Canyon Ultimate CF SLX Disc 8.0 Di2 review

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Canyon has updated its road catalogue by adding a disc brake version for every carbon road bike in its collection. This includes the company’s long-running flagship, the Ultimate CF SLX, and in this review, Australian tech editor Matt Wikstrom takes a look at what the update has to offer.

It has been about five years since disc brakes first started appearing on road bikes and we’ve finally arrived at the point where every major manufacturer has embraced the braking system. Where once any given brand’s road catalogue might have contained a single disc-equipped model, now there can be several. And more often than not, disc brakes have been trickling up from lower priced endurance-oriented bikes to high-end race bikes.

In some instances, manufacturers have chosen to replace their rim brake-equipped bikes with disc brake versions, but many have opted to support both braking systems, at least for some models. Shimano’s recent overhaul of its Dura-Ace groupset caters for both brake systems, so there is no danger that rim brakes are about to be abandoned by the industry.

Of course, opinion on disc brakes for road bikes remains divided, with the UCI and the professional peloton the most obvious holdouts. The advantages and disadvantages have been discussed ad infinitum, however it is the threat of the rotors that most concerns the peloton. As a result, it seems likely that disc brakes will need to evolve a little further before they become race legal.

Canyon is no stranger to road disc bikes, having created its first road disc bike in 2006. Built around the company’s F10 frameset (the forerunner to the Ultimate CF SLX), it was one of several novel project bikes created by Hans-Christian Smolik. Having created a 3.7kg bike in 2005, Smolik turned his attention to disc brakes. In the end, a variety of one-off parts were needed to complete the bike including brake/shifter levers, 120mm rotors, and a unique front hub and fork that could accommodate dual rotors and callipers, one on each side of the bike.

Clearly, the bike was well ahead of its time and perhaps the experience tempered Canyon’s enthusiasm for disc brakes when they start to re-emerge around 2011. At the very least, the company probably understood the need for proven hardware, so the first generation of road disc brakes and bikes passed before Canyon unveiled its prototypes at Eurobike in 2015.

The Endurace CF SLX was the first of Canyon’s road disc bikes to hit the market, however it was only a matter of months before the company announced disc brake versions for the rest of its carbon road bike collection for 2017. As a result, buyers now have a choice of disc or rim brakes for Canyon’s Aeroad CF SLX, Ultimate CF SLX, Ultimate CF SL, and Endurace AL. Canyon’s highest- priced road bike, the Ultimate CF EVO, remains rim brake only, as does the Ultimate AL SLX, while the Endurace CF SLX and lower-priced Endurace CF SL are only available with disc brakes.

For this review, I spent a few weeks riding an Ultimate CF SLX Disc 8.0 Di2 supplied by Canyon Bicycles Australia. This model was equipped with Shimano’s Ultegra Di2 groupset and Mavic’s Cosmic Pro wheelset and sells for AUD$6,999/£4,399/€4,899.

Before the Ride

The Ultimate CF SLX has been a mainstay in Canyon’s road catalogue since 2005. In that time, the frameset has undergone a few revisions to yield the current fourth-generation design. After a decade of refining strength and weight, Canyon’s engineers concentrated on improving aerodynamics and comfort for the latest iteration. While the former provides a marginal gain in performance, it was the latter that I found most noticeable when riding the bike for the first time.

All of the features introduced to the fourth-generation Ultimate CF SLX have been preserved for the new disc brake version of the bike. In broad terms, the fork and stays had to be re-designed to withstand the change in braking forces while extra clearance was added for wider tyres. Unsurprisingly, the Ultimate CF SLX Disc frameset adopts the same standards as the Endurace CF SLX, namely 12mm thru-axles, front and rear, flat-mount disc callipers, and 160mm rotors for all but the smallest frame size (which gets 140mm rotors instead).

According to Canyon, the introduction of disc brakes adds ~70g extra weight to the frameset with a 3.3W penalty (at 45km/h) when compared to the rim brake version of the Ultimate CF SLX. Interestingly, the results from Canyon’s wind tunnel testing indicated that most of that aerodynamic penalty was attributable to the disc brake-specific wheelset that requires extra spokes, crossed lacing patterns, and larger hub bodies.

The rest of the specifications for the Ultimate CF SLX Disc remain unchanged: oversized head tube with a 1.25inch fork steerer, BB86 bottom bracket, internal cable routing for the brakes and derailleurs, integrated seatpost clamp, 27.2mm seatpost, and electronic- and mechanical-specific framesets.

The geometry of the Ultimate CF SLX Disc is essentially identical to the rim brake version, however the new bike has longer chainstays (415mm vs 410mm) and a slightly longer wheelbase. There are still seven frame sizes to choose from, as shown in the table below:

The Ultimate CF SLX Disc has reasonably aggressive frame geometry though Canyon specifies relatively short stem lengths for each frame size. The bike continues to use the same seat tube angle (73.5°), fork rake (41.5mm) and chainstay length (415mm) for all frame sizes. It’s important to note that each bike is delivered with 27.5mm of spacers for stem height adjustment.

At this stage, there are five builds available for the Ultimate CF SLX Disc utilising Shimano or SRAM groupsets and hydraulic disc brakes: Ultegra mechanical (8.0), Ultegra Di2 (8.0 Di2), Dura-Ace mechanical (9.0), eTap with Mavic Cosmic wheels (9.0SL), and eTap with Zipp 404s (9.0 Aero). In contrast, buyers looking at the rim brake version of the Ultimate CF SLX get a choice of eight or more builds (depending on the country the buyer is in).

That isn’t the full extent of options for a disc brake-equipped Ultimate though, since there are another five builds for the lower-priced Ultimate CF SL Disc. At face value, the SL Disc frameset is identical, however it doesn’t use the same level of construction materials as the SLX Disc, so the bikes are cheaper.

In every instance, each bike has the same clean lines and Canyon’s simple matte finishes. Those models featuring Canyon’s Aerocockpit (integrated bar and stem) look a little sleeker, and according to wind tunnel testing, also save a few watts.

The Ultimate CF SLX 8.0 Di2 sent for review featured the following parts: Shimano 11-speed Ultegra Di2 groupset (52/36T semi-compact cranks and 11-28T cassette) with R785 hydraulic levers, flat-mount RS805 disc callipers, and RT99 Ice Tech rotors; Canyon carbon H36 Aerocockpit and S13 seatpost; Mavic Cosmic Pro Carbon Disc with 25c Yksion Pro tyres; Fizik Antares R5 saddle. Total weight for the size medium was 7.89kg with two bidon cages but no pedals.

As mentioned above, the Ultimate CF SLX 8.0 Di2 sells for AUD$6,999/£4,399/€4,899 with a choice of two colours (stealth/asphalt grey or gran tourismo blue). It’s a pretty good price given the choice of components however buyers looking for a bargain should consider the Ultimate CF SL Disc 9.0 Di2 or the Ultimate CF SL Disc 9.0 Aero, both of which sell for AUD$5,199/£3,249/€3,599.

Canyon sells all of its bikes via its webstore that is open to many parts of the world (there are some notable exceptions, such as North America, but that is slowly changing as the business expands into new markets, with the USA set to be the next). Each bike is shipped from the company’s headquarters and assembly plant in Koblenz, Germany, requiring only minor assembly upon delivery (see my review of the Aeroad for a look at this).

There is no way to test ride a Canyon without travelling to Koblenz, however buyers are free to return the bike within 30 days of delivery for a full refund if they aren’t satisfied with it. The company will also work with the customer during this period to address any issues related to the fit of the bike.

Every Ultimate CF SLX Disc is supplied with a six-year warranty for the frame and forks along with any necessary accessories (e.g. Di2 charger) and tools for assembly. For more information, visit Canyon Bicycles.

After the Ride

The Ultimate CF SLX is a bike I know well. The third generation Ultimate provided a near perfect blend of traits when I reviewed it in 2014, yet Canyon found a way to improve upon the mix with the fourth-generation chassis barely one year later. As I took to the Ultimate CF SLX Disc, I had a good idea of what to expect, so the only thing I was curious about was what kind of impact disc brakes would have on the performance of the bike.

In some ways, I had my answer within moments of lifting the Ultimate CF SLX Disc 8.0 Di2 out of its box. At 7.89kg, the bike was ~1kg heavier than a similarly equipped Ultimate with rim brakes. Thus, while Canyon’s engineers may have worked hard to keep the weight of the Ultimate CF SLX Disc frameset as close as possible to the rim brake version, they were powerless to offset the extra weight associated with disc brakes.

This is not something unique to Canyon. I had already noticed it for a few of the road disc bikes that I’ve reviewed recently, such as Giant’s TCR Advanced and Cannondale’s SuperSix EVO. Both of these are bikes are typically sub-7kg with rim brakes but they end up close to 8kg with disc brakes.

While the extra weight is equivalent to little more than an extra water bottle on the bike, it can blunt the performance of the bike. This was especially obvious for the Ultimate, because the rim brake version was so impressive for its responsiveness and agility. The Ultimate CF SLX Disc 8.0 Di2 simply lacked the same kick or spark as the rim brake version when it came to tackling a climb or punching over a short, sharp pinch in the road.

The Mavic Cosmic Pro Carbon Disc wheelset (that has an alloy rim bed) supplied with the bike weighed in at 1,780g. Swapping to a lower-profile and lighter wheelset had an immediate effect on the bike, restoring much of the Ultimate’s original zippiness. In absolute terms, the difference was largely a matter of nuance, but once the lighter wheels were fitted, I felt like I was starting to get the best out of the bike.

This difference in performance was really only felt in the hills. On flat or mildly undulating terrain, there was much less to criticise; indeed, I found myself preferring the Cosmics for the aggressive rumbling noise that they added to the bike. I’m also inclined to trust my impression that the bike was a little faster, since there’s plenty of wind tunnel data demonstrating that 45mm wheels are faster than 30mm wheels (though I can’t prove it).

The responsiveness of the Ultimate was the only thing affected by disc brakes. All of the bike’s other traits were exactly as I described for the fourth generation Ultimate CF SLX with rim brakes.

Thus, the integrated seat clamp that was designed to add extra compliance had me thinking that that my saddle was suddenly plusher, and on a few occasions, that the rear tyre needed more air. It was a subtle effect compared to extra bounce of Canyon’s VCLS 2.0 seatpost, and one that I much prefer.

The amount of compliance through the front end of the Ultimate CF SLX Disc was a pleasing match for the saddle. While the bars never felt as plush as the saddle, my hands didn’t suffer from any undue shock or vibration, and it made for a great sense of balance. Overall, the Ultimate CF SLX is a remarkably comfortable bike, with or without disc brakes.

The steering and handling of the Ultimate CF SLX Disc was superb, upholding the high standard that was set by the third-generation chassis. At the time, I described it as “precise” and “confidence-inspiring”. A year later, it was still a standout feature for the fourth-generation Ultimate, and the addition of disc brakes have done nothing to alter that.

That’s because the Ultimate CF SLX Disc offers as much high-speed stability as the rim brake version, and it’s just as easy to turn. On steep descents, I found that there was no need to grip the handlebars to keep the bike steady; a light hold was all that was needed. I could sit back and take it easy or move forward and lower my centre of gravity to attack the corners.

I normally opted for the latter, and had a lot of fun in doing so, because the bike was always so willing to go where it was pointed. There was no need to set up for the corners or concentrate on the exit. As such, I’m almost tempted to describe the behaviour of the bike as intuitive since there was always time for last-second corrections.

I’ve spent a lot of time riding road disc brakes and I’ve reached the point where I’ve started to take them for granted. On a day-to-day basis, they don’t do anything to elevate the performance of a bike until it starts raining hard, and then the rider can enjoy little or no change in the quality of braking (though there’s likely to be some squealing from the brakes).

With that said, disc brakes are bringing new freedom to road bikes because they can accommodate much wider tyres, which is something that Canyon have capitalised upon for the Ultimate CF SLX Disc. As a result, tyres up to 33mm be can be fitted to the Ultimate, which brings it close to a cyclocross bike.

Indeed, the 25c tyres fitted to the Ultimate CF SLX Disc 8.0 Di2 were dwarfed by the amount of clearance at the fork crown and stays. Having explored the influence of tyre width on the performance of the Endurace CF SLX late last year, I can tell you that large tyres (e.g. 30c) will improve the grip and comfort of the bike for unpaved roads, while smaller tyres (e.g. 25c) will maximise the agility of the bike for on-road racing.

Does a race-oriented road bike like the Ultimate really need the capacity for wider tyres? Maybe not, but it appears that favour for wider tyres is on a definite upswing, so it can only increase the versatility and appeal of the bike. With that said, wider tyres won’t necessarily transform the bike into a gifted gravel grinder. Gnarly terrain littered with rocks, ruts or potholes really demands 40-50c tyres, so there will be a limit to the kind of terrain that can be conquered with the Ultimate CF SLX Disc 8.0 Di2.

Final Thoughts and Summary

The Ultimate CF SLX Disc 8.0 Di2 is a great bike that has a lot to offer including superb handling and lots of comfort along with extra braking confidence and the scope to use larger tyres. However, it doesn’t make the most of Canyon’s exquisitely engineered chassis. The rim brake version of the Ultimate CF SLX is simply a better race bike because it is lighter, more agile, and as it turns out, much cheaper to buy.

Consider the rim brake-equipped Ultimate CF SLX 8.0 Di2: this bike is equipped with an Ultegra Di2 groupset and Mavic Ksyrium wheels, weighs 6.7kg, and sells for AUD$5,799/£3,599/€3,999. As long as the buyer isn’t hoping for all-weather braking and/or doesn’t need 30c tyres, this bike will be more exciting to ride than the heavier and more expensive bike reviewed here (plus, it will be race-legal).

Of course, such arguments won’t be relevant to all shoppers. The Ultimate CF SLX Disc is not a dedicated race bike, so my criticisms about the extra weight will only go so far. Importantly, the difference between the rim and disc brake versions of the Ultimate CF SLX is no more than an edge in performance, and in either guise, I still count it as one of the best carbon road bikes on the market.


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