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Tech Report, with Lennard Zinn – The new Madone

  • By VeloNews.com
  • Published Jun. 5, 2007

By Lennard Zinn

The newest Madone from Trek

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“If I had asked people what they wanted, they would have said faster horses.”

Henry Ford

In a move surely destined to strike fear into the hearts of high-end seatpost manufacturers, Trek unveiled its new Madone road bike at a gathering of Trek dealers and cycling media on May 31.

Under the soaring white trusses and glass of the stunningly beautiful Milwaukee Art Museum, Lance Armstrong joined Trek president John Burke in introducing a bike that is could alter the direction of bicycle design in a number of ways.

To start, the new frame has no threads in a very unique 90mm bottom bracket shell. A standard shell is 68mm. The “All New Madone” also has no seatpost, instead using an integrated seat mast, but unlike seat masts from other manufacturers, Trek’s seat mast is closed on the top and is not to be cut to length. Instead, Trek has a clamp-on cap made of carbon fiber or aluminum (depending on model) that fits over the seat mast and offers a range of vertical, horizontal, and rotational adjustment. Finally, the fork is 1.5-inch diameter at the top of the fork crown and the standard 1.125-inch diameter where the stem clamps on.

A new approach to bottom bracket shell design

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The frame is revolutionary not only in these dimensions, but in the fact that the carbon fiber on both the frame and fork is precisely “net molded” to accept headset and bottom bracket bearings with not only no cups required, but also no machining required. With your hands, you simply pop in the bearings into the ends of the head tube and the bottom bracket shell. The only tool required is a hex key to tighten the headset top cap and to attach the left crankarm on (it takes integrated-spindle cranks from all major manufacturers).

Trek has invested an unprecedented amount of time and money into testing this frame and is confident that the frame will far outlast the bearings several times over. In fact, its tests showed that the steel of the bearing cartridges gets worn down and notched after enough time on the pedaling through water day and night at 85rpm, and the steel balls themselves crack. But the carbon fiber shows no sign of wear—a completely unexpected result.

Mechanics are bound to be pleased, as assembly is faster and quicker and requires no unusual tools. And though the bottom bracket shell is 22mm wider than standard, pedaling stance is unchanged; the bearings sit in exactly the same position as they would have with external-bearing thread-in cups. And the wider BB shell allows the use of a huge down tube diameter – 74mm – to offer great torsional and lateral stiffness with very low weight. The down tube is also asymmetrically flatter on the drive side at the bottom bracket shell to give clearance for the crank. The same applies to the chainstays, which meet the shell in a big 75mm-wide box-shaped yoke, and the drive-side chainstay is thinner and taller than the wider, triangular-section left chainstay.

As is the case with the bottom bracket, the “Precision Fit Sockets” in the huge lower end and standard-diameter upper end of the head tube also allows bearings to be fit by hand and will also wear longer than the bearings by far. And the fork is incredibly light and has neither any machining nor any 90-degree beds in the carbon, both of which would weaken it. The lower bearing fits on the angling-out skirt at the top of the large thinwalled fork crown.

All of these changes save nearly a pound of weight off the 2007 Madone, yet they add strength and torsional rigidity while providing more vertical compliance by virtue of the design of the slightly flexible seat mast and seat tube.

Bonding on the last of the five main molded parts forming a Madone frame

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The new Madone is revolutionary because it optimizes the characteristics of carbon fiber without being constrained by the dictates of specifications like bottom bracket threading, headset cups, and a seatpost clamping system. It also requires far fewer parts in the headset and bottom bracket. And there is no seatpost to require a precise, reamed fit or to allow water down into the seat tube and freeze into it, yet there is also no sacrifice of adjustability.

While many of us like the look and low weight of the integrated seat masts from other manufacturers, few of us like cutting our frame to size with a hacksaw. And features like integrated seat masts and press-in bottom bracket bearings exist from other manufacturers, but only at the high end, while Madones will be offered in Pro and Performance Fit (with a taller head tube) designs from Ultegra-equipped Madone 5.1s made of lower-modulus carbon and with simpler fabric layups to Madone 6.9s with the highest-quality fibers laid up in exacting and complex layups and equipped with only the trickest components.

“We didn’t want incremental improvement; we wanted to leapfrog the competition,” explained Burke.

My first impression is that Trek accomplished that.

Look for my full report on the new Madone and Trek’s new Fuel mountain bike in the upcoming print issue of VeloNews.


VeloNews technical writer Lennard Zinn is a frame builder (www.zinncycles.com),a former U.S. national team rider and author of numerous books on bikesand bike maintenance including the pair of successful maintenance guides”Zinnand the Art of Mountain Bike Maintenance” and “Zinnand the Art of Road Bike Maintenance” as well as “Zinn’sCycling Primer: Maintenance Tips and Skill Building for Cyclists.”

Zinn’s VeloNews.com column is devoted to addressing readers’ technicalquestions about bikes, their care and feeding and how we as riders canuse them as comfortably and efficiently as possible. Readers can send brieftechnical questions directly to Zinn (veloqna@comcast.net)Zinn’s column appears each Tuesday here on VeloNews.com.

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