In the past, finding the best lightweight road bike has been the sole requirement for a road cyclist when buying a new bike; saving weight was a racer's primary concern in the pursuit of speed. Such was the obsession that in cult book The Rider, Tim Krabbé recounts being told by another cyclist that, "Anquetil always moved his water bottle to his back pocket during climbs, so his bike would be lighter."
Conversely, the contemporary fashion for aerodynamics might, at first glance, make lightweight bikes seem like a bit of an anachronism, but there are actually still a number of sound reasons why you should consider one as your next bike.
Today, many lightweight bikes still feature prominently in our guide to the best road bikes, but with the UCI steadfast on a minimum weight limit of 6.8kg, advancements in design have looked towards improving aerodynamics and ride quality without increasing weight, to make the best lightweight bikes more enjoyable to ride, easier to own and faster over flatter terrain.
Progressive aero update to one of the most acclaimed lightweight bikes
Price: £8,999 | Weight: 7.49kg | Brake: Disc | Frame: Carbon | Sizes: XS-XXL
Women’s specific builds available
Activation fee for the integrated power meter
With its renowned blend of low weight and enormous stiffness, the Cannondale SuperSix has long been considered one of the best road bikes for climbing, but its round-tubed design was admittedly getting a little long in the tooth.
The SuperSix 2020 brings a complete design overhaul, with truncated aerofoil tubing, a sleek integrated cockpit and system designed wheels. The SuperSix maintains the glorious pedalling efficiency, low weight and razor-sharp handling, but dropped seat stays increase comfort and hydraulic disc brakes bring improved braking control and tyre clearance.
Now arguably more of an all-rounder than just a pure climbing bike, the Cannondale SuperSix does sit a few hundred grams over the UCI weight limit, but the aerodynamic gains will likely offset this on less steep climbs.
The only let-down is the activation fee for the Power2Max integrated power meter. It's brilliant that the bike comes with one of the market's best power meters already installed, but considering how much this bike costs, it's a little annoying that you have to pay an extra $490/€490 to access its full potential.
The Giant TCR Advanced SL 0 is incredibly light, stunningly stiff and it holds flatland speed well, it's an out and out super bike
Price: £9,499 | Weight: 6.96kg | Brake: Disc | Frame: Carbon | Sizes: S-XL
Weight (sub 7kg, size large)
It holds speed over flat and rolling ground well
Power transfer is similar to a dedicated aero bike
Handling confidence takes time to build
The integrated seatpost makes flying with the TCR difficult, but not impossible
No Shimano builds available at Advanced SL level
The TCR Advanced SL 0 is a world-class road race bike. All the metrics and the riding experience suggest it has managed to bring itself back in line with - if not ahead of - the competition.
With the price at £9,499 / $11,000 / AU$13,999 / €10,199, the TCR Advanced SL 0 is in the same ballpark as the S-Works Tarmac, Cannondale SuperSix EVO and the Trek Emonda.
The TCR Advanced SL 0 misses out on a perfect score due to a couple of things. The negatives of the ISP outweigh the positives and the lack of a Dura-Ace build is something that will put many riders off.
All things told, if you're forever chasing the final watt of energy, there will always be a new bike that claims to be faster, lighter, better. If you're looking for a world-class bike that brilliantly blends weight, aerodynamics and efficiency, the Giant TCR is a bike you should consider every single time.
Specialized S-Works Tarmac SL6 Disc Dura-Ace Di2
Hugely popular, WorldTour race winning lightweight bike, now more aerodynamic, more comfortable and with disc brakes
Price: £9,500 | Weight: 6.8kg | Brake: Disc | Frame: Carbon | Sizes: 44cm-61cm
Grand Tour winning pedigree
Women’s builds available
The latest version of Specialized hugely popular Tarmac retains the fantastic efficiency and handling we've come to expect, but goes and slows faster than ever before.
Time in the Specialized Win Tunnel has led to dropped seatstays and redesigned tube shapes, that Specialized claims make the new Tarmac as aerodynamic as the original Specialized Venge, even with the addition of hydraulic disc brakes.
It's pricey, but you do arguably get a lot for your money. Specialized specs its own components and wheels, but in every case these arguably rival or surpass offerings from dedicated component brands. You get a set of Specialized's S-Works Power cranks, a carbon railed S-Works Toupé saddle, carbon handlebars and the Roval CLX 50 Disc carbon wheels come tubeless ready, with CeramicSpeed bearings and Specialized Turbo Cotton tyres.
Specialized makes a big deal about the fact that each frame and fork size in the range is built with their Rider-First Engineering design, which means each size gets specific carbon layups and fork tapers, so that ride quality is maintained across the board.
Unlike some other brands, however, Specialized has decided that gender-specific geometries aren't actually necessary, and instead specs different contact point components and crank lengths on its women's specific builds. It's hard for this writer to say whether that's the right approach, but it seems to work just fine for the riders of the Boels Dolmans Cyclingteam.
Scott Addict RC Premium
So refined that Mitchelton-Scott will take to every race this season
Price: £8,999 | Weight: 7.12kg | Brake: Disc | Frame: Carbon | Sizes: 47cm-61cm
Fully integrated cockpit
Aero tube shapes
Such is the rounded performance of the latest iteration Scott's latest road bike, the entire Mitchelton-Scott team has committed to using the Addict RC Disc for its entire 2020 race calendar.
The Addict RC Premium is one step off the range-topping model in the Scott range - that accolade goes to the RC Ultimate at £10,799 - the Premium is fitted with DT Swiss wheels, a full Shimano Dura-Ace Di2 disc brake groupset, and the fully integrated cockpit that sees cables hidden from sight entirely.
Bianchi Specialissima CV Ultegra
Bianchi's range-topping lightweight frameset specced to a budget
Price: £4,800 | Weight: 7.55kg | Brake: Rim | Frame: Carbon | Sizes: 47cm-61cm
Lightweight 780g frame
Lower spec than others here
Frame has obvious aero consideration
While more premium models exist in the Bianchi range, we see this Specialissima as a great halfway step into the realms of the top-of-the-range lightweight bikes.
With the premium Specialissima frameset hitting the shelves at £3,899.99, this model completes the build with some aluminium Fulcrum wheels and a full Ultegra groupset for £900 more. At 7.55kg, it's already competitive on the scales, but if you're looking to build your way to owning the best lightweight bike, the Specialissima Ultegra could be the starting point you need.
Alternatively, if you're looking to spend big, the Dura-Ace Di2 disc version can be had with DT Swiss wheels at £10,500.
BMC Teammachine SLR01 Disc Two
Forward thinking bike design that seemed to inspire almost every other brand
Price: £9,499 | Weight: 7.14kg | Brake: Disc | Frame: Carbon | Sizes: XXS-XXL
Grand Tour winning pedigree
Dropping the seat stays for improved comfort and aerodynamics was a 2019 bike-design must-have, but the BMC commitment to progressive bicycle design is such that they debuted this feature back in 2010 on the Teammachine.
The combination of massive pedalling stiffness from the oversized down tube and bottom bracket area, combined with the comfort gained from thin, dropped seat stays, made this design a winner from the start. Cadel Evans promptly rode to victory in the Tour de France only a year later, in 2011, and it continues to be the bike of choice for most riders at Dimension Data, thanks to its blend of efficiency, comfort and perfectly balanced handling.
With the addition of hydraulic disc brakes, a semi-integrated cockpit system (that still retains adjustability for both fit and maintenance) and updated cable management, the Teammachine is more evolution than revolution, but this just shows how advanced the original design was at the time. There's little about this bike that looks out of date.
We'd perhaps like to see a nod towards more aerodynamic tube shapes on future models, but the only real downside is that you'll need deep pockets to get hold of one.
A bike that's just as quick going down hills as it is at going up them
Price: £9,700 | Weight: 6.86kg | Brake: Disc | Frame: Carbon | Sizes: 47cm-62cm
Design not as evolutionary as rivals
It should come as no surprise that Trek focused on improving the aerodynamics of the new Emonda. Trek is not alone in this with Giant, Scott, Specialized and Focus (among others) also going this route, addressing the fact that aerodynamics come into play, even when you’re not travelling 40kph on flat ground. The new frame sees truncated aerofoils on the fork legs, downtube, seat tube and seat stays which the brand says saves 183g of drag over the previous model. Interestingly the no-cut integrated seat mast is round, and so is the cap, which Trek says helps to retain compliance.
While 183g of drag is probably an abstract figure to anyone that doesn’t have an aerodynamicist within arms reach, Trek has modelled how much time a rider would save up various famous climbs around the world riding at 350-watts on the 2018 Emonda vs the 2021 Emonda. The new bike saves 15-seconds on Alpe D'Huez, 11-seconds on the Angliru, 21-seconds up the Stelvio, 80-seconds up the Taiwan KOM Challenge and 4-seconds up Willunga Hill.
For the latest edition of the Emonda, Trek as added a few new colour schemes to its Project One program ICON, KOM and Ultimate. Our test sample is the latter, which allows you full creative license over Trek’s colour palettes as well as tailoring every component. The yellow to pink fade is definitely Trek flexing its proverbial painting muscles, and the bike is anything but subtle.
An out-the-box hill climb weapon
Price: £8,999 | Weight: 6.78kg (actual) | Brake: Disc, rim | Frame: Carbon | Sizes: 46-61
Stiff and light chassis
Super-fast and reactive on the climbs
Superb value for money at this spec-level
Ride quality can be quite hard at times
The Factor O2 VAM Disc can easily hold its own against the segment's best road bikes. It's unquestionably light, superbly efficient on the flats and descends with predictability, sure-footedness and poise. Sure, there are faster bikes out there but unless you're riding at the highest level of the sport or testing it back-to-back against its rivals in a controlled environment those nuances are imperceptible to us mere mortals.
The O2 VAM doesn't profess to be a jack of all trades. It's a master of situations where the road angle tilts upwards and gravity comes into the equation. This is a place where it's at its happiest.
As far as lightweight climbing bikes go, the Factor O2 VAM represents the zenith of the genre and doesn't pretend to be anything other than what it says on the tin. If it's pliancy and outright speed you're after then you're in the wrong place - go find an aero road bike instead.
Canyon Ultimate CF SLX Disc 9.0
Great value, super-efficient lightweight bike with top-of-the-line spec
Price: £6,499 | Weight: 7.1kg | Brake: Disc | Frame: Carbon | Sizes: XXS-XXL
Wide range of sizes
Women's models available
Can only be purchased online
With Canyon's direct-to-consumer approach, it's hard to argue the value for money aspect of the German behemoth's range. While this particular model is still a considerable investment at £6,499, the 2020 Ultimate CF SLX can be had for as little as £3,899.00.
Women's versions are available, and finishing kit varies between the two genders - such as the VCLS post being included on the equivalent women's bike. Canyon claims the women's frameset is lighter and more aerodynamic than the men's version, but then it contradicts this with claimed weights of 7.07kg (women's) to 6.89kg (men's) for the ETAP disc version.
The Dura-Ace version sees an integrated cockpit, albeit with cables on show, DT Swiss ARC 1400 Dicut wheels paired with Schwalbe Pro One Evo 25mm tyres, and a Fizik Antares R3 saddle.
Cervelo R5 Red eTap AXS
A no-compromise lightweight bike that hides its performance credentials behind classic looks
Price: £8,399 | Weight: 6.9kg | Brake: Disc | Frame: Carbon | Sizes: XS-XXL
Design arguably getting dated
The bike of choice for former Giro d'Italia champion Tom Dumoulin, the Cervelo R5 is a bit of a wolf in sheep’s clothing. It would be easy to look at the traditional frame shape and assume it’s a vestige of a by-gone era (especially compared to wild aero design of the Cervelo S5 Disc), but you’d be far from the truth.
The Cervelo R5 is built from Cervelo's Squoval™ Max aerodynamic tubing, tuned to balance phenomenal levels of stiffness with low weight, whilst a stable yet racy geometry and hydraulic disc brakes offer confidence-inspiring handling. It also has clearance for 30mm tyres, so if you want more volume for grip and comfort on rough roads, this bike can handle it.
Up front, Cervelo specs its own carbon stem and handlebars. There are nods to aerodynamics here, but Cervelo hasn't yet gone down the route of full S5-style cockpit integration with the R5.
This invariably means a small aerodynamic penalty, but it does also mean you can easily change the stem length or handlebar width to suit your personal fit requirements – something that might not be possible with a fully integrated system.
Wilier Zero SLR Disc Dura-Ace Di2
Thoroughly modern lightweight bike from one of the oldest racing bike manufacturers in the world
Price: €11,100 | Weight: 6.8kg | Brake: Disc | Frame: Carbon | Sizes: XS-XXL
No women’s builds available
Despite their illustrious histories, Italian manufacturers are generally not renowned for being on the cutting edge of bicycle design. We tend to think of Italian racing bikes as beautiful, classic, perhaps even old fashioned – but the reality is that, with Wilier at least, this couldn't be further from the truth.
The Zero SLR Disc is the latest lightweight bike from Wilier. Borrowing design cues from their Cento10 Pro aero bike, it's a thoroughly modern lightweight bike. It ticks all the boxes; a super lightweight carbon frame with truncated aerofoil tube shapes, integrated handlebars with fully hidden cables, hydraulic disc brakes, carbon wheels and clearance for 28mm tyres.
Its tried and tested geometry, and stiff frame and fork mean handling is great, and its clean lines and complete cable integration make it a real looker. Wilier is kind enough to offer some very nice paint jobs as well – matte black with white detailing, matte velvet red and a glossy admiral blue. The matte black frameset is slightly lighter, but go for the red or blue for that essential touch of Italian flair.
There's no denying that this is a pretty expensive bike – Wilier retains that classic Italian bike characteristic – but you're buying into a European brand with over 100 years of experience in making bikes, and all of the racing heritage that comes with that.
As of yet, there doesn't appear to be any women's specific versions available, but, hopefully, that’s something Wilier will offer in the near future.
Best lightweight bikes explained
1. The 6.8kg UCI weight limit
With the UCI weight limit seemingly stuck at 6.8kg, 'lightweight' has been largely defined at that point, and brands have been able to focus their attention on improving other areas of the bike, instead of simply chasing grams in a race to the bottom (although, naturally, that is still a thing).
Where aero bikes often have to make compromises on things ride quality, fit and user-friendliness in pursuit of all-out speed, lightweight road bikes have tended to become the all-rounders of road cycling, with development focused more on these important, but often undervalued characteristics.
Such are the improvements in these areas that many WorldTour pros still choose to ride lightweight bikes over their sponsors' aero-bike offerings, despite the apparent penalty in aerodynamic efficiency.
2. When does a lightweight bike make the difference?
The data tells us that aerodynamic bikes are faster on flat and rolling courses, but let's be honest – the hills are still where it really counts. The important Strava segments are, generally, not boring sections of flat or rolling road, they’re hills, and, on the proper hills, lower weight still beats aerodynamics.
One relatively recent development is the appearance of disc brakes on the best lightweight bikes. Rim brakes have long been favoured because of the difference in weight, but the gap has narrowed considerably, and it's worth considering that what goes up must also come down.
You might appreciate the improved power, consistency and modulation of hydraulic disc brakes when you're coming back down that 20 per cent hill, with your heart rate pushing off the scale after a full-gas KOM attempt, and it's largely accepted that disc brakes offer better braking performance, especially when the conditions take a turn for the worse.
Perhaps more crucially, lightweight bikes still retain the power to impress your friends or family members, because weight is tangible. Show them an incredibly expensive aero bike and the first thing they'll do is pick it up and complain that, "It's quite heavy… How much did you say this cost?"
By the time you've started explaining that "over a typical 40km rolling course, performance modelling shows that this bike is 45 seconds faster at 50kph than an equivalent lightweight bike…" they'll likely have lost interest and wandered off, thinking that you got royally ripped off.
A lightweight bike provides an obvious tangible difference, and, sometimes, that provides a greater psychological benefit than the few intangible seconds offered by manufacturers.
4. Carbon copies
Unsurprisingly, carbon fibre dominates the scene for lightweight road bikes. Its unique, tunable characteristics make it the perfect material for making light and stiff bikes that excel when pointed uphill. The downside is that these lightweight frames and components tend to come at an exorbitant cost.
As the great Keith Bontrager once said: "Strong, light, cheap. Pick two." That said, If the UCI limit is what you're looking at, you don't necessarily need to buy the top-of-the-range model these days, which will often actually be lighter than the UCI's minimum weight limit. Some brands are even able to offer builds with Shimano Ultegra that can still hit the 6.8kg benchmark; just don't expect them to be particularly cheap.
Of course, bikes are readily discounted, so it's worth taking a look at our roundup of the best road bike deals to find the best bike-to-price ratio.
What do you think is the best UCI legal lightweight bike currently on the market? Are lightweight bikes even still relevant in the era of 'aero is everything'? Let us know what you think in the comments below.