The previous generation disc frame had a stated frame weight of 665g, but that version had no such considerations towards aerodynamics, as the 2021 model does.

The Emonda SLR’s geometry is based around Trek’s H1.5 fit; an evolution of the brand’s old H1 and H2 numbers.

H1 gave you the full pro experience – a slammed and ready-to-race position – while H2 is more representative of a position the rest of us non-pros are likely to adopt.

H1.5, however, offers a great balance between race and recreation, but make no mistake this is still an aggressive machine, with a 73-degree seat angle and a steep 73.8-degree head angle.

The wheelbase is short at 992mm and the reach of 396mm isn’t overly long, however the 581mm stack is low and racy (all figures quoted are for a 58cm bike).

Compared to the other flyweight race machine launched recently, Giant’s TCR, it shares the same stack height for a comparable size and a reach just 6mm shy of the TCR’s 402mm.

On the road, the Emonda is the epitome of flighty and the sharp steering is absolutely in keeping with the bike’s all-round nimble feel, thanks to its short wheelbase and lack of mass.

As you’d expect, it’s a bike that accelerates very rapidly and covers ground with impressive ease.

Trek’s aerodynamic testing, which included research on the influence of aerodynamics when climbing, show significant gains as a result of the frame’s new profile.

That modelling showed the SLR to be 15 seconds faster up Alpe d’Huez than the previous bike (with a 70kg rider at a constant 350w).

Of course, those numbers are hard to quantify when it’s just you riding the bike. However, while the SLR won’t turn you into Alberto Contador overnight, you will feel an advantage on the ups.

Putting aside Trek’s numbers, the feeling through the pedals is a bike that’s rapid; seriously rapid.

Crucially, however, it also feels controlled. Quite often in the past I’ve been impressed by a bike’s lightweight stats and promise uphill, only to be underwhelmed by either an unforgivingly stiff chassis, or worse a bike so light that it has all of the solidity of cold noodles.

The Emonda SLR isn’t the most comfortable bike I’ve ridden in the setup tested here, for reasons I’ll come on to, but it avoids both of these pitfalls. The chassis is responsive without being overly rigid and the lightness translates into a balance between responsive handling and a confidence-inspiring ride.

SRAM’s superb Red AXS groupset does its part with quick, smooth electronic shifts across the 48/35t double chainset and 10-33t cassette.

That pairing is comparable to a more conventional 52/36t with an 11-28t cassette, though you have an extra gear to choose from at each end with SRAM’s 12-speed setup.

The SLR 9 is Trek’s absolute premium offering and the £9,700 price tag ($11,999 / €10,999) will cause a sharp intake of breath, but there are no compromises here. (You could still bulk up the price with more customisation through Project One.)

The Red AXS groupset is mated to a Red AXS Quarq D-Zero power meter chainset (with a list price of £1,070 on its own). The SLR 9 is also running Bontrager’s latest, lightest (and priciest) wheels, and the clever new RSL bar adds aero integration with proper practicality.

The cable routing runs in a channel on the underside of the bar for the aerodynamic advantages without the pain of internal routing when it comes to packing your bike for travel (not that many of us are doing much of that at the minute).

The Emonda has always been Trek’s firmest road bike in terms of comfort, compared to the luxuriant ride of the Domane, with its dual IsoSpeed decouplers, and the Madone, with the genre-blurring combination of fully-fledged aero and impressive comfort that resulted in it being crowned our Superbike of the Year for 2020.

That continues to be the case here. With no IsoSpeed in place, and Trek relying on the frame’s carbon fibre make-up to cover aerodynamics, low weight and ride quality, the Emonda certainly communicates a lot more of the road surface than its anagram-derived cousins.

In fact, compared to the previous-generation Emonda, which Trek specced with 28mm tyres on SLR models, this new one, with its cotton-rich 25mm tyres, does feel firmer.

Those 25s zip along on smooth surfaces with impressive speed but get onto anything less premium, like the chip-stone/tarmac mix common on my home roads, and the SLR can start to feel somewhat choppy and chattery.

That said, the wonderfully-ergonomic Aeolus RSL handlebar does a good job of easing high-frequency vibrations whether you’re in the drops, on the hoods or using the tactile tops. Quality Bontrager bar tape also deserves praise for keeping your hands free from numbness.

At the back of the bike, Bontrager’s take on the short-saddle design with the Aeolus Pro has also proved pleasingly comfortable for me, and is smartly padded in all the right places.

Still, even with these superb contact points in place, my first instinct would be to sacrifice a few extra grams for plenty of extra comfort by trading in the 25s for 28s, sooner rather than later.

Bontrager’s excellent R4 Classic tyres, for example, would make a perfect substitute and would only add 55g grams at each end of the SLR.

I’ve logged just over 11 hours on the SLR 9 so need a little extra time in the saddle to make a full test judgement, but first impressions are very good.

This SLR is everything a modern, fully-fledged race bike should be: stiff, responsive and extremely light, while still factoring in aerodynamics and offering confident handling. You do give up some of the comfort of the Domane and Madone in pursuit of that low weight but switching to 28mm tyres would help.

When you roll up all of the advantages of modern tech – aerodynamic performance, low weight, finely-tuned handling and the superior control afforded by disc brakes – then the future of race bikes looks very bright (and very light).