Pro bike: Aaron Gwin’s Specialized S-Works Demo 8

By Josh Patterson | Monday, March 25, 2013 11.44am

BikeRadar has been profiling Aaron Gwin’s bikes since he first turned pro in 2008. The 25-year-old World Cup downhill racer first rode for Yeti aboard a 303 Factory DH, then for Trek on a Session 88 and 9.9

Gwin has made some significant changes for the 2013 season, swapping Shimano for SRAM and leaving Trek for Specialized. We caught up with America's winningest male downhill racer in Boulder City, Nevada, following the first stop on USA Cycling Pro GRT.

New year, new team, new bike

Not surprisingly, Specialized’s top downhill racer is riding the company’s recently introduced flagship gravity bike, the S-Works Demo 8. New for 2013, it features a carbon front triangle mated to an aluminum rear end.

According to Specialized’s Sam Benedict, a carbon rear end is doable but the gains would be minimal and the price increase significant. “The gains you make in weight and stiffness are nowhere near that of the front triangle – we saved 500g on the front end alone,” he said of using carbon over aluminum.

The bike has short, 421mm chainstays and a low bottom bracket. An eccentric cam in the rear shock mount allows the rider to adjust the bottom bracket height from a low unsagged height of 338mm up to 353mm. The frame’s 1.5in head tube allows for AngleSet compatibility, should riders want to go slacker than the stock 64-degree head angle.

The s-works demo 8 has an carbon front triangle and an aluminum rear end: the s-works demo 8 has an carbon front triangle and an aluminum rear end

Lots of links: the upper stay and link control axle path while the lower stays drive the shock

Like the rest of the Demo 8 line, the S-Works frame features a low slung, centrally mounted rear shock to keep the center of gravity low. The frame has 200mm of rear suspension travel via Specialized’s Horst Link. 

The suspension arrangement looks more complicated than on the company’s other full suspension bikes. That’s due to the fact that the two pairs of 'seat stays' in the linkage have two very different roles: the upper stays and link control the axle path, while the lower stays drive the shock, controlling the spring rate. In addition to bolstering rear end stiffness, this setup allows Specialized’s engineers to tune spring rate and axle path independently of one another.

SRAM X0 – capable of more than XC and trail riding

In addition to switching bike brands, Gwin has swapped Shimano for SRAM. His bike was kitted out in full SRAM X0 in Nevada, with Renthal supplying the 36-tooth chainring and e*thireen’s LG1+ providing chain retention.

Gwin has also opted to run the lighter and still quite powerful X0 Trail brakes, rather than Avid’s downhill-specific Codes. The X0 Trail can be thought of as a scaled-down version of the Code; the four-piston calipers provide ample stopping power in a much lighter package.

SRAM's xo group handles brake and shift duties: sram's xo group handles brake and shift duties

Renthal also provides the handlebar and direct mount stem

Gwin still suspended by Fox

What hasn’t changed is Gwin’s suspension partner, Fox Racing Shox. Up front there’s what appears to be a prototype Fox 40 RAD (Racing Applications Development). We first spotted the air-sprung Fox 40 suspension forks last spring, at the first World Cup stop in Pietermaritzburg, South Africa.

The updated Fox 40 features a lighter chassis that, in conjunction with redesigned internals with a positive air cartridge, is said to be approximately a pound lighter than the 3.14kg (6.93lb) Fox 40 FIT RC2 fork. 

At the rear it appears Gwin is running Fox’s RC4 coil shock.

Aaron gwin took second at the first pro grt race of the season in boulder city, nevada: aaron gwin took second at the first pro grt race of the season in boulder city, nevada

The Demo family has evolved from a freeride platform to a collection of purebred World Cup race machines. We're interested to see how Gwin's input shapes the future of the range, as well as how his setup evolves throughout the 2013 season.  

Complete bike specification

Related links

  • Frame: Specialized S-Works Demo 8
  • Shock: Fox DHX RC4
  • Fork: Fox 40 RAD
  • Headset: Cane Creek Forty Series, integrated
  • Stem: Renthal Integra, 50mm
  • Handlebar: Renthal Fatbar, 780mm
  • Tape/grips: ODI Ruffian
  • Front brake: Avid X0 Trail, 200mm HS1 rotor
  • Rear brake: Avid X0 Trail,  200mm HS1 rotor
  • Rear derailleur: SRAM X0 Type 2, short cage
  • Shift levers: SRAM X0
  • Cassette: SRAM PC1070 chopped to 8-speed
  • Chain: SRAM 1091R
  • Crankset: SRAM X0 DH
  • Bottom bracket: SRAM PF30 DH, 83mm shell
  • Pedals: CrankBrothers Mallet DH
  • Rims: DT Swiss FR 600, 36-hole
  • Front hub: DT Swiss 240s, 110x20mm
  • Rear hub: DT Swiss 240s, 150x12mm
  • Tires: Specialized Butcher DH 26x2.5in
  • Saddle: SDG I-Fly
  • Seatpost: SDG I-Beam Micro Carbon

Critical measurements

  • Rider's height: 1.78m (5ft 10in)
  • Rider's weight: 74.8kg (165lb)
  • Seat tube length, c-t: 419mm
  • Head tube length: 112mm
  • Top tube length: 580mm
  • Head angle: 64 degrees
  • Seat tube angle (effective): 76 degrees
  • Wheelbase: 1,191mm
  • Chainstay length: 421mm

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