Pro bike: Tom Zirbel's Jamis Xenith SL

American time trial specialist makes his return to the pro ranks

US cyclist Tom Zirbel (Jamis Sutter Home) is making his return to the professional ranks at this year's Tour of California after serving an 18-month doping suspension for DHEA. While some have invariably lambasted the comeback attempt, it seems that the majority have welcomed the affable Colorado resident with open arms. 

Either way, one thing hasn't changed: the man is a tall drink of water, standing at a towering 1.96m (6ft' 5in). Obviously, the numbers reflect that fact, too. Zirbel is racing this year on a 61cm Jamis Xenith SL frameset with a 590mm effective top tube that still has to be paired with a 130mm-long stem. His saddle height is 862mm (measured from the bottom bracket spindle center along the seat tube axis), setback is a generous 96mm, and bar drop is a tremendous 139mm. Compare those figures to your own bike if they don't sound big enough on paper.

Zirbel isn't just tall, though; he's also very powerful, packing 88kg (194lb) of muscle according to his profile on the team website. Helping to harness that horsepower is Jamis's size-specific carbon tube diameters and shapes with supposed "100 percent super-high-modulus M40 carbon fiber" content, a tapered 1-1/8 to 1-1/2in front end, and a large-diameter BB30-compatible bottom bracket shell.

Jamis xenith sl frames use bb30-compatible bottom bracket shells but as the team are sponsored by shimano - who still don't offer a proper bb30 crankset - they have to add threaded shell adapters: jamis xenith sl frames use bb30-compatible bottom bracket shells but as the team are sponsored by shimano - who still don't offer a proper bb30 crankset - they have to add threaded shell adapters

Jamis Xenith SL frames use BB30-compatible bottom bracket shells but as the team are sponsored by Shimano – who still don't offer a proper BB30 crankset they have to add threaded shell adapters

As has been the trend for the past few years, the Xenith SL does without any wild shaping, relying instead on mostly roundish cross-sections and smooth transitions that apparently help the chassis behave more cohesively and yield better numbers in the test lab. According to Jamis, tube shapes and diameters are also altered across the size range to help maintain consistent ride characteristics.

Zirbel's build kit is decidedly straightforward, consisting of a complete Shimano Dura-Ace mechanical group (with lengthy 177.5mm crankarms, of course), 35mm-deep Shimano carbon tubular wheels wrapped with Vittoria rubber, Speedplay Zero pedals with stainless steel spindles, and a pair of generic alloy bottle cages. 

Not surprisingly, Zirbel has opted for an all-aluminum cockpit from team sponsors Ritchey, including a forged WCS 4-Axis stem, classic-bend bar, and stout seatpost with the company's handy one-bolt head. Finishing things off are a Zoncolan Team Issue saddle and grippy bar tape from Selle San Marco. What is surprising, though, is the bike's total weight. Despite the size, Zirbel's complete rig weighs just 7.14kg (15.74lb) as pictured.

Tom zirbel (jamis sutter home) uses classic-bend bars but they're tilted unusually skyward: tom zirbel (jamis sutter home) uses classic-bend bars but they're tilted unusually skyward

Tom Zirbel (Jamis Sutter Home) uses an all-aluminum cockpit, including a classic-bend bar that's tilted unusually skyward

Complete bike specifications

  • Frame: Jamis Xenith SL, 61cm
  • Fork: Jamis Xenith SL
  • Headset: Ritchey WCS Carbon Drop-In, tapered 1-1/8 to 1-1/2in
  • Stem: Ritchey WCS 4-Axis, 13cm x -6°
  • Handlebar: Ritchey WCS Classic, 44cm (c-c)
  • Tape: Selle San Marco
  • Front brake: Shimano Dura-Ace BR-7900 w/ carbon-specific pads
  • Rear brake: Shimano Dura-Ace BR-7900 w/ carbon-specific pads
  • Brake levers: Shimano Dura-Ace STI Dual Control ST-7900
  • Front derailleur: Shimano Dura-Ace FD-7900-F w/ clamp-on adapter
  • Rear derailleur: Shimano Dura-Ace RD-7900-SS
  • Shift levers: Shimano Dura-Ace STI Dual Control ST-7900
  • Cassette: Shimano Dura-Ace CS-7900, 11-25T
  • Chain: Shimano Dura-Ace CN-7900
  • Crankset: Shimano Dura-Ace FC-7900, 177.5mm, 53/39T
  • Bottom bracket: Shimano Dura-Ace SM-FC7900 w/ BB30 adapter
  • Pedals: Speedplay Zero Stainless
  • Wheelset: Shimano Dura-Ace WH-7900-C35-TU
  • Front tire: Vittoria Corsa Evo CX tubular, 21mm
  • Rear tire: Vittoria Corsa Evo CX tubular, 21mm
  • Saddle: Selle San Marco Zoncolan Racing Team
  • Seatpost: Ritchey WCS 1-Bolt
  • Bottle cages: Aluminum (x2)

Critical measurements

  • Rider's height: 1.96m (6ft 5in)
  • Rider's weight: 88kg (194lb)
  • Saddle height, from BB (c-t): 862mm
  • Saddle setback: 96mm
  • Seat tube length, c-t: 570mm
  • Seat tube length, c-c: 520mm
  • Tip of saddle nose to C of bars (next to stem): 631mm
  • Saddle-to-bar drop (vertical): 139mm
  • Head tube length: 200mm
  • Top tube length: 590mm (horizontal)
  • Total bicycle weight: 7.14kg (15.74lb)

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