Scott’s new Addict RC weighs 5.9 kilos in its top build with a frame weight of just 640g, achieved thanks to a new process that the Swiss brand says is “unique in the cycling industry and only applicable if the frame design is tailor made for this manufacturing method”.
According to Scott, the Polypropylene Molding Core technique ensures a high-precision moulding of inner surfaces and transition zones, which leaves the inside of the frame clean without voids, wrinkles or excess resin, leaving only what’s necessary for stiffness and strength. Paired with optimised tube shapes that eliminate additional reinforcements and unnecessary filler material, with wall thickness reduced in some areas to 0.6mm, Scott says the result is an “ultra-light frame without compromise”.
As well as reducing the frame weight in order to bring the new bike in under six kilos, Scott shaved grammes from other areas of the ‘frame kit’ – the frame, fork, seatpost and hardware required for assembly – and claims a 300g reduction in weight compared to the frame kit of its predecessor.
The new Addict RC has clearance for 34mm tyres, a move that has necessitated a reworking of the geometry. This includes lowering the bottom bracket to equalise centre of gravity, shifting the seat tube forward 5mm to make more space for the bigger rear tyre, increasing fork rake to achieve the same trail values as previously – all the while keeping rider contacts points the same as before, and crucially aligning with the Foil RC’s geometry, the aero bike used by its pro teams so that riders can switch quickly from one to the other.
Scott’s lead road bike engineer, Max Koenen, explained to Rouleur how his team pushed the boundaries of modern carbon manufacturing, but also why 5.9 kilogrammes is an auspicious number in the Swiss brand’s story. “We were digging into the history of Scott’s road bikes, the Addict, and we found the original Addict Limited from 2008, which came in at 5.9 kilogrammes. This was a frame with an integrated seat mast which had a weight of 790g – pretty spectacular back then. It also had a nice racing history: Mark Cavendish used it for his Tour de France final stage win on the Champs-Elysées in 2010. So we had our target right there.”
However, Koenen says, despite 16 years of road bike evolution, it would be a challenge to make a modern bike as light as that. “This original 2008 bike was mostly determined by its components, which are outdated by modern standards. It had tubular rim brake wheels, rim brakes, no electronic shifting or integration… In 2024 bikes have specifications that are a must-have, but which add weight.”
Koenen continues: “So we defined our development targets for this bike. Number one was clearly the weight. We calculated that to achieve this goal of under six kilogrammes we needed a frame under 600g [size medium, unpainted] in the top version. Among our competitors there is barely anyone under 600g and certainly with a frame which is racing compatible in terms of stiffness, so it would be a challenge.
“The Addict RC is also a race bike used by pros in the WorldTour, which means we cannot fully ignore aerodynamics [Scott also has the Foil RC aero bike]. Aerodynamic improvement was clearly also one of our top targets compared to the previous generation.
“The comfort topic is everywhere at the moment, so we wanted to increase tyre clearance to 34mm and improve comfort of the frame itself, too.
“Last but not least, the geometry has to be racing. RC stands for ‘Racing Concept’ so that means the bike-fitting geometry for the rider should be very aggressive, low and long as our pro riders request, but also the bike should be agile and nimble. With the bigger tyre clearance we would have to make some adaptations to avoid it becoming too lazy or sluggish. The goal was that the new bike should feel similar in handling to the old bike but with increased comfort and lower rolling resistance and better grip of the bigger tyres.”
Next, Koenen and his team had to decide how to actually achieve their aims. “Often when we develop new bikes there are some restrictions: we need to use the same axles or the same steerer diameter or the old bar and stem needs to fit… but it became pretty clear early on that if we wanted to achieve this goal of getting a bike under six kilogrammes we needed to start thinking everything from zero and not in terms of backwards compatibility.”
First came the geometry – adapting the frame so that with bigger tyres it would still handle like a race bike with the rider contact points in the same place.
Then came the weight. “We took our time to go to the factory, observe the way the previous Addict RC was produced, searching for possibilities to get rid of everything that was there just as a filling material, design edges or features and sometimes manufacturing methods that were costing us weight because we weren’t achieving a high enough precision.
“The polypropylene moulding core process is used in the bicycle industry mostly by e-bikes where you want to have a very precise inner shape of the frame because there’s the motor and the battery inside, and it’s also used on our high-end mountain bikes to get as much resin out of the frame as possible and only leave behind what is needed,” he explains. “If we made a frame that looked the same but without the polypropylene mandrel it would be at least 50 to 100g heavier. But on the fork it’s certain that we saved around 40g and for sure it’s the reason why we have the lightest fork on the market at 270g, even though our fork has aerodynamic blades and much more volume. And we still have a high wall thickness for safety where the bearing seat is and also where the hole where the cable passes through.”
Contributing to the reduced frame kit weight are a new Sycros integrated cockpit that Scott says is 40g lighter for the same strength and stiffness, and a new seatpost that is a claimed 10% lighter and 30% more comfortable.
With the new Addict RC weighing 5.9kg in its top spec with SRAM Red AXS and Syncos Capital SL wheels, there’s no redundant resin left inside the tubes, it’s well below the UCI minimum weight limit of 6.8kg but, explains Koenen, the Addict RC was not designed only for professional racing. “It’s slightly unique what we’re doing now. Most of our competitors are unifying their competition race bikes but we decided not to – and one of the reasons was because the Foil RC is pretty light, close to the 6.8kg UCI rule, so the pro teams on flat stages will always go for the aerodynamic bike. But we saw room to make a lightweight bike that is a bit more for the consumer and the people not bound by the 6.8kg rule, so that’s why we went spectacular with the weight numbers.”
Ride impressions
Who doesn’t love a light bike? Well, the Scott Addict RC is a really light bike and I’ll say from the outset that I absolutely love it. The ride is as spectacular as the weight numbers.
I could put it down to the power of suggestion but I had the sensation that I could feel the ultra-smooth insides of the frame tubes as I pedalled it – the ride quality really is that flawless. I knew how good this bike was going to be just from the sound it made when I clipped in – sometimes you just know. Changing gear with SRAM Red AXS was a pure sensory experience – the plush precision of the transmission, the muted retort of the smaller sprocket engaging and the surge thanks to the sheer lightness of the bike.
You could say Scott slightly cheated by speccing the awe-inspiring Syncros Capital SL wheels with the top Addict RC Ultimate build: these weigh just 1,170 grammes in this 40mm version thanks to a one-piece carbon design that moulds the rim, spokes and hub flange together, resulting in wheels that are unbelievably responsive. But they’re actually the perfect match for the Addict RC Ultimate frame. Both are about lightness and speed and they complement each other in a way that Scott must be very proud of. And, although they’re impressively silent like the rest of the bike, when they get to 30mph on smooth tarmac they start to sing.
Very light bikes can feel brittle sometimes, but the Addict RC has a springiness with its rigidity. No doubt some of this can be attributed to bigger tyres, but everything in this build works together so well that it’s almost impossible to attribute the various elements of the ride quality to individual components. The seatpost flexes, the spokes are moulded with a curvature designed to allow them to deflect slightly, the front end feels super direct without transmitting vibrations… it all comes together to make what must be the best lightweight race bike of the disc-brake era. You have to applaud Scott’s decision not to unify its aero and lightweight race bikes because this uncompromising new bike is like nothing else I’ve ridden so far.
Product range
The Addict RC will come in different models, all with Scott’s HMX carbon construction (HMX-SL for the RC Ultimate). According to Scott, even the RC30 model, with Shimano 105 Di2 weighs under 8kg. The flagship RC Ultimate model is priced at £12,799/$14,999 and the ‘entry-level’ £4,899/$4,999.
Check out Scott's website for all the details
