Scott’s new Scale 29er frame is guaranteed to weigh 949g, regardless of size (including disc mount and derailleur hanger but not seat collar); that’s less than many ProTour level road machines. It’s an incredible achievement that’s made even more impressive by the frame’s performance on the trail.
The Scott 29er makes an impression from the first pedal stroke. First off, its weight hovers around 20lb (9.07kg) with a high-end, but not exotic, build – SRAM XX group, Ritchey WCS cockpit, RockShox Reba 29 fork with 20mm through-axle and DT Swiss 240 level wheelset.
Going uphill the bike is impressive because of its light weight, head tube, bottom bracket and chainstay stiffness, and short 438mm chainstays. It begs to climb in the XX crankset’s 39T big chainring and easily scoots around 180-degree switchbacks.
Point the Scale 29er down the fall line and the benefit of the tapered head tube and 100mm-travel fork with 20mm axle (production versions will have either 15mm through-axles or 9mm open dropouts) are immediately apparent. You can push the bike through banked corners and it will pop out like a 26in-wheeled machine.
Scott USA’s Scale 29er RC frame is guaranteed to weigh less than 949g in any frame size
Scott have lowered the 26in-wheeled Scale’s bottom bracket for 2011, so that geometry with a 100mm fork is now the same as it used to be with an 80mm fork (use of a 100mm fork with the old frame geometry added 10mm to the bottom bracket height, which was not ideal), and they’ve matched this metric with the 29er.
They’ve also added 5mm to the head tube after finding that that everyone, including their World Cup racers, chose to use at least one spacer below their stems on the previous bike, suggesting that it was too short. The top of the 29er’s head tube is 42mm higher than the 26in bike. It has a 10mm longer top tube, which is offset by a shorter stem. This produces the same overall reach but with better downhill handling characteristics.
Scale’s 29er geometry makes for an easy transition and no weird handling issues; key measurements include a 69.5-degree head angle, 72.5-degree seat angle and 310mm/12.2in bottom bracket height. Since the geo seems spot-on, its easy to move onto the most impressive feature built into this frame – the compliance engineered into the rear triangle via a flexing seatstay design similar to the latest CR1 road bike. The bike has a measureable amount of vertical flex, which Scott claims at 4mm.
The bike’s seatstays are engineered to flex vertically by 4mm
We cannot verify the amount the amount, but the rear end does flex noticeably in the vertical plane. While it’s not enough to make a difference when jamming on really bumpy flat trails – you still have to stand up, unlike on a good full-suspension bike – the design does take the edge off rough descents. The bike is smoother and big hits are noticeably reduced.
“It’s not enough to be just lightweight, it’s not enough to be just stiff – we needed to design some comfort into the bike,” said Joe Higgins, one of Scott USA’s in-house engineers. “The SwissPower team say they’re happy on most of the World Cup courses on a hardtail but they do want some sort of shock absorption, and the approach we’ve taken is to design flex into the seatstays.”
The flattened oval seatstays with a specific carbon layup that’s engineered to flex are the key component to the design. Paired with stiff chainstays, most of the movement comes over the middle two-thirds of the seatstays. The Scale is equipped with a 34.9mm seatpost because the SwissPower riders want to minimise movement between their butts and feet.
With extensive experience on many equivalent bikes from Scott’s competitors, our first ride on the Scale 29 was impressive. The bike is excellently executed in terms of both geometry and ride quality. Add to that the fact that it’s a clear leader in terms of weight and it will be impossible for those looking for the ultimate hardtail to ignore it.
Construction: Moulding efficiencies make it lighter
The ride quality is the best performance feature of the new Scale 29er, but its weight will be the most talked about. The top-end frame built with HMX carbon fibre is guaranteed to not weigh more than 949g, no matter the size, and could be as light as 929g. The Pro level frame built with lower modulus HMF fibre is said to weigh around 100g more.
In production, the HMX Scale 29er will be branded as Scale RC not 949
The Scale 29er shares its design with a 26in frame that’s guaranteed to weigh less than 899g. They’re both cross-country racing rigs, but the 949 is much more versatile for average riders than the 899, which is most at home on the World Cup race course – it is newly built for the world champion, after all.
In shaving weight Scott didn’t cut corners on performance. The new bike is said to be stiffer, laterally, in key areas, including steering and pedalling. The previous Scale was made using the CR1 tube-to-tube construction process; the new bike uses Scott’s proprietary IMP co-moulding process. This combines an outer mould with a secret internal mould to create an inside surface that’s smooth, clean and free of the wrinkles that trap excess resin and thus add weight.
Comparison between the old Scale’s CR1 head tube and the one-piece IMP moulded model
The front end uses an IMP3 mould, in which the frame’s tapered head tube, top tube and down tube are moulded as one piece. Both pedalling and steering stiffness are bolstered due to the ability to match a larger down tube to the larger lower head tube. The IMP moulded PF92 press-fit bottom bracket shell and seat tube also add pedalling stiffness.
Finally, and possibly the most impressive technological development, is the IMP moulded rear chain- and seatstay combination. Despite their tuned vertical compliance, Scott claim lateral stiffness of the new stays is increased by 10 percent, while they lose 25g when compared to the previous design. The three IMP components (front end, BB shell and seat tube, and stays) are joined using the CR1 tube-to-tube process.
The full-carbon tubular stays include post mounts for a 160mm disc brake. Why not a 140mm rotor to save weight? Scott couldn’t easily move the 140mm mount back far enough without negatively affecting the stays’ compliance or adding what they considered unnecessary weight.
The Scale uses a direct post mount for the rear brake, which will not accept a 140mm rotor
New construction processes serve to eliminate almost all metal from the new Scale frame. All that remains is the two threaded post mount brake attachment inserts, which are now located on the chainstays, and a single threaded hole for a chain watcher.
The dropouts, press-fit bottom bracket and head tube are all carbon, with the latter accepting zero stack style press-in inserts. By comparison, the previous generation Scale, only available with 26in wheels, had aluminium dropouts, disc brake mount (IS) and 73mm bottom bracket shell.
Removing metal removes weight, both through the metal itself and because moulding metal into a frame requires that the carbon bonding surfaces be reinforced
All Scale 29er frames use the PF92 press-fit bottom bracket standard, while the 26in models are split between BB30PF (BB30 crank) and PF92 (lower tier models). PF92 allows the use of most 24mm cranks and offers a wider chainstay stance, which is critical for tyre clearance on the 29er and makes the use of the 438mm chainstays possible.
The Scale 29er comes with a PF92 BB shell; launch frames were incorrectly labelled PF30
The new 29er will be available in sizes medium to extra-large, but not in small because Scott don’t believe big wheels benefit smaller riders. Based on an identical specification, Scott claim that the 29in-wheeled bike adds 700g over the standard model; all but 150g comes from the components, and much of that weight comes from wheels and rubber.
The top-of-the-line Scale 29 RC costs US$6299.99 with a Fox F29 Remote fork, SRAM XX group and DT Swiss XR-29 wheelset. This machine is roughly equivalent to the bike we rode at Scott’s launch, so it can be expected to weigh around 20lb.
The Scale 29 Pro sits a step down, sporting the same frame design but made from lower modulus HMF carbon, which adds roughly 100g. At $2399.99 it comes with a RockShox Reba 29 SL fork and mix of SRAM X7/X9 and Shimano components. Scott will sell the high modulus HMX carbon frame alone for $1899.99.