Scott Plasma Limited
Reviewed by Coach Matt Russ
In the 90's it was all about weight. Manufacturers struggled to come out with the lightest bikes because the lightest bikes sold the best. Aerodynamics was not ignored but manufacturers produced what cyclists wanted; very light bikes. The demand led to a revolution in material manipulation and shaping technology. It is easy to pick up a bike and feel how amazingly little it weighs, but its aerodynamics are far more subtle. You can't see or feel a low drag coefficient (unless in a wind tunnel). Once bikes started getting consistently around the 16-17 pound mark, and the sport of triathlon started its explosive growth, the focus turned towards more aero tri bikes. Aerodynamics is as much, or more, of a factor in producing a fast bike, and consumers began to wise up. Now we have dimpled water bottles.
In order to reduce drag complex monocoque frames with aerodynamically shaped and wind tunnel tested structures were produced. The downside was that this process required more frame materials, thus the very aero frames were traditionally much heavier than a road frame with round tubing. On a flat course at high speeds as in a time trial these bikes were much faster, but once speed dropped and you had to climb they were pigs. For triathletes that usually face a varied or even hilly course it was an either or situation. Either a light bike that climbs or an aero bike that produces less drag. The real challenge was producing a light aero bike.
Enter the Scott Plasma Limited. This bike is about as aero as they come and it weighs in at an amazing 15.4 pounds. New carbon fiber technology and manufacturing techniques have entered the bike market in the last few years, but I don't know how they pulled this one off. Actually there are a few design elements that really cut the weight, mainly the absence of a traditional seat post. This is an area that traditionally required double materials. In it's place is a solid beam with a movable seat cap on top. This allows for a relatively small range of adjustment; if you cut that beam you better make sure it is right. This also limits your ability to sell the bike if the purchaser is not within a similar size range. The other problem the design creates is in transportation and shipping. The Plasma does not fit in some bike carrier boxes, and if you are over a size medium will probably require removal of the bottom bracket. If you are not adept at doing your own mechanical work and travel to races, this is a serious consideration. You can already see a lot of other brands picking up on the design, or a variation of it, but with more consideration to travel. I have to say it works better than a lot of the aero seat posts I have come across. Because of the air foil shape only a very small amount of torque on the clamping bolts is allowed. If you stay within the torque limits the seat post may begin to slide down, especially if you are a heavy rider (Cervelo P3 carbon). If you tighten the bolts further you risk a cracked frame. I had one athlete so frustrated with his sliding seat post he had carbon fiber stops made for his bike. The Scott design does not seem to have any major issues, although the seat tilt mechanism did slip several times after hard bumps.
Componentry is all top shelf as you would expect; Durace throughout. The Zipp 606 is the wheel set of choice right now and they even sweeten these up with DT Swiss hubs versus the stock Zipp hub. My only consideration is the Profile aero bars. It is a good, solid, light, and comfortable set up. The adjustment is very good. But on a top shelf bike like the Plasma I would expect a fully integrated aerobar versus a clip on. It just is not clean enough for the rest of the bike, with new models in the same price range coming up with a much more integrated design (Felt DA, Specialized Transition).
The problem with monocoque frames is they are very expensive to produce. Some manufacturers cut corners by producing a smaller number of sizes (S,M,L)and making up for the gaps with a wider range of components. Unfortunately this leaves a lot of cyclists within those gaps. The Scott has 5 sizes from XS to XL so most should be able to find a bike that fits them.
The ride is very stiff, although I am a smaller rider. It was noticeably stiffer than my Giant road bike which surprised me. I thought a bike this light would have some flex, but I could not detect any major flex around the bottom bracket.
Matt Russ has coached and trained elite athletes from around the country and internationally for over ten years. He currently holds expert licenses from
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