Canyon Aeroad CF SLX Disc 8.0 Di2

Canyon's Aeroad CF SLX has been one of the benchmark aero road bikes since it launched in 2014, winning rave reviews and professional races in equal measure. It's now available with disc brakes, as are all of the German company's road bikes for 2017, and the good news is that the Aeroad CF SLX Disc is every bit as good as the regular rim brake Aeroad – fast, comfortable and with predictable handling – but enhanced by the improved braking performance of the hydraulic discs. Yes, there's a weight penalty, but you'll be really hard-pressed to detect that when you're screaming along the road at full chat.

There are three models in the Aeroad CF SLX Disc range: the Shimano Ultegra-equipped 8.0 at £3,799, the Dura-Ace-equipped 9.0 at £5,199, and the £4,499 8.0 Di2 model we have on test (there's also a women's version of the 8.0 Di2 for the same price). The model we have on test has a parts list that includes Shimano Ultegra Di2 gears and hydraulic brakes, and Reynolds Strike carbon clincher wheels.

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I've reviewed several Aeroad models over the years and every time I've come away highly impressed by the performance, and a package that time and again offers good value for money compared to many other choices. Fortunately, that winning formula has not been disrupted in the adaptation to disc brakes.

The ride

Better brakes definitely let you ride faster. Rim brakes and carbon wheels might be fine in the dry, but it's a combination that massively compromises braking performance when the weather turns bad. Scary lack of retardation on steep descents in the rain is not a pleasant experience at all. That's a scenario that is completely eliminated in the Aeroad CF SLX Disc. You can enjoy the high speed it offers at all times and keep the pace up regardless of the weather and road conditions.

With its Trident 2.0 tube profiles (essentially a cut-off aerofoil, Kamm tail shape) and skinny head tube and fork blades, the Aeroad is a fast bike. It requires less effort to ride fast than regular road bikes. Even without a wind tunnel at hand, it's clear out on the road that it's an aerodynamically efficient bike. The drag is further reduced by fully internal hose and wire routing, even including around the handlebar with Canyon's own one-piece setup providing a very clean and uncluttered front-end.

As befits a race bike, the Aeroad has a slammed geometry with a 551mm stack and 397mm reach for the medium size reviewed here. The wheelbase (989mm) keeps the handling nicely balanced by providing stability at high speed and agility at lower speeds and through corners. The short 147mm head tube keeps the front end low, forcing you to adopt an aerodynamic position, the better for reducing drag. They're aggressive numbers, but if you're used to this type of position you'll be right at home. There is an element of handlebar height adjustment if you want to raise the front end height.

Perhaps one of the biggest compliments that can be paid to the Aeroad CF SLX is just how well it rides and copes with any situation. The geometry produces a bike that handles very predictably with quite a neutral manner – it's certainly an easy bike to ride despite its aggressive race credentials.

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It's well poised and balanced and you can easily exploit the frame stiffness in sprints and out-of-the-saddle climbing. Corners and descents are where aero road bikes shine, and the stiffness of the frame backed up by the thru-axles, deep-section wheels and grippy tyres provides properly quick descending potential. The hydraulic disc brakes are a revelation on demanding and challenging descents, providing a fine level of control and all the stopping power you need should a car suddenly pull out in front of you, because that's the sort of real-world hazard we non-racers have to deal with.

One of the aces up the standard Aeroad's metaphorical sleeve is the impressive comfort it offers. It's not a comfort-orientated bike but it puts some other aero road bikes to shame. Despite the slightly beefed-up frame, the new Aeroad retains that compliant feel over rougher roads, but it's possible to detect slightly more feedback through the handlebar than previously – though it is well within tolerable limits.

Watt a drag…

But don't discs cause loads of drag? Not that you'll notice in the real world. Canyon itself says the disc brakes increase drag by nearly 1 watt compared with the rim brake in its wind tunnel testing. Okay, so professional racers and armchair experts might worry about such a tiny difference, but it's impossible to notice it during general riding. The new bike still exhibits the high pace of the regular model and it's a small trade-off when you're getting the improved braking performance that this package offers for real world riding.

There's lots of debate about whether the pros should be racing disc brakes, and to be honest with you, I really couldn't care less. While a large number of cyclists might be influenced by what the pros ride, there are far more people who choose a bike that suits their riding requirements, and what I want is vastly different to what a pro needs to do their job.

That difference between us and the pros is suitably highlighted at this time of year when it's constantly raining and the roads, at least around my way, are covered in mud, leaves and other detritus that makes riding fast a sometimes tricky and potentially dangerous task. If you've ever ridden carbon clinchers in this weather you'll know that braking performance, even with the very best and most expensive carbon wheels, is seriously subpar compared with braking performance in the dry. I've had a few terrifying experiences on narrow descents with carbon rims and rim brakes over the years, I can tell you. It's enough to make you wish for better brakes.

> Everything you need to know about disc brakes

That's precisely what the Aeroad CF SLX Disc offers. You can savour all the speed, aggression, performance and handling the Aeroad offers, safe in the knowledge that your brakes are going to provide predictable performance 100 per cent of the time. On a bike built for speed, having better brakes means you can deal with situations that arise as a result of those high speeds. The difference in braking performance between the direct mount brakes on the regular rim-brake Aeroad compared to the disc version here is incomparable.

If you only every ride in perfect conditions then rim brakes are just fine, but if you want to be able to ride a race bike year-round regardless of the weather and condition of the roads, disc brakes offer a compelling advantage that's hard to ignore. The Aeroad really does let you have your cake and eat it.

The weight penalty

If there's any drawback to disc brakes it's the slight increase in weight, most of it down to the first generation Shimano equipment. Our medium test bike weighs 7.8kg, which is about 400g heavier than a similarly specced rim brake Aeroad. Some of the weight is in the frame and fork, but much of it is the callipers and discs.

The extra weight had a negligible impact on the bike's performance. It certainly didn't detract from the fun and thrills I had riding this bike. A professional rider racing over a hilly course might complain about the extra weight, but for non-racing applications – and many people will be interested in this bike simply for the speed and pace it offers for general, admittedly high performance, riding, it's of rather lower importance than other factors.

There's no doubt that aero road bikes have got lighter over the years, but if you are looking at the Aeroad CF SLX then you've already decided weight isn't the biggest priority; if you're really worried about weight you probably need to be looking at the Ultimate, Canyon's lightest road bike.

Build and equipment

As I've said, on this middle-of-the-range model you get a full Shimano Ultegra Di2 groupset with hydraulic disc brakes, with all cables and hoses neatly routed inside the frame and even inside the one-piece handlebar and stem. The Di2 junction box is neatly located in a small cavity in the bottom of the handlebar.

The semi-compact 52/36-tooth chainset in unison with an 11-28t cassette is a great setup, ideal for racing but also well suited to more leisurely riding and routes packed with hills. The RS805 flat mount disc callipers operate on 160mm rotors – Canyon is doing its own testing and finding the bigger size (Shimano recommends 140mm rotors) optimum for dealing with heat buildup.

Deep-section wheels on an aero road bike is a great look, and these new Reynolds Strike Carbon Clinchers offer high-level performance with reasonably low weight. It's a new wheelset from Reynolds and features a rim profile that is 62mm deep and 25mm wide, with no brake track and a tubeless-ready design. The new hubs are made by Industry Nine, and altogether the wheels weigh 1,710g. That's a very competitive weight for a deep-section wheelset.

They impressed, too. Without a doubt they are fast, with the aerodynamic properties of the rim shape clearly doing a great job of helping the bike to slice through the air. They're light enough to not impair climbing and are stiff enough to prevent unwanted flexing during sprints. As a light rider I'm easily buffeted around in windy weather, and on a particularly gusty ride I did experience the bike being pushed around a bit. It was controllable and not alarming, but I still had to be aware if riding in the wind.

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Canyon doesn't skimp when it comes to rubber, and most bikes across its range are equipped with high-quality tyres. This model was shod with the excellent Continental Grand Prix 4000S II tyres in a 23 front, 25mm rear width – narrower at the front for superior aerodynamics. They grip like limpets to the road surface and excel in dry and wet conditions, feeling superbly fast. They're also durable, not puncturing easily or getting cut up.

The Aerocockpit CF integrated handlebar and stem was developed specifically for the Aeroad when it first launched, and it's been a common sight throughout the range, even popping up on the Ultimate and, in a tweaked version, the comfort-focused Endurace. If there's a downside it's that you can't easily change stem length, but Canyon does size the bar width and stem length to match each frame size, and you can always specify a different one.

While I found the reach on the 100mm stem a good fit with the medium size bike, I'd opt for a 120mm if I was buying the bike. I did like the narrow 410mm width of the handlebar. Why narrow? When Canyon was developing the Aeroad and Aerocockpit together it simply found that narrow was faster. And if you're wondering where to fit your Garmin on such an oversized stem, the rubber bands will stretch or, alternatively, Canyon provides a dedicated out-front mount.

Conclusion

As I said at the start of this review, I've tested several Aeroad models over the years and been impressed every time by the performance on offer and what good value for money they are compared with many other choices.

In the Aeroad CF SLX Disc, you can enjoy the performance, handling and aero advantage of the standard design without any compromise in braking performance. The new Aeroad continues to set the benchmark for aero road bikes.

Verdict

All the speed and handling of the regular Aeroad but with superior braking