(NOTE: Our review as originally written is below. But we've posted a late add, as we've discovered a bit of functionality about this bike of which we were not aware when we edited our road test just a few weeks prior.)
If you own or manage a bike shop not currently carrying the Scott brand, you immediately point to that seat mast and imagine this an impediment to the sales of the Plasmas.
But in the course of my investigation of this bike, and to my surprise, I have not found retailer-one who considers this an issue. Cutting that seat mast to the proper size is not much different than cutting a fork steerer, except you don't have to be quite as precise (a good thing), and you don't get to use a miter block (a less-good thing).
The Plasma is ridden by pro triathletes Cameron Brown and Ain-Alar Juhanson. Brown has been an ultra-distance star for most of the last two decades and the better triathlete of the two, but Juhanson is an Estonian beast who is Scott's answer to Bjorn Andersson's bike power and Viggo Mortenson's hunk power. A pic of Juhanson aboard his Plasma in profile will serve as backdrop for the geometric elements of this discussion, as will a page of photos of Brown aboard his bike. In both cases these men are riding with Visiontech aerobars, a subject to which we'll return later.
The Plasma is a single frame model that is available with different groupkits, granting the user a variety of pricepoints from which to choose. The bike we rode was the Plasma Pro, which sells for anywhere between $3700 and $4200, depending on the retailer (we see the Plasma Pro at that lower price online here). The kit is largely Shimano Ultegra, with Mavic Cosmic Elite wheels, Profile Design Cobra T2+ bars and QS2 brake levers. The saddle is a ready-to-ride Fizik Arione Tri 2.
The frame, designed in conjunction with ex-pro road, MTB and multisport cyclist Steve Larsen, is the sizzle here. About that seat mast: You cut it to suit. No seat post here. There's an aluminum cap that incorporates the seat post hardware, and the cap tightens onto the mitered seat mast. If you err and cut the seat mast a bit short, not to worry, you can suspend that cap a bit above the mitered end of the seat mast.
In a way, it's not unlike cutting the aero-shaped seat post on a Kuota Kalibur or any other such bike (you also don't get to use a miter block when cutting those either). In the case of Kuota's seat post, or Scott's seat mast, you wrap some tape around the thing so you don't get frayed ends, and hack away with your 32-teeth-per-inch saw, just like cutting a carbon steerer. But wait! Scott makes it a bit easier, by including with every bike a guide that allows the mast to be cut precisely crosswise (the next thing to a miter block).
The seat post cap grants you about 2cm of wiggle room, that is, you can cut the seat mast as much as 2cm too short and the post cap can successfully and safely be raised that far above the miter. If you manage to cut it too short anyway, there is a second seat post cap that's longer, and fixes your mistake.
The seat post hardware is the easiest I've so far seen when it comes to getting the saddle tilt correct. It's two bolts, and the front bolt acts as a pivot around which the saddle rotates, that is, the saddle tilts up or down around that pivot, and the rear bolt locks the saddle down.
Perhaps some bike boxes might not easily accept a Plasma and its long seat mast, but I don't perceive that as a major issue. Big Juhanson seems to get his bike from continent to continent. What is the point of that long mast, anyway? Weight. The frame is quite light for one with so much surface area, and it's that long seat mast that accounts for a lot of the weight savings.
The Dropouts are not rear entry, so you can't microadjust the distance between the carved out seat tube and the rear wheel. But, a 23mm-wide clincher was no problem during my test, that is, it was quite close to the seat tube "fairing" but not too close. I do have a set of Reynolds road race wheels on which are mounted some 25mm Continental tubulars. Any wheels with those tires would be a problem in this bike. But who rides them but me? Not many. Just the same, consider what your favored tires are when riding a frame featuring a faired rear wheel and a horizontal dropout.
The frame is plenty stiff enough, as this new generation of carbon monocoques tend to be. It's not wholly different than riding a QR Lucero or Kuota Kalibur. Unlike the aero bikes of 15 years ago, where you had to be careful the tires didn't rub against both chainstays when you got out of the saddle, the Plasma was rock solid.
One cannot gauge, with any surety, the aerodynamic efficacy of frame shapes by looking at them. Scott's bike designers spent time in the wind tunnel during the Plasma's development, but that's no guarantee that it's slipperier than another frame in its competitive set. Certain of its "tube" profiles are considerably wider than those of other bikes, in particular the down tube, which is about 35mm wide compared to that of Cervelo's P3C. Neuchatel resident Gerard Vroomen would sooner swallow a Swiss cow bell than produce a Cervelo with a main tube diameter greater than 30mm. But the wind hits the bike before it gets to the down tube, and that tube also hits the wind at an angle. There is just no way to warranty, by inspection, the aerodynamic value of this frame. Anyone who attempts this is silly. You place faith in the goodwill and talent of its designers, or withhold such faith, as you choose.
But we can make demonstrative statements about the Plasma's geometry. You can lump today's tri and TT bikes into three categories. If you're Faris Al Sultan, Normann Stadler, Tim DeBoom, Torbjorn Sindballe, Bjorn Andersson, and others, you tend to ride quite steep. In this case, a set of bikes has been geometrically built to accommodate your style of riding. It would be freak luck if, as a pro athlete, this has been impactful on your choice of bike sponsor -- the size of the check is as important as the size of the head tube when you're deciding what bike is best for you. Nevertheless, these riders above are a good thematic fit with the 2007 geometries found in Giant's Trinity Alliance, all of Felt's bikes, QR's Kilo and Tequilo, Trek's new Equinoxes, and all of Cervelo's Bikes.
Next you have Kestrel's Airfoil Pro, the carbon QRs, Kuota's Kalibur, and the Argon-18 Mercury. These and other bikes like them are slightly shallower in their seat angles, but still with fairly low front ends and reasonably long front-centers that accept a steeper rider. Scott's Plasma, the Cannondales, Kuota's K-factor, have those same in-between seat angles, but with taller head tubes.
Next are bikes with a Euro flavor, and the TT bikes made by Pinarello, Orbea, Time and Look are emblematic of short front-centers, shallow seat angles and short head tubes. These bikes would be difficult for steep riders such as Stadler, Sindballe, Zabriskie and Cancellara, to adapt to.
The Plasma, as we see, is geometrically in between the Eurostyle frames and those built in the U.S. or North American tradition. This Plasma-style geometry parallels nicely the sort of position you'd see ridden by pro athletes with the first names of Chris or Cam (Legh, McCormack, Lieto, Widoff or Brown). These riders all ride shallower than those mentioned above, and Cam Brown is a good thematic fit for Scott.
If your first name is Xavier, is there a workaround for you? Can you still ride a Plasma? There is a reliable test: Determine your "fit coordinates" -- the placement of your saddle, and your aerobar's armrests, in relation to your bottom bracket. These are immutable points that relate to how you ride your bike, any bike, most effectively. Even if your name isn't Chris or Cameron (or Carl or Clive), perhaps you ride like one of them. In this case, a Plasma may be for you.
Whether the Plasma is made with a geometry that matches your riding style is one of three hurdles to clear before you can make a rational decision in favor of this bike. The second has to do with your pedaling technique. This bike has a top tube flattened in a horizontal plane. If you ride with your knees trending inward at top-dead-center, you may find this bike's top tube a knee-biter. Of course, best is to spend $25 and have your LBS varus wedge your cleats, which will grant your legs a truer track as they circle the cranks, alleviating any issue of top tube clearance and giving you a better pedal stroke.
The third issue with which you must deal is the spec problem associated with this bike. Scott simply blew the aerobar spec. This bike should never have had Profile T2 Cobras or Pluses mounted atop its frame. As noted above, Cam Brown and Ain-Alar Juhanson ride Visiontechs, and this is the proper aerobar for the Plasma. The head tube on the Plasma is simply too tall for the high-profile armrests that the Profile bars feature.
Does this mean Profiles are a problem? Not in the least! With no fanfare, Cervelo quietly changed from Visiontech to this same Profile aerobar last year, precisely for the reverse reason they are a bad spec for Scott. While the Visions remain the spec on Cervelo's P3C, the higher-elevation Profiles are spec'd on the P2C and P2SL in order to accommodate the positions Cervelo perceives are more typically ridden by mid-packers or BOPers.
Simply put, the Plasma is a very nice frame, but its customers who are students of optimized tri bike fit will almost certainly have to immediately -- at the point of purchase -- swap out the OE Profiles for aftermarket low-profile aerobars, like Visiontech or Hed.
The other stereotypical customer for a bike with the Plasma's geometry is the long-legged, short-torsoed rider who'll ride a bit steeper than the frame's 76-degree seat angle, and who'll need the taller head tube and shorter cockpit associated with an artificially steepened bike. This would become a significant sector for Scott if it does in the future what I shall recommend in the next paragraph.
As noted, Scott has already made a longer seat post cap for those who are a bit hasty and aggressive with their hack saws, and cut too much off (you can subtract from that carbon seat mast with your saw, but you can't add to it). Since Scott is already engaged in making seat post caps it did not originally anticipate making, why not make one that sets the post hardware forward of its original position? Orbea and Kuota make a second, steeper seat post for their bikes. Why not Scott as well? (Except it's a steeper seat cap instead of a steeper seat post.)
This is not to say Scott made a mistake when choosing its 76-degree seat angle, it rather drew a line in the sand and staked a position for itself. But the position staked makes this bike less optimized for those who do ride steep. If you make that forward seat post cap, you're adding to the audience who might like the Plasma, but who can't get the saddle forward enough for their liking. Keep in mind, however, that the steeper you artificially make the bike by moving the saddle forward via an aftermarket "steepener," the more you need to be of the long-legged sort, lest you ride the bike with an overlong stem.
Make no mistake, the Scott Plasma is built in a way quite different from other tri bikes. If you're wavering between a Cervelo P2C and Felt B2, or between an S22 and a QR Tequilo, you're on the right track, that is, you're deciding between two geometrically like bikes. If you're undecided between this Scott Plasma Pro and a Cervelo P3C, you have yet to answer some basic questions about how you yourself ride a bike. Answer those questions first, using a protocol invested with more precision than considering the first letter of your first name. If the Plasma matches your riding style, it is the equal or better of most of the bikes in its category.
LATE ADD
We've been fooling around with our Scott Plasma after having published our write-up, and we've discovered some new functionality, aided by one of our loyal Slowtwitch readers (who showed us a little trick).
We always knew that the Plasma got us a little steeper than we thought we'd be able to get. In fact, our own measuring apparatus says this 76-degree frame in 56cm we got sent is actually closer to 77 degrees. Furthermore, the seat clamp hardware atop the seat mast -- of which we were an instant fan, with its ease of use -- is generous in its allowance of forward saddle movement.
Then we discovered, with the help of a Slowtwitch reader, a nifty trick. By swapping the left and right seat post hardware, you get an extra centimeter of forward saddle adjustability (as shown in the adjacent photos).
All this means that the Plasma I rode, at 79cm of seat height (bottom bracket to saddle top), allows for the saddle nose to be 2cm in front of the BB axle. That putative 76-degree frame is therefore adjustable to right at 80 degrees, BB to the middle of the saddle's rails.
This is quite unexpected, and I can't think of another 76-degree bike with a single-position proprietary seat post allowing this much forward adjustability.
