The products mentioned in this article are selected or reviewed independently by our journalists. When you buy through links on our site we may earn an affiliate commission, but this never influences our opinion.

2021 Trek Emonda SLR 9 eTap review

Flyweight and aero combined

GBP £9,700.00 RRP | USD $11,999.00 | EUR €10,999.00
Trek Emonda SLR 9 eTap

Our review

Everything a modern race bike should be. Rapid everywhere, confidence-inspiring handling and very, very light
Pros: Lightweight, lively handling, superbly equipped
Cons: Firm ride suffers when combined with poor road surfaces and 25mm tyres
Skip to view product specifications

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.

Advertisement MPU reviews

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.

Emonda gets an aero update

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.

Trek OCLV 800 carbon fibre
The OCLV 800 carbon fibre used to construct the frame is Trek’s latest material, and brings new materials and new construction processes to the OCLV name.
Russell Burton / Immediate Media

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.

Trek Emonda SLR
The Emonda’s sculpted top tube is shaped to optimise low weight and stiffness.
Russell Burton / Immediate Media

Trek Emonda SLR geometry

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.

Out on the road

Trek Emonda SLR 9 eTap
At 6.92kg for a large 58cm bike, the Emonda is a seriously light bike. The no-expenses-spared spec pictured here is appropriately priced, however.
Russell Burton / Immediate Media

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.

Top-end spec and a top-end price

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. 

Bontrager Aeolus RSL 37 wheelset.
The Emonda SLR 9 eTap gets Bontrager’s new Aeolus RSL 37 wheelset, which has a claimed weight of 1,325g.

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.

Bontrager Aeolus RSL VR-C integrated cockpit/bar-stem
Cable routing runs under the Bontrager Aeolus RSL VR-C integrated cockpit.
Russell Burton / Immediate Media

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).

Old-school 25s

Trek Emonda SLR 9 eTap
The Emonda SLR has impressed over 11.5 hours of testing so far, especially when it comes to climbing, but comfort could be improved by a change of tyres.
Russell Burton / Immediate Media

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.

Bontrager Aeolus RSL VR-C integrated cockpit/bar-stem
Bontrager’s new Aeolus RSL integrated cockpit has impressed us for its comfort, practicality and aero shaping.
Russell Burton / Immediate Media

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.

Trek Emonda SLR 9 eTap early verdict

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.

Advertisement MPU reviews

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).

Product Specifications


Price br_price, 5, 3, Price, EUR €10999.00GBP £9700.00USD $11999.00
Weight br_weight, 5, 6, Weight, 6.92g (58cm) – 58cm, Array, g
Year br_year, 5, 9, Year, 2021
Brand br_brand, 5, 10, Brand, Trek


Available sizes br_availableSizes, 11, 0, Available sizes, 47, 50, 52, 54, 56, 58, 60, 62cm
Brakes br_brakes, 11, 0, Brakes, SRAM Red hydraulic disc
Cassette br_cassette, 11, 0, Cassette, SRAM Red AXS 12-speed, 10-33
Chain br_chain, 11, 0, Chain, SRAM Red AXS
Cranks br_cranks, 11, 0, Cranks, SRAM Red AXS
Frame br_frame, 11, 0, Frame, Trek Emonda SLR, OCLV 800 carbon fibre, Project One paint
Front derailleur br_frontDerailleur, 11, 0, Front derailleur, SRAM Red eTap AXS
Handlebar br_handlebar, 11, 0, Handlebar, Bontrager Aeolus RSL integrated bar/stem
Rear derailleur br_rearDerailleur, 11, 0, Rear derailleur, SRAM Red eTap AXS
Saddle br_saddle, 11, 0, Saddle, Bontrager Aeolus Pro, carbon rails
Seatpost br_seatpost, 11, 0, Seatpost, Bontrager carbon seat mast cap
Shifter br_shifter, 11, 0, Shifter, SRAM Red eTap AXS
Stem br_stem, 11, 0, Stem, Bontrager Aeolus RSL integrated bar/stem
Tyres br_tyres, 11, 0, Tyres, Bontrager R4 320 clincher tyres, 25mm
Wheels br_wheels, 11, 0, Wheels, Bontrager Aeolus RSL 37, OCLV carbon fibre, tubeless-ready