Cervelo Dual
As Dan Empfield, founder of Quintana Roo and editor of slowtwitch.com, put it: "Cervélo has upped the ante with the Dual in a very popular price point, and the other tri bike makers will have to respond to it (no one at the [Interbike trade] show did)". With a dual aero frame, Ultegra components, race-ready wheelset & aerobar and a price for the complete bike that rivals some frame-only prices of the competition, the Dual is the perfect bike for those who want pro-level performance at an affordable price. No wonder it is American Tri's Editor's Pick in the under $2000 category.
To optimize aerodynamics, the tubes need to have a very specific shape, a profile determined by the National Advisory Committee on Aeronautics (NACA). This shape can only be obtained by extruding the tubes, as forming round tubes imposes too many shape limitations. As an example, a round tube has about 5 times the drag of a NACA-profile, while a crushed tube is about 3 times as bad. A very important part of the shape is its thickness-to-chord ratio. If this ratio is high (meaning the tube is relatively wide compared to its depth), the air flow will detach, creating turbulence and high drag.
It is also important to note that the correct NACA profile is not round at the front but eliptical. Aerotubes with a round front and sharp trailing edge are becoming more and more popular (because it they are easy to make out of a round tube, and because they will easily take a round seatpost if used as a seattube). But unfortunately they offer hardly any aero benefit, as the bluntness of the round front already deflects the airflow before it reaches the trailing edge.
Which wheelsize is faster depends on how big you are and the position you ride in. It all comes down to putting the rider in a comfortable and aerodynamic position, and designing the bike around that.
Rider Position: If the rider rides in an aero position, the handlebars and aerobars will usually be in a relatively low position, lower than on a road bike. In a small frame size, this low position of the bars can conflict with the size of a 700c front wheel, as the big wheel and the low bars wouldn't leave enough room for a headtube. Hence for small sizes we recommend 650c wheels. For larger sizes, a good position can be obtained over either a 650c or 700c front wheel, provided that in both cases the headtube is kept short enough (shorter than on a road bike of the same size).
Bike Aerodynamics: Since both wheel sizes will work on bigger frames, the optimal frame will be the one with the lowest drag. While a 650c wheel has slightly less drag and uses a slightly more aero fork (shorter fork legs), a 650c frame will have a 2" longer headtube, assuming an identical aerobar position. Our windtunnel testing shows that due to that shorter headtube, a 700c bike will actually be slightly more aero than a 650c bike. Therefore, for the larger sizes we recommend 700c wheels, but for mid sizes the customers' current equipment and other factors will also enter into the equation.
- Cervélo Smartwall 2 tubing with Full TrueAero frame and aero seatpost
- ICS (Internal CableStops), the best internal cable system available
- 650c/700c wheel size optimized per frame size
- Adjustable geometry with 74-79 degree seattube angle range
- UCI legal
- Aero seattube
- Aero seatpost
- Ultegra components
- Adjustable geometry
- Profile Carbon Stryke aerobars
- Integrated headset
To optimize aerodynamics, the tubes need to have a very specific shape, a profile determined by the National Advisory Committee on Aeronautics (NACA). This shape can only be obtained by extruding the tubes, as forming round tubes imposes too many shape limitations. As an example, a round tube has about 5 times the drag of a NACA-profile, while a crushed tube is about 3 times as bad. A very important part of the shape is its thickness-to-chord ratio. If this ratio is high (meaning the tube is relatively wide compared to its depth), the air flow will detach, creating turbulence and high drag.
It is also important to note that the correct NACA profile is not round at the front but eliptical. Aerotubes with a round front and sharp trailing edge are becoming more and more popular (because it they are easy to make out of a round tube, and because they will easily take a round seatpost if used as a seattube). But unfortunately they offer hardly any aero benefit, as the bluntness of the round front already deflects the airflow before it reaches the trailing edge.
Which wheelsize is faster depends on how big you are and the position you ride in. It all comes down to putting the rider in a comfortable and aerodynamic position, and designing the bike around that.
Rider Position: If the rider rides in an aero position, the handlebars and aerobars will usually be in a relatively low position, lower than on a road bike. In a small frame size, this low position of the bars can conflict with the size of a 700c front wheel, as the big wheel and the low bars wouldn't leave enough room for a headtube. Hence for small sizes we recommend 650c wheels. For larger sizes, a good position can be obtained over either a 650c or 700c front wheel, provided that in both cases the headtube is kept short enough (shorter than on a road bike of the same size).
Bike Aerodynamics: Since both wheel sizes will work on bigger frames, the optimal frame will be the one with the lowest drag. While a 650c wheel has slightly less drag and uses a slightly more aero fork (shorter fork legs), a 650c frame will have a 2" longer headtube, assuming an identical aerobar position. Our windtunnel testing shows that due to that shorter headtube, a 700c bike will actually be slightly more aero than a 650c bike. Therefore, for the larger sizes we recommend 700c wheels, but for mid sizes the customers' current equipment and other factors will also enter into the equation.