Trek Émonda SLR 8 road bike

Trek's new Émonda range is all about light weight and the Shimano Dura-Ace equipped SLR 8 is an incredibly lively bike that flies up the climbs, but it has many other talents too.

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Weight

Go to the Émonda page on Trek's website and you're greeted with the headline: 'The lightest production road line ever'.

"Every detail of the Émonda line, from frame design to each component choice on every model, serves the same audacious goal: to create the lightest line of production road bikes ever offered," they say.

"Émonda is the ultimate lightweight road racing machine, pushing the boundaries of what's possible for bicycle weight and ride performance."

You might be getting the slightest impression that Trek see weight as a key factor here so let's deal with that straight away.

There are three levels of Émonda frame: the S, which is the cheapest version; the SL; and the top-level SLR, which is the one we have here. The SLR is the lightest. Trek claims a frame weight of just 690g for a 56cm. That's as light as production frames come, edging out the Cannondale SuperSix Evo by a fraction to become the current Lightweight Champion of the World.

How have Trek made the frame so light? They say that they've given the Émonda the most sophisticated tube optimisation of any bike ever, with both the tube shape and the laminate designed to produce the highest stiffness-to-weight ratio possible.

Trek haven't gone after impressive aerodynamics with the Émonda – they've left that to the Madone – so most of the frame elements are round or, at least, much rounder than you'll find on an aero road bike, with thin walls. Squeeze the central section of the top tube between your finger and thumb and you can actually press the upper wall in very slightly. Don't worry, it returns to normal when you remove the pressure, but that's an illustration of how ruthless Trek have been in pursuit of lightness.

The bottom bracket is BB90 standard (90mm wide) for extra stiffness and Trek use a 1 1/2in lower headset bearing – as many other brands do on their performance bikes – for more rigidity up front. The seatstays are wide-set, attaching to the outside of the seat tube, the idea there being to provide extra stiffness without the need to use more material and increase the weight.

Trek have integrated features into the frame mould to reduce the amount of material they need to use and, therefore, keep the weight down. The carbon front mech mount, for example, is a part of the frame rather than something that has been bolted on afterwards. The same goes for the bottle cage bosses.

Rather than use a standard seatpost, Trek have gone for an extended seat tube topped with a seat mast to cut more grams, and direct mount brakes reduce the overall weight still further. The fork is superlight too: just 280g.

The Émonda SLR is available as a frameset for £3,000, or built up in six different flavours including a women's specific model. Plus, you can customise your own version through Trek's Project One program.

The super-duper top-end build is the Émonda SLR 10 which comes tricked out with a SRAM Red 22 groupset, Tune wheels and saddle, Bontrager's Speed Stop brakes and XXX integrated bar and stem (XXX is the model name, not just a space filler until I get around to looking it up). That complete build weighs in at an astonishing 4.65kg (10.25lb). It'll cost you 11 grand, mind.

Our SLR 8, priced at £5,800, gets a full Shimano Dura-Ace groupset and other components from Trek's in-house Bontrager brand, including RXL Tubeless ready wheels, an XXX OCLV carbon handlebar and Paradigm saddle.

This complete bike (without pedals) hit the road.cc Scales of Truth at 6.27kg (13.79lb) putting it among the very lightest bikes we've ever reviewed around these parts.

What's the point of such a light bike when the UCI has a 6.8kg minimum weight limit? Well, for a start, most people won't be racing in UCI-sanctioned events. Even if you do, the low weight gives you the option of running deeper section wheels, for example, without being at a weight disadvantage to other riders, or a more cushioned saddle, or some other heavy component that's important to you, like a crank power meter. Oh, and there's always the bragging rights that come with the territory, of course.

If it concerns you that all the gram shaving will result in a lack of durability, Trek offer a lifetime warranty on manufacturing defects, plus a one year warranty on the paint and finish.

Ride

About once a year a bike comes along for review at road.cc that I really don't want to send back, so I spin the test period out for as long as possible. The Émonda SLR 8 is the one for 2014. This is a bike that's astonishingly quick on the hills, flattering your climbing abilities, and it's easy to live with for long hours in the saddle.

Weighing in at about a pound below the UCI's minimum weight limit for racing, the Émonda SLR 8 takes very little coaxing up to speed. It's one of those bikes that almost makes you feel like you're cheating when accelerating out of a tight corner; I guess you would be cheating if you rode it in a UCI-sanctioned event.

The Émonda is at its best on the hills. The steeper it gets, the better the bike feels. Get out of the saddle for the severe stuff and the frame holds its shape impressively, and the same goes for the fork. When you pick up the Émonda and feel just how feathery it is, you imagine it'll bend about all over the place as soon as it comes within a yard of a flexed quad, but that's far from the case. That front end feels solid and there's barely a hint of sideways movement at the bottom bracket.

Trek say that the Émonda SLR frame is a little stiffer than that of the equivalent Madone. The figures are close but they have to compromise the Madone's stiffness slightly in order to get the extra aerodynamic efficiency. Riding the two of them, you'd be hard pressed to tell the difference, but the bottom line is that the Émonda feels like a strong, firm platform from which to launch your best high-power moves.

Like the frame, Bontrager's Race X Lite tubeless-ready alloy clinchers are lightweight and unexpectedly stiff. The rims are shallow section rather than deep and aero, and it doesn't take a genius to work out why: Trek have one eye on the scales with every component choice here.

One of the rear straight-pull spokes snapped on me while I was out on one ride, causing the wheel to go so far out of true that it wouldn't even spin between the chainstays, but that was a one off. I put a lot of miles into this bike and this was the only mechanical issue I had, so I'm inclined to put it down as 'just one of those things'. Annoying, but forgivable.

As if you needed any help getting up the climbs on a bike this light, our Émonda SLR 8 was fitted with a compact chainset with 50- and 34-tooth chainrings. It's only the H2 version (see below) that gets this, the H1 model comes with a grown-up 53/39 chainset.

I'm definitely more of a spinner than a stomper when it comes to pedalling technique, but I found this bike undergeared. The lowest combination is a 34-28. Maybe you'll like that setup but, personally, I'd have preferred a standard chainset or a 52/36 semi compact. One of those would suit the character of the bike far better, in my opinion, but you'll know what works for you.

The brakes deserve a special mention. As I said, Trek use direct mount brakes on the Émonda SLR bikes, as they do on the high-end Madones. The Shimano Dura-Ace direct mount brakes used here are fantastic. Granted, braking on an alloy rather than carbon brake track helps, but there's no doubt that these are a bit special, giving you a feeling of control even when you're slinging the bike into fast, mysterious bends. You know that there's enough power at your fingertips to save you if things get hairy. I've got nothing but good things to say about these brakes. Approved!

In terms of ride feel, I found the Émonda pretty comfortable. I had a high saddle (I always do) and that meant I got quite a bit of movement from the extended seat tube and seat mast to provide a degree of damping over the rough stuff. As ever, the saddle is going to be a matter of personal taste, but I got on well with the shape of the Bontrager Paradigm and there's a significant amount of flex in the shell.

Things are more direct at the front end with bumps, holes and gravel making their presence felt through Bontrager's XXX VR-C handlebar, but even the worst road surfaces feel relatively smooth and don't threaten to knock you off your line. I actually really like that carbon fibre bar, although some people might want a drop of more than the 124mm you get here.

If you do find yourself lacking comfort and/or not sticking to the ground over the rough stuff, wider tyres would certainly help. The Émonda SLR 8's Bontrager R4 tyres are very lightweight (I wore through the rear one quite quickly) and sticky but they're only 23mm wide. Going for 25s or even larger would considerably alter the feel of the ride – as they would on any other bike, of course.

Trek reckon that the Émonda has a 'size-specific ride-tuned performance'. In other words, they've engineered things so that each size feels and performs exactly the same. I couldn't very well jump off a 58cm model and on to a 50cm one to verify this so we'll have to take their word for it.

Weaknesses? Well, in these times when everything in the performance section of the bike world is aero-this, aero-that, Trek have produced a bike that's not designed with aerodynamics in mind at all. The Émonda is lightweight all the way.

Trek's solution is simple: if you want aerodynamics, go for the Madone. If you want comfort, go for the Domane. If you want lightweight, go for the Émonda. Okay, that's nice and simple, buuuuuut, what if you want all of that and don't have enough cash to shell out for one of each? I guess you just have to decide which aspect of the performance you value most and make your purchase accordingly.

Geometry

Our SLR 6.8 is built to Trek's H2 geometry because that's what Trek had available when we asked to borrow one, but it's also available in H1. If that makes no sense to you, H2 is a race fit, but it's not as aggressive as Trek's low and aero H1 fit.

Our 58cm model comes with a 59.6cm stack height (the vertical distance between the centre of the bottom bracket and the top of the head tube) and a 39.1cm reach (the horizontal distance between those points). The head tube is 19cm tall.

Those measurements are all very similar to – or in some cases exactly the same as – those of an equivalent Madone, although the Émonda's chainstays and wheelbase are slightly longer, the idea being to add a touch more stability.

Go for an H1 fit and you're talking about a 56.7cm stack (2.9cm lower than that of the H2 fit), a 40cm reach (0.9cm longer), and a 16cm head tube (3cm shorter). In other words, you'll be bent over and stretched further with the H1 geometry.

Geometry comes down to the individual, of course; what suits one rider won't necessarily suit another. When I first jumped on our review bike, the front end did feel too tall for me but I managed to get into a position that felt low and efficient by removing all the spacers from underneath the stem. On the whole, I'd rather have had the H1 fit but, like I say, each to his or her own. Speaking of 'her' (seamless, huh?), the Émonda SLR 9 WSD has exactly the same frame dimensions as a standard H2 Émonda.

Don't be tempted to go for the H1 geometry if you don't need it just because you think it's the more pro option. You're better off with an H2 with no headset spacers than with an H1 and a whole stack because of they extra front end stiffness you'll get as a result.

Verdict

Super light and lively road bike that flies up the climbs, with many other talents too