Scott has a long history of producing carbon fibre frames – Jurgen Sprich became European Downhill Champion on a Scott carbon fibre DH bike in 1993. Over the years the Scott engineers have been refining and developing their design and production methods, coming up with groundbreaking and popular bikes like the Endorphin and Strike.
With the launch of the 895g CR1 carbon fibre road frame and Genius range of full-suspension bikes last year, it was only a matter of time before the two lines converged and for 2005 there’s a full range of CR1 Genius bikes and an all-new ultralight hardtail conceived to help team rider Thomas Frischnechkt to Olympic gold in Athens later this year.
The CR1 name (it stands for “Carbon for Racing”) has been appropriated as the umbrella name for Scott’s carbon fibre technology, but what makes it different? For a start, the actual fibres themselves are a particularly high-performance example of the breed, with 28 times the tensile strength of a quality chromoly steel and between 30 and 50% less elongation. The key difference, though, is the way that the fibres are used to make a frame.
Generally, carbon fibre bike frames are either moulded monococques, with the whole frame made in one piece, or they’re assembled from tubes bonded to lugs. The first way usually looks great, with smooth, organic lines, but you have to make a big and expensive mould for each size frame and it can be difficult to realise a couple of the key advantages of carbon fibre – the ability to vary the construction of each part of the frame to give different properties and the very low potential weight. The tubes-and-lugs approach is a better bet from the point of view of varying the tube construction, but you’re adding material where the tubes and lugs overlap which adds weight.
In contrast, CR1 are assembled in a similar fashion to welded metal frames. Each tube is constructed individually, with different types of carbon fibre, varying weaves, thicknesses and orientations along its length to give it just the right stiffness and strength characteristics at minimum weight. Up to five different types of carbon fibre are used in a frame, and they’re pre-stretched within the tube so the fibres are already under tension for extra stiffness. It’s like a tightly-laced wheel compared to a loose, floppy one. By fiddling around with the carbon fibre in the tubes like this, Scott can do clever things like make round tubes that are stiff in torsion and laterally, but relatively flexible vertically.
The tubes are shaped at the ends to fit together, just like metal frame tubes. Then some joining magic happens – the tubes are “weld-glued” together in what’s informatively described as a “proprietary process”. Essentially the tubes are bonded together with high-tech glue “fillets”, giving smooth lines but, says Scott, higher strength than a monococque construction. If it’s as good as claimed, it’s no wonder that Scott remains tight-lipped about the details.
The all-new Scale CR1 hardtail frame is probably the most dramatic example of the potential of Scott’s technology. This is the bike that Thomas Frischknechkt will race in the Athens Olympics, and Scott has engineered a frame that promises stiffness for optimum power transmission combined with a comfortable ride. The engineers are sufficiently confident in the shock-absorbing properties of their tubes that they’ve used an oversized seat tube to boost the stiffness of the front end and put a big 31.6mm seatpost in it – there’s not going to be much flex in that, so it’s all down to the frame.
The most impressive thing about the Scale, though, is its weight (and in case you were wondering, it’s not called Scale because of the minimal impact it makes on said measuring equipment – it’s Scale as in “scale the mountain”). Picking up a bare Scale frame messes with your head – it’s this big, fat-tubed thing but it feels like it weighs nothing at all. It does weigh something, of course, but not much – at 970g this is the first sub-1kg mountain bike frame that we’ve heard of. Yes, you read that right – 970g, or 2.1lb in old money. Or to put it another way, about two-thirds of the weight of what most people would consider a very light frame.
Built up in Limited spec – SID forks, XTR transmission, FSA carbon cranks, DT Swiss wheels, Avid brakes, Ti Eggbeaters – a whole bike comes in at just 7.7kg (16.9lb), which would be entirely respectable for a high-end road bike let alone a hardtail MTB with a full complement of gears.
Similarly impressive feats of weight reduction have been achieved with the Genius full suspension bikes. The 125mm travel MC comes in at 2.25kg (4.9lb) for frame and shock, and a 11.4kg (25.1lb) complete bike in Limited spec (Fox TALAS fork, XTR, Mavic Crossmax wheels). The shorter-travel RC is lighter still – 2.1kg (4.7lb) frame only, 10.4kg (22.9lb) as a complete bike. Each bike will be available in a range of specifications at lower price points – UK pricing is yet to be confirmed but expect something around the four grand mark for the CR1 MC Limited.
The Genius suspension design is geometrically unchanged from the current bikes, but a bit of tinkering has gone on with Scott’s own three-position pull-shock. For those not familiar with the unit, it offers a “fully open” All Travel mode, a stiffer Traction mode with more platform damping and a locked out mode, controlled by a bar-mounted lever. The shock’s been revalved for 2005 with a more marked difference between All Travel and Traction modes. Both are said to be plusher, but All Travel is, er, more plusher than Traction mode.
Brief riding impressions around some spectacular trails in the Swiss Alps (part of Frischknechkt’s high-altitude training ground) showed the CR1 MC to be quite an inspiring machine. The geometry is unchanged from the aluminium bikes, and the characteristically Scott short, steep, forward-set riding position is something of an acquired taste, but once we’d got the hang of things (and swapped the stem for something a little less tiller-like) the light weight of the bike really made a difference, with line changes just being a flick of the wrists and ankles away and every little root and rock becoming launch pads if you wanted them to be.
As ever, the verdict will have to wait until we can get the bikes on to home turf but Scott’s carbon fibre technology certainly turns out a spectacularly light bike…