Pro bike: Carl Decker’s Giant XtC Composite 29er

New carbon race machine for Giant’s resident big-wheel aficionado

Giant Factory Off-Road Team member Carl Decker raced last year's Sea Otter Classic on a prototype 29in-wheeled version of the company’s Anthem X and he's followed suit this year on another big-wheeled prototype, the XtC Composite 29er.

Decker received the one-off frame this January, though he admitted he hadn't ridden it much before the team camp in sunny Santa Barbara, California in late March. "I’ve been in ski mode basically until now, short of about one ride a week on it," he said.

Nevertheless, Decker hasn't wasted much time getting the XtC on a race course, first using it at the Sea Otter Classic just a few weeks later, then again at the Whiskey Off Road in Arizona. "It'll probably be my short-track bike of choice," he said. "It's also going to be a great Leadville 100 bike. But I’ll still race the Anthem X 29er quite a bit this year and I have a Reign X I may even race some burlier Super Ds on."

Decker will add the new Giant XtC Composite 29er to his current Anthem X 29 and Reign X for this season's races

Decker’s bike is a true prototype and not just an early production sample – at least for now. While a production version will be released later this year, Decker’s test mule uses an experimental carbon fiber layup schedule that’s 80g lighter than what the public will get but slightly less tolerant of crash damage, too – something Giant aren't willing to compromise on for general users.

"The Giant XtC Composite 29er is more of a pricepoint bike and uses our Composite technology, versus our higher-end Advanced or Advanced SL carbon," said Giant global marketing director Andrew Juskaitis. "Production added about 50g to ensure strength where we felt the frame needed it."

Decker’s prototype shares most of its features with the production version, including the Overdrive tapered head tube and extra-wide Powercore press-fit bottom bracket shell, which are joined together with Giant's rectangular-profile MegaDrive down tube. "It turned out so wide that we had to make the down tube asymmetrical to provide chainring clearance on the drive side," said Juskaitis.

The enormous, rectangular-profile, asymmetrical down tube suggests excellent front triangle and bottom bracket stiffness.  And as a bonus, it looks like it’ll make for a great built-in front mudguard, too

Add to the asymmetrical design a pair of offset chainstays, twisted seatstays and a kinked seat tube that allows for a shorter rear end. Comparing the prototype to the production sample in terms of general design, they both look quite similar. Of course, paint, decals and polish can hide quite a bit, but one visible variation is a slightly less drastic asymmetry in the chainstays on the production version. The down tube is a bit different as well.

"The driveside chainstay on Carl’s proto ‘dips’ down about 15mm more than the production version — an early attempt at chain clearance which we decided wasn’t necessary," said Juskaitis, accounting for the remaining 30g differential between the production and prototype frames. "Carl’s MegaDrive down tube is even more offset (to non-driveside) than the production version. We were able to equalize the production down tube a bit more although it’s still slightly offset."

Decker’s bike is impressively light at just 10.04kg (22.13lb) with alloy training wheels and pedals. While much of that is likely due to the new frame, there's also an almost entirely new build kit. "For the past few seasons we were always told that our new bikes would be lighter than last year’s bikes before we got them, only to find out that they always weighed almost exactly the same when they got built up," said Decker. "This year, our bikes are legitimately lighter by at least a pound across the board."

Shaping on the tapered head tube is similar to Giant's TCR road range

Switching over to SRAM's XX group with a 2x10 drivetrain played a key role in reducing weight. For Decker, it also switched up his gear ratio from the previous 3x9 he was used to. "The crossover gear with 2x10 is awesome," Decker told BikeRadar. "At first I was a bit nervous as I'm a sewing machine guy when it comes to pedaling, but so far it's been great. There are a few race courses I'm nervous about but I’m hoping it'll just make me go faster on those climbs."

Reducing his prototype's mass even more will be DT Swiss's new XRC 950 T carbon tubular 29er wheels – said to weigh just 1,200g per set. In previous years, Decker has been known to cut his own tires to decrease rolling resistance and improve traction but this time around, Schwalbe will be doing the work for him, custom tuning tires to his preferences.

"Schwalbe have tons of SKUs," Decker said. "I think they offer three or four cross-country tires in three different compounds and several different widths. And they’re offering us custom tires with our choice of tread pattern, compound, and width, too." With Decker racing so many disciplines this year and knowing how particular he is with tires, we’ll be surprised if he’s not on a special set of Schwalbes for each major race this season.

Opting for a little less weight than a lock-on grip, Decker runs ODI Ruffians with the flanges removed and moto-style wires to keep them tight

Rounding out Decker’s prototype setup are a few oddball bits for a cross-country hardtail: a set of 685mm-wide Truvativ carbon riser bars and a Fi'zi:k Arione triathlon saddle. "This bike was initially set up with 640mm bars but those just felt dumb so we switched them out with the wider Noirs," he said. "As for the saddle, I tend to ride way up on the nose and the Arione is made for that."

Being the reigning 'All-Mountain World Champion', it’s not surprising that Decker runs relatively wide bars even on his cross-country bike. But a triathlete’s saddle? Hopefully he won’t start racing in sleeveless tri-tops and brief-style swimsuits.

Complete bike specifications

  • Frame: Giant XtC Composite 29er prototype, size L
  • Fork: RockShox Reba XX 29in, 100mm-travel, tapered steerer, 15mm through-axle dropouts
  • Headset: Chris King InSet
  • Stem: Truvativ Stylo World Cup, 110mm x +5°
  • Handlebar: Truvativ Noir carbon riser, 685mm
  • Grips: ODI Ruffians
  • Front brake: Avid XX World Cup, 160mm disc
  • Rear brake: Avid XX World Cup, 160mm disc
  • Brake levers: Avid XX World Cup
  • Front derailleur: SRAM XX
  • Rear derailleur: SRAM XX
  • Shift levers: SRAM XX
  • Cassette: SRAM XX, 11-36T
  • Chain: SRAM PC-1091
  • Crankset: SRAM XX, 175mm, 39/26T
  • Bottom bracket: SRAM XX press-fit
  • Pedals: CrankBrothers Candy 2
  • Wheelset: DT Swiss XRC 950 T (racing only)
  • Rims: DT Swiss X470, 32-hole, 3-cross, set up tubeless (training)
  • Front hub: DT Swiss 240s (training)
  • Rear hub: DT Swiss 240s (training)
  • Spokes: DT Swiss Competition, 14/15g
  • Front tire: Schwalbe Racing Ralph, 29x2.25in
  • Rear tire: Schwalbe Rocket Ron, 29x2.25in
  • Saddle: Fi'zi:k Arione Tri 2 Wing Flex
  • Seatpost: Truvativ Noir
  • Bottle cages: King Cage Titanium

Critical measurements

  • Rider's height: 1.83m (6ft)
  • Rider's weight: 72.6kg (160lb)
  • Saddle height, from BB (c-t): 807mm
  • Saddle setback: 90mm
  • Seat tube length, c-t: 495mm
  • Seat tube length, c-c: 440mm
  • Tip of saddle nose to C of bars (next to stem): 575mm
  • Saddle-to-bar drop (vertical): 20mm
  • Head tube length: 110mm
  • Top tube length: 615mm (horizontal)
  • Total bicycle weight: 10.04kg (22.13lb)

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