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Pro bike, July 25, 2008

Kim Kirchen's Team Columbia Giant TT Prototype

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Photo ©: Ben Atkins

Radical new shape for Team Columbia

By Ben Atkins

The slender top tube intersects
Photo ©: Ben Atkins
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Huge amounts of carbon around the bottom bracket
Photo ©: Ben Atkins
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The seat tube closely profiles the rear disc wheel
Photo ©: Ben Atkins
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The rear end of the prototype frame
Photo ©: Ben Atkins
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Straight aero seat stays
Photo ©: Ben Atkins
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Kirchen's down tube is deep but slender
Photo ©: Ben Atkins
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The huge head tube area
Photo ©: Ben Atkins
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Team Columbia's Kim Kirchen came to this year's Tour de France as a genuine podium contender after finishing seventh in last year's event and capturing a difficult mountain win (he was awarded victory in stage 15 from Foix to Loudenvielle-Le Louron after Alexandre Vinokourov was disqualified). The Luxembourger has made another good showing so far this year: he captured the maillot jaune after stage 6 and held it for the next four days but fell back to seventh overall after stage 10's difficult finish atop Hautacam.

Kirchen currently lies in eleventh place in the general classification but is almost certain to crack back into the top-ten after Saturday's 53km-long race against the clock with the help of a slippery new time trial bike from team sponsor Giant. According to the Taiwanese company, the radical-looking - and as yet unnamed - machine is "the fastest UCI-approved TT bike ever in the history of competitive cycling." A bold statement indeed, but one that Kirchen's superb second-place performance in stage 4's 29.5km time trial adds some weight to.

Giant collaborated with UK design consultancy firm Velo Science to create the new shape which utilizes a number of innovative aero features. Even so, much of the frame actually resembles Cervélo's P3 benchmark with its deep aero-section down tube and vertically oriented seat tube that closely shadows the rear wheel. Likewise, almost rectangular section chain stays hug the rear tyre before flaring out slightly to envelop the hub and contrastingly slender aero section seat stays perform a similar task further up.

It is the front end of the bike though that really catches the eye and sets this out from every other one out there. The bladed composite fork and the hugely aerofoiled head tube that it fits into are not in themselves particularly unusual but the stem and bar system attached and integrated into them certainly are.

The stem top fits snugly to the fork and its lines flow almost seamlessly into the top tube which has been raised significantly so that they are positioned inline with each other. Down below the stem, a huge wedge shape - much like the bow of a ship - extends down to the fork crown and completely hides the front of the head tube from view.

This wedge is Giant's take on cleaning up the lines on the front of the bike, a place where exposed gear and brake cables can apparently lay waste to a lot of wind tunnel development. Cables pass internally through the base bars and extensions then enter the bow-shaped wedge. They then pass through the fork and under the brake caliper - between it and the front tyre - before disappearing into the underside of the down tube. The cables are then passed internally before emerging once more close to the point where they are needed.

Kirchen's bar set up is also made in-house by Giant, and is part of the same project. These take the form of huge, flat, wing-shaped outer sections with round section outer grips. Surprisingly, Giant has not included integrated brake levers here - perhaps these will come later in the project - but instead Columbia is using minimalist bar end levers from Vision. PRO, who supplies Columbia with its regular handlebars and stems, also provides the extensions and elbow pads.

The result of all of this extensive shaping and wind tunnel testing is, at least according to Giant and Velo Science, "one of the lowest drag coefficients in the world".

As a rider on a Shimano sponsored team, Kirchen's groupset - besides the custom scissor-style brake calipers (made by Prime Aero in Taiwan) and Vision levers - is entirely Dura-Ace although all of the team's time trial bikes are built up with the established 7800 version. Kirchen's bike was also set up with a Zipp Sub9 rear disc and 404 front wheel (both with 22mm-wide Schwalbe Ultremo tubulars) when we caught up with it although we'll have to wait until Saturday to see what he ultimately decides to run that day. .

Finishing things off is a Selle Italia SLR saddle, which - as is usual these days - has had its nose chopped in order to keep within the UCI's regulations regarding its position in relation to the bottom bracket.

Kirchen's time - as well as positive feedback from Team Columbia's women's arm while racing at the Giro d'Italia Femminile - would suggest that Giant has successfully created a very fast bike. Saturday's deciding time trial will provide one more real-world test in this year's Tour de France but come next month, Kirchen will hope that the frame will carry him to Olympic success, too.

Photography

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Images by Ben Atkins/Cyclingnews.com

Full specification

Frame: Giant TT carbon prototype
Size: N/A
Fork: Giant TT carbon prototype

Critical measurements
Rider's height: 1.73 (5' 8") ; Weight: 67kg (147lb)
Seat tube length, c-c: N/A
Seat tube length, c-t: N/A
Top tube length: N/A
Saddle height, from BB (c-t): 755mm
Saddle nose tip to C of bars: 600mm
C of front hub to top of bars: 470mm

Front brake: Custom
Rear brake: Custom
Levers: Vision aero levers
Front derailleur: Shimano Dura-Ace FD-7800
Rear derailleur: Shimano Dura-Ace RD-7800-SS
Gear levers: Shimano Dura-Ace bar-end SL-BS78
Cassette:
Shimano Dura-Ace CS-7800, 11-21T
Chain: Shimano Dura-Ace CN-7801
Crankset: Shimano Dura-Ace FD-7800, 172.5mm, 53/39T
Bottom bracket:Shimano press-fit

 

Front wheel: Zipp 404 tubular
Rear wheel:
Zipp Sub9 tubular
Tyres: Schwalbe Ultremo 22mm tubular

Bars: Giant prototype with PRO extensions, 40cm (c-c)
Stem: Giant prototype
Headset: integrated
Tape/grip: none

Pedals: Shimano Dura-Ace SPD-SL PD-7810
Seat post: Giant carbon fibre aero prototype
Saddle: Selle Italia SLR with chopped nose
Bottle cages: N/A

Total bike weight: 8.150kg (17.97lb)