In for review: Scott Addict RC Ultimate hits the scales at 5.9 kg

The Addict has been a staple of Scott’s road lineup since 2007 when its original lightweight form emerged as a climber’s ally and one of the favourites on the WeightWeenies forum. This new Addict – the fifth generation of the platform – is certainly a bike that will pique the interest of weight-obsessed cyclists. 

The headline pushed by Scott at the bike’s press launch in Girona was that the Addict RC Ultimate is the lightest production road bike on the market. The top-spec Ultimate model tips the scales at a remarkably feathery 5.9 kg for a size medium. This weight is even more impressive when you find that it is fitted with 28 mm tyres, deep-section wheels, and a nod to aerodynamic design. As is increasingly common with even ultralight bikes, the Addict isn’t purely one-note, as Scott claims it’s as slippery in the wind as the previous-generation Foil aero road bike. 

I’ve managed just a couple of rides on the new Addict RC and have only just received a bike for further testing on familiar roads. A full review will come in future, but for now, here’s what to know about this new flyweight machine along with some early impressions. 

The long road back to sub-6 kg

The 5.9-kilo benchmark that Scott was looking to achieve was also a considered number that harks back to the original Addict RC, which also tipped the scales under 6 kg. Of course, back then road bikes were a very different affair. Integration was an alien word to bike designers, disc brakes were the reserve of mountain bikes, anything aerodynamic was in its own class of bike, and battery-powered derailleurs were still two years away. For a time it was easy to hit the UCI’s 6.8 kg minimum weight limit, but even with the integration progression, the adoption of hydraulic disc brakes and a focus on aerodynamics meant fewer bikes approached that threshold. The Addict re-breaks the barrier in a big way.

The new Addict RC is claimed to have taken four years to come together. Max Koenen, engineering project lead on the Addict RC project, said, “By modern standards, a race bike has some requirements which add weight to a full bike, which we needed to save on the frameset. Some examples are hydraulic disc brakes, electronic group sets, wide tyres with proper grip and big cassettes. All these things are adding weight to the complete bike.

“We were asking ourselves, ‘Can we do that again? Can we build a bike at the same weight limit or at the same weight as the 2008 model?’ And we were pretty convinced about that because, within these 15 years, things have changed – not only the requirements but also the development processes and also the technologies.” 

The core design goals the team at Scott settled on for the Addict RC were to create a sub-600 gram frame, be the new benchmark in integration, improve both aerodynamics and comfort whilst preserving stiffness, and do all that whilst increasing tyre clearance to 34 mm. According to the company, every component of the Addict RC has been analysed to systematically remove weight where possible. 

At a glance, the silhouette of the new Addict RC is reminiscent of the previous model, albeit with a few tweaks. Through their own testing, Scott found that the Addict RC was 12 watts faster than the outgoing model and 9 watts slower than the latest Foil RC at 45 km/h. The aero improvements, especially around the head tube of the bike, mean that the Addict RC is said to be as aerodynamic as the previous-generation Foil. 

Adapted geometry for wider tyres 

One of the key trends the design team observed during the design process was the increasing use of wider tyres in professional racing. Riders were notably moving towards 28-30 mm tyres for most races, with even larger sizes being desired for specific events like Paris-Roubaix and Strade Bianche. To anticipate the progression of this trend, the team set the target of 34 mm tyre clearance for the new Addict RC. According to the brand, the bike can accept even wider tyres than this when built with a SRAM groupset, as the limiting factor on Shimano builds is the clearance between the tyre and the front derailleur. 

But simply increasing tyre clearance without adjusting the geometry negatively impacted the bike’s handling and performance. To address this issue, Scott implemented several key geometry changes in order to retain the Addict RC’s race focus with 30 mm tyres fitted.

Firstly, fitting wider tyres lifts the bike higher off the ground, shifting the centre of gravity upward. So the bottom bracket has been dropped to compensate, retaining the bottom bracket position relative to the ground compared to the previous model Addict RC. 

At the front of the bike, the fork’s geometry has been overhauled with a longer fork rake. With higher-volume tyres fitted, the trail of the fork naturally increases, slowing down the responsiveness of any input. The longer-rake fork allows the trail to be reduced to keep the bike’s agile feeling and responsive handling, particularly on descents. A fortunate knock-on effect is that the longer rake positions the front wheel farther away from the rider’s toes, preventing toe overlap – something that smaller riders will be particularly pleased to hear. 

To counteract the increased wheelbase of the longer fork rake, the team shortened the chainstays to 410 mm, the minimum length permitted for compatibility with Shimano rear derailleurs. To improve the tyre clearance, the team shifted the seat tube forward by 5 mm and then equipped a 5 mm offset seat post to maintain the original saddle position relative to the bottom bracket.

HMX and HMX-SL Frames 

There are five models in the Addict RC range. Four of the models (RC30, RC20, RC10 and RC Pro) all use the same HMX carbon fibre chassis with the frame weighing a claimed 650 grams for a medium frame size and 295 grams for the fork. This is a 172- and 49-gram saving, respectively, over the previous-generation Addict RC. This brings the HMX frame 35 grams under the claimed weight of Specialized’s S-Works Tarmac SL8. However, this quoted frame weight from Scott was for an unpainted frame with the finished frame with paint around 40-50 grams heavier than this for the Ultimate and around 70 grams for the colourways on the Pro and below models. 

The RC Ultimate steps things up using the brand’s higher-modulus HMX-SL carbon fibre layup. The Ultimate framesets are also manufactured in a separate facility that uses a new construction process that helps facilitate the further reduction in chassis weight. Part of this new process allows for the membrane used in the fork’s construction to now be removed. Until now the tight and intricate internal profile of the fork meant that the membrane was left in situ. This process saves just a handful of grams, but on a bike like this every gram that can be saved is a move closer to the 5.9 kg target.

 The Ultimate frame comes in at 599 grams with a fork weighing 270 grams. This is a 161- and 54-gram saving over the outgoing RC Ultimate. For reference, Specialized claims that the S-Works Aethos frame comes in 14 grams lighter at 585 grams. 

The diet hasn’t been restricted to just the frame and fork. with a further 253 grams shaved off the 2022 model through the accompanying (proprietary) components. The result is a total saving compared to the prior versions of 474 grams for the HMX build and 468 grams for the premium HMX-SL. The previous Addict RC was hardly a heavyweight, so the saving of nearly half a kilogram (a full pound) is an impressive feat.  

Part of the frame’s crash diet was achieved through extensive FEA (Finite Element Analysis). Through this method, Scott learned that the seat tube could be redesigned to save weight. On the previous generation Addict RC, the seat tube was a uniform thickness all the way through. On the new Addict RC, the seat tube is thickest around the clamping area before it reduces in thickness farther down. 

As one of the first brands to move to press-fit bottom brackets, Scott is sticking with the technology, in this case, a PF86. Scott believes that mechanically this is the best (and lightest) solution for mounting bearings in this area so long as the manufacturing tolerances are controlled. 

One bolt to rule them all

Earlier in the year the new Canyon Aeroad introduced a single bolt size across the bike. With the Addict, Scott has followed suit, adopting a one-tool-to-adjust-everything strategy. The bolt it settled on is a T25 Torx due to its ability to withstand high torque input whilst being compact enough to still work across all the areas of the bike. 

By contrast, Scott claims that to achieve the same strength properties using a hex head bolt the default size would need to be 6 mm, a size deemed impractical and a little ugly for purpose. The only area where a T25 was not used is the axles which sport a typical 6 mm hex head. 

This one-size bolt strategy allows for a very simple tool to be used to adjust any of the bike’s fasteners. With the exception of the Ultimate HMX-SL build, all Addict RC models include a small bar end-mounted multi-tool that provides the required T25 Torx and 6 mm hex tools. 

Goodbye, Contessa 

The release of the Addict RC signifies the end of the road for Scott’s women’s-specific range. Contessa was the name given to the brand’s women-specific models; however, the brand feels that heading to a completely unisex range going forward is the best option for giving all riders the choice of spec and colour they want. It’s a decision that seemingly follows the likes of Specialized and Trek, which also discontinued their women’s-specific ranges and instead broadened the general range.  

Charlotte Pythoud, graphic designer for the Addict RC programme, was part of the Contessa programme in the past, but more recently was a voice saying it should stop. When asked why, she explained, “For me, the trend is not saying this is a woman’s product and this is a man’s one. I think it’s more what’s trending, what’s in fashion. We try to still have that feminine touch but that feminine touch is not always for women and you see the same with jersey colours when it changed like 10 years ago.”

Pythoudi also explained that many men at Scott had been choosing to ride Contessa bikes simply because of the preferred aesthetic. For employees of the brand, this move is easily justifiable but to the consumer market, convincing men that they could buy a ‘women’s specific’ model if they preferred the colourways on offer would be a far harder task. Instead bringing everything under one range gives everyone the freedom to choose exactly what they want. 

The Contessa range historically used the same chassis as its corresponding Scott counterpart – albeit with a different build kit, price point, and colourway. Pythoudi explained that this can feel limiting for female cyclists who don’t feel they could get a top-of-the-range bike as the Contessa range topped out with mid-tier builds. 

The brand believes that moving to a unisex product range opens up all designs to all customers and creates a more open and accessible range for any rider. Speaking about the broader cycling market, Pythoudi explained, “As a woman, I’m always pissed because the women’s thing is made in pink or blue and it’s also cheap because [the assumption is] women want to buy cheaper products. We don’t need it in bikes because it’s the same product at the end, you can buy whatever you want and this way you can try to match as many customers as you want.

“Of course, dealers have to order accordingly if you think about sizes because if they think this is a product that’s going to be sold more to women, then you also have to order more extra small and double extra small bikes. We try to offer as broad [a range] as possible to really match as many people as possible for both women and men. Honestly letting Contessa go let us have more of this kind of fashionable colourways that are not only for women but also at a higher level,” Pythoudi added. 

A comfortable bike is a fast bike

The Scott design team repeated the message that nothing on the new Addict RC was unintentional. An area where this intent was particularly noteworthy was around the junction between the seat stays and seat post. As the seat stays travel away from the dropout they gently roll inwards. This is aesthetically very pleasing and creates a smooth transition into the seat post, however, the reason behind this runs far deeper than looks. 

Through Scott’s internal testing when analysing frame compliance, they found that the flex of the seat stays doesn’t actuate in the vertical axis. Instead, the flex occurs laterally with the chainstays bowing outwards under impact and vibrational loads. That understanding allowed the engineers to maximise compliance whilst retaining the stiffness expected of a premium race bike. 

Scott has equipped the bikes with a Syncros Comfort seat post for all models aside from the Ultimate and Pro. A cutout towards the top of the post can fit a magnetic rear light or just have a fairing placed over it. It is very similar to the post found on the current generation Foil, albeit a little shallower. It’s a small-seeming thing, but this cutout design is claimed to increase compliance at the saddle by 36%. 

New Schwalbe rubber breaks cover

There was little that would be disclosed about the tyres found on the Ultimate. From afar they look just like any other Schwalbe One Pro tyre we have grown accustomed to. Upon closer inspection, the tyres are marked up as ‘Aerothan,’ sharing its name with the brand’s Aerothan TPU inner tube. The Addict marks the tyre’s first appearance.

Exactly what Schwalbe has developed with this new tyre will be revealed at a later date by the brand themselves. What I can tell you is that the Aerothan tyre is not tubeless-ready, which means that it must be run with an inner tube. Naturally, Schwalbe recommends the Aerothan tube and says that this setup offers minimal rolling resistance and is the lightest setup. 

This may be the case but having a tubed tyre on a hookless rim seems like it is asking for trouble. It is already a minefield when it comes to understanding the ETRTO maximum pressure limits and adding an inner tube into the mix certainly won’t do anything to ease this. Regardless of tubeless or inner tube setups, the ETRTO max pressure of 5 bar (72.5psi) on a hookless rim must be abided by. 

More will be revealed in good time when Schwalbe shares further details on the Aerothan tyre but my short-term initial impression is the tyre is confidence-inspiring on descents and even with the tubed setup no one on the 20-strong press trip got a puncture so there is something to be said for that. 

Build kits and pricing

The Addict RC Ultimate that I spent the most time on is the brand’s flagship model with a build kit and price worthy of flagship status. Finishing off the HMX-SL frameset is a mix of Syncros components (including a new one-piece cockpit), Syncros Capitol SL wheelset, and  SRAM’s Red AXS groupset with Quarq power meter. 

Joining the Ultimate are four other builds that all use the HMX frame and Shimano groupsets. The RC 20 and 30 also use a two-piece bar and stem rather than the fully integrated IC-R100-SL cockpit found on the pricier models. 

The Addict RC Pro is built to come in ready to race at the UCI’s 6.8 kg minimum weight limit once pedals and cages are fitted. Shimano’s Dura-Ace Di2 takes care of shifting whilst the Syncros wheelset takes a step down to the Capital 1.0S 40 mm wheels. These are more traditional in their spoke and rim design than the single-piece construction of the SL’s. Something that the Ultimate omits in the search for absolute weight weenie status that is present on all other models is a small Torx/Hex tool enclosed in the bar end.

The Schwalbe Aerothan tyres are only found on the Ultimate build with Schwalbe’s Pro One and One tyres coming fitted to the rest of the range. The Ultimate is also the only model to come with 28c tyres with the rest of the range opting for 30c tyres to increase comfort. 

First ride impressions 

I only rode the Addict RC a few times during a press launch in Girona, so I have yet to fully acquaint myself with the bike. For that, a full-length review is in the works for the coming months.

My experience with such light bikes is that they can feel a little skittish, or at least lack a planted feel. By contrast,  the initial feeling of the new Addict RC was just how composed it felt. Given that the first 400 meters of the ride were down a 16% hill through quintessentially tight Spanish back streets I was impressed to feel at home so quickly.

Pressing on the pedals there is an immediacy to the effort being converted to forward motion. At lower power, the Addict RC is comfortable with no harshness transferred through the bars or saddle. I found that I was repeatedly jumping out of the saddle on short punchy rises to experience how the frame’s stiffness converts rider input to motion. Taking the Addict RC Ultimate into its home terrain, the bike demonstrated that there was more to it than just low weight that made it an exceptional climbing machine. The improved compliance gave me the feeling of isolating myself from the road in a way that allowed me to simply focus on applying power to the pedals.

Although the intentions of a lightweight bike are clearly aimed at helping to cheat gravity, where the Addict RC impressed me most was when heading back down. Descending on the Addict RC was a composed and predictable affair that took very little time to warm to. The combination of the wide-sitting 28 mm (quoted width) tyres that were fitted and the lowered bottom bracket meant that I could fully extract the grip that the Addict-exclusive Schwalbe Aerothan tyres offer. 

It will be interesting to get some time with a leg over the Addict RC Ultimate on less-favourable UK roads to see how it stacks up on broken and dirty asphalt. My assumption when riding the Addict was that the Syncross Capitol SL 40 mm wheels and the exclusive Schwalbe rubber were responsible for a large portion of the bike’s overall characteristics. I am looking forward to getting some time to put a set of more average wheels on the bike to try and quantify just how big the role of the wheels and tyres has on the Addict RC. 

Isolating the ride feel of the bike will be one of the first tests on the agenda. Swapping the Capital SL wheels out and testing the bike with a set of Rovals will shine some light on how much of the heavy lifting the wheelset is contributing to the overall feel of the bike. Back-to-back testing of the Addict RC against a Tarmac SL8 with each bike configured with both the Capital SLs and the Rovals should provide an objective comparison.

With the Contessa Programme ending, Suvi has also taken delivery of an Addict RC, allowing us to review the bike collaboratively. Across two different frame sizes from two different perspectives, keep an eye out in the coming months for this comprehensive review of the Ultimate model.

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