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Pro bikes, February 21, 2008

David Zabriskie's Garmin-Slipstream p/b Chipotle Felt DA

Photo ©: James Huang

US national time trial champion's speed machine

A key feature of the DA is the Bayonet II fork
Photo ©: James Huang
(Click for larger image)
Lengthy trailing edges behind the fork tips
Photo ©: James Huang
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The unique hinged Bayonet stem
Photo ©: James Huang
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Cables are internally routed and enter the frame
Photo ©: James Huang
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The dropped down tube and modest wheel cutout
Photo ©: James Huang
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The rear wheel is shielded all the way from the bottom bracket
Photo ©: James Huang
(Click for larger image)

By James Huang

David Zabriskie hasn't earned his reputation as one of the best time trial riders in the world by being slow.

He has earned four US national time trial titles (2004, 2006-2008), a silver medal at the UCI world TT championships (2006), and time trial victories in all three grand tours, including the fastest Tour de France time trial ever recorded (stage 1, 2005) with an average speed of 54.545km/h (33.89mph) over 24.5km (15.2mi).

His position on a time trial bike stands in marked contrast to his famously quirky personality and to watch him gracefully hunkered down over a set of aero bars at speed is to watch the very epitome of what a time trialist should look like: long, low, fluid, graceful. In fact, his position is so perfect that former sponsor Cervélo actually had a plastic life-sized mockup of him built to aid in wind tunnel testing of its bikes.

Zabriskie has since moved on to the Garmin-Slipstream squad and on to a new bike, the Felt DA. Just like Zabriskie, the DA looks every part the dedicated time machine it is.

The DA naturally uses aero-profile cross sections for all tubes exposed to the wind, but Felt has also gone several steps further to reduce drag and smooth airflow. The most prominent feature is the Bayonet 2 fork, whose external steerer tube combines with the narrow 1" head tube to effectively create a much deeper aspect ratio than the UCI would allow with a single frame member.

According to Felt, the Bayonet 2 system - which also integrates a low-profile stem up top - accounts for a substantial 10 per cent drag reduction over a standard front end, while also being stiffer for better handling and braking.

In addition to the especially expansive rear wheel cutout, the down tube is also partially profiled and lowered to smooth airflow coming off the front wheel. Down below, Felt has moved the rear brake from the seat stays to atop the chain stays just behind the bottom bracket where the air is already turbulent.

Felt claims a four percent drag reduction as a result, and the dropped chain stay position also makes for a longer down tube for additional rear wheel shielding. Cables are routed internally to minimise drag and enter the frame at the top tube behind the stem.

Componentry includes speedy Zipp 800 deep-section front and 900 flat disc rear carbon tubular wheels, Shimano's latest Dura-Ace 7900 group and its fresh carbon fibre TT brake levers, a new TT-specific Ares saddle from fi'zi:k and integrated aero bars from new team sponsor 3T. Ceramic bearings from new official sponsor CeramicSpeed - Zabriskie had used them before but in an unofficial capacity - are fitted to the bottom bracket cups and Zipp supplies its own ceramic bearings for the hubs.

The team's switch in aero bars has required some fairly drastic changes up front as 3T currently offers its Brezza bar in a single, relatively flat drop. Zabriskie's adjustable Bayonet 2 stem is now angled sharply downward in order to get the relatively flat base bar low enough but other riders - including team leader Christian Vande Velde - have had to resort to an additional hinged section to get even lower. Felt says specially modified special team-only front ends are pending so we can likely expect some changes come the Giro d'Italia.

In spite of the DA's massive amounts of surface area, it's actually quite light as well. Claimed weight for the frame and fork is just 1500g and total weight for Zabriskie's complete bike is just 7.6kg (16.8lb) - not quite down to the UCI limit but still exceptionally light for a dedicated time trial rig.

The Tour of California is winding down but Zabriskie and several others are still within striking range of the leader board. After taking second in the Solvang time trial, Zabriskie currently stands in second place on GC, just 36 seconds behind overall leader Levi Leipheimer.


For a thumbnail gallery of these images, click here

Images by James Huang/Cyclingnews.com

Full specification

Frame: Felt DA UHC-Nano, 54cm
Fork: Felt Bayonet II UHC-Nano

Critical measurements
Rider height: 1.82m (6'0")
Rider weight:
70kg (154lb)
Seat tube length, c-t:
Saddle height, from BB (c-t): 785mm
Tip of saddle nose to C of bars (next to stem): 625mm
C of front wheel to top of bars (next to stem): 476mm
Top tube length: 545mm

Front brake: Shimano Dura-Ace BR-7900 w/ SwissStop Yellow King pads
Rear brake: Shimano Dura-Ace BR-7900 w/ SwissStop Yellow King pads
Brake levers: Shimano Dura-Ace TT BL-TT79
Front derailleur: Shimano Dura-Ace FD-7900-F
Rear derailleur: Shimano Dura-Ace RD-7900-SS
Shift levers: Shimano Dura-Ace bar-con SL-BS79
Cassette: Shimano Dura-Ace CS-7900, 11-23T
Chain: Shimano Dura-Ace CN-7900
Crankset: Shimano Dura-Ace FC-7900, 175mm, 53/39T
Bottom bracket: Shimano Dura-Ace SM-FC7900 w/ CeramicSpeed hybrid ceramic bearings

Front wheel: Zipp 808 tubular w/ ceramic bearings
Rear wheel: Zipp 900 tubular
Front tyre: Vittoria Corsa Evo-CX tubular, 23mm
Rear tyre: Vittoria Corsa Evo-CX tubular, 23mm

Bars: 3T Brezza LTD, 40cm (c-c)
Stem: Felt Bayonet II, 120mm x -18º
Headset: Felt Bayonet 1" integrated
Tape/grip: fi'zi:k Dual:Tape

Pedals: Shimano Dura-Ace SPD-SL PD-7810
Seat post: Felt 3.1
Saddle: fi'zi:k Ares
Bottle cages: Arundel Chrono
Computer: Garmin Edge 705

Total bike weight: 7.6kg (16.8lb)