German brand goes full aero

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The Cube Litening C:68X SL is the German brand’s take on the pure aero road bike.

With a claimed drag reduction of 30 per cent versus the previous Litening C:68 SLT Disc, Cube flipped its racing bike design philosophy on its head for this latest generation of the Litening.

Moving away from a boxy, traditional design, focused on achieving the best stiffness-to-weight ratio possible, Cube went all-in on aerodynamic optimisations.

Fortunately, though, the Litening C:68X SL has retained the aigle handling of the best road bikes, but combined it with the ruthless aerodynamic efficiency of a time trial bike.

Perennial concerns about the limited adjustability of integrated cockpits aside, the Cube Litening C:68X SL is a fantastic all-round aero road bike that is great fun to ride.

Given its deep aerofoil tube shapes, narrow frontal profile and aggressively low stack, you’d be forgiven for thinking it was simply a slimmed-down version of the Cube Aerium C:68 time trial bike.

And while, like a time trial bike, the Litening C:68X SL certainly is notably fast in a straight line, it’s no slouch on technical courses with tight, twisty turns either.

At 7.54kg for my size 56cm test bike, it’s impressively lightweight too. While the overall weight isn’t the most important trait of an aero road bike, it’s also true that a bike being lighter is, all else being equal, generally a good thing.

Of course, much of that low weight can be attributed to this bike’s high-end build specification. But with a claimed frame weight of less than a kilogram, opting for one of the cheaper builds (with Shimano Ultegra R8170 Di2 or SRAM Force eTap AXS) still sees complete bike weights under 8kg, according to Cube.

Crucially, though, the Litening C:68X SL is a bike that feels fast and exciting to ride, no matter what the numbers say.

I’m also thrilled to see Cube has abandoned the drab matt-black dominated paintjobs of previous model years, in favour of brighter, more colourful options.

This model’s translucent navy (Cube calls it ‘liquidblue ‘n’ carbon’) clear coat, which allows the frameset’s carbon weave to subtly shine through, is especially eye-catching, for example.

The tan sidewall tyres and delicate colour matching on the wheels are also tasteful details that help blend everything together as a complete package.

Though the geometry figures suggest a bike that’s only slightly more aggressive than a classic road racing bike, such my Giant TCR Advanced, in practice there is a palpable difference.

Thanks to the steep 73.5-degree seat tube angle and zero-offset seatpost, for example, your saddle position on the Litening C:68X SL ends up being a touch higher and more forward over the bottom bracket.

With 389mm of reach and 563mm of stack (5mm and 1mm more than the Giant TCR), the result is a bike that practically demands you ride in an aerodynamic position.

That makes sense on a bike such as this, though, and, fortunately, it is possible to run a few of the aero-profiled spacers under and on top of the stem. This gives you the option to trial various handlebar heights before settling on a final position and cutting the steerer to length.

A seatpost with 25mm of setback is also available separately from Cube, if you prefer that.

Riding position aside, the Litening C:68X SL feels racy and sharp on the road. Like the seat tube angle, the relatively steep 73.5-degree head tube angle combined with a shortish 100mm stem offers quick handling, well suited to flicking the bike through tight corners and making split-second decisions at speed.

Standing on the pedals, whether for steep climbs or town sign sprints, also elicits a snappy response with no detectable flex or hesitation.

On exceptionally windy days, this can necessitate a need to pay greater attention, because sudden gusts that catch the front rim can occasionally translate into unwanted steering inputs.

That is possibly more a function of the specific wheelset this bike is specced with (which we’ll cover in greater detail later), but it’s also true of many fast-handling race bikes with aerodynamic wheels.

The Litening C68:X SL is also more comfortable than its stout tubeset would suggest. The decision to increase the stock tyre volume from 700 x 25c to 700 x 28c doubtless helps, and while it isn’t endurance road bike-squishy, it doesn’t batter you over broken roads either.

For the most part, the Litening C:68X SL’s finishing kit is very well thought out.

The only miss for me is the Cube Nuance SLT Road Carbon saddle, which, despite it being well made and pretty lightweight (claimed weight is 170g), I simply didn’t find as comfortable as the best bike saddles available.

That’s personal to a large extent, though, and others may find it perfectly acceptable. It’s also fairly commonplace to swap out the stock saddle on a road bike for a preferred perch anyway, so it isn’t a deal breaker.

For my testing, though, I quickly swapped it out for a Prime Primavera Shorty saddle, which has quickly established itself as a firm favourite of mine for bikes with racy riding positions.

At the front of the bike sits Cube’s own proprietary integrated cockpit, with the strikingly flattened stem and handlebar tops presenting minimal frontal area to the wind.

While stock bikes come with a predetermined stem length and handlebar width (100mm and 420mm, respectively, on my 56cm test bke), other options are available separately.

Stem lengths run from 90 to 130mm in 10mm increments, with handlebar widths of 400mm, 420mm and 440mm.

Most riders should therefore be able to find something that suits, but, as is often the case with integrated cockpits, the range doesn’t cater for those whose fit requirements or handlebar shape tastes differ from what’s on offer.

The lack of options less than 400mm wide could be a deal breaker for fans of narrow handlebars, such as myself, because the frameset is only compatible with this cockpit.

The 440mm-width option is also only available with a 110 or 120mm stem length (although I’d suggest using a 440mm-wide handlebar on a dedicated aero road bike is somewhat counter-intuitive anyway).

The Cube Litening C:68X SL is specced with a SRAM Red eTap AXS groupset.

Though its front shifting performance is bettered by Shimano’s latest Dura-Ace R9200 and Ultegra R8170 Di2 groupsets, the difference is small and SRAM’s wireless electronic groupset certainly gets the job done with minimal fuss.

Elsewhere, drivetrain performance is excellent, with quick and reliable rear shifts, and a pleasingly smooth gear progression even on the wide-ranging 10-33t cassette.

SRAM’s excellent hydraulic disc brakes also offer fantastic stopping power, especially when specced with 160mm rotors front and rear, as they are here.

Like practically all disc brake systems, the rotors absolutely howl during use in the pouring rain, but they do at least quieten down again once things dry out.

Though it means more batteries to charge, it’s hard not to appreciate the simple elegance of SRAM’s wireless system and Double-Tap shifting layout.

Red eTap AXS is also a very handsome groupset, with its mix of carbon and partly polished aluminium components helping to justify its high-end price point.

The Mavic Cosmic SLR 45 Disc wheelset is a high-quality aftermarket option from a recognisable brand. It has 45mm-deep rims front and rear, with 26mm external and 19mm internal widths.

That’s fairly conservative by recent standards, with the best road bike wheels trending towards wider internal and external rim widths, which can offer more rounded tyre shapes and improved aerodynamic performance with larger tyres.

The 19mm internal width poses no issues, but the edges of the 700 x 28c tyres do bulge beyond the width of the rims, which likely hurts aero performance slightly.

You could size down to 700 x 25c tyres to maximise aerodynamic performance, but that would come with a hit to ride comfort away from smooth roads, of course.

At a claimed 1,470g, it’s competitively light for an aero wheelset and Mavic’s Instant Drive 360 freewheel tech provides a responsive ride feel, plus the ability to swap the freehub without tools.

The undrilled rim beds are also tubeless-ready out of the box, with no rim tape required. This should make converting to a tubeless setup a little more simple, though the rims retain standard bead hooks, so you’re also free to use clincher tyres if you prefer.

As often with Mavic, the Cosmic SLR 45 Disc wheelset uses proprietary spokes and spoke nipples, meaning sourcing replacements (should you ever need to) might be a little trickier.

Mavic claims the broad, elliptical aero spokes used here are more aerodynamic than conventional bladed spokes, though, so it may be a worthwhile trade-off. The difference is as large as “5 watts”, according to Mavic, though it’s not clear how that figure was determined.

Not cutting any corners, Cube has specced Schwalbe’s excellent Pro One TLE tyres. These are amongst the best tubeless road bike tyres we’ve tested, rivalling the likes of the Continental GP5000S TR and Vittoria’s Corsa TLR G2.0 for speed, grip, comfort and puncture protection.

The biscuity-brown “transparent” side walls also complement the bike nicely, too.

Officially, tyre clearance is capped at 28mm, but in practice there’s ample room to spare even with 28c tyres fitted. This helps put it more in line with competitors such as the Cannondale SystemSix, Canyon Aeroad CFR, Merida Reacto and Specialized S-Works Tarmac SL7, all of which can accommodate tyres at least 30mm wide.

The Cube Litening C:68X SL shows the pure aero road bike can still cut it with the current generation of all-rounder race bikes.

It’s fast, relatively light, has an exciting ride quality and features an excellent build spec.

Whether or not you can match your preferred bike fit to the available sizes of the integrated cockpit is a potential (and perennial) sticking point, but otherwise there’s little to complain about.

Of course, the low weight and impressive specification doesn’t come cheap. The Cube is competitively priced compared to similarly specced competitors, though.

Whether you’ve pinned on a number or are just trying to beat your mates to the café, the breakaway is a staple of almost every race. 

To turn the odds in your favour, you need a bike to suit the task. Something aerodynamic and efficient. Nothing too heavy, so you don’t waste energy on the climbs. Comfortable enough for a long day in the saddle, but with lightning-quick reactions for searing attacks at the finish.

In this test, we pitted three leading all-rounder road bikes with an aero bent to see which provides the best mix of all-round performance when you need to turn on the taps. 

Our testing involved longer rides on the rolling terrain of the Mendips. We took in lots of climbing and descending, as well as both good and bad roads, to see where each bike excelled and where they reached their limits. 

Putting each bike through its paces back-to-back enabled us to tease out the differences in ride quality and handling, while we also considered how easy each bike is to adapt to your preferred bike fit – an important detail too often overlooked in favour of small gains in the wind tunnel.

Simon von Bromley is a senior technical writer for BikeRadar.com. Simon joined BikeRadar in 2020, but has been riding bikes all his life, and racing road and time trial bikes for over a decade. As a person of little physical talent, he has a keen interest in any tech which can help him ride faster and is obsessed with the tiniest details. Simon writes reviews and features on power meters, smart trainers, aerodynamic bikes and kit, and nerdy topics like chain lubricants, tyres and pro bike tech. Simon also makes regular appearances on the BikeRadar Podcast and BikeRadar’s YouTube channel. Before joining BikeRadar, Simon was a freelance writer and photographer, with work published on BikeRadar.com, Cyclingnews.com and in CyclingPlus magazine. You can follow Simon on Twitter or Instagram.

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