Soloist (Soloist Team and SL)
Taken from the Cervelo Website:
The 2004 Soloist Team features our new NarrowHead headtube. This headtube is almost as narrow as our original headtube, ensuring a small frontal area for aerodynamic reasons. At the same time, there is enough room inside the NarrowHead to fit a 1 1/8" steerer. So it offers the best of both worlds, narrowness for aerodynamics and a 1 1/8" steerer to increase the torsional stiffness (already a hallmark feature of the Soloist) even more.
The Soloist was designed for three types of riders:
And although the bike has a pure road geometry, the seatpost design allows you to flip the head forwards and achieve a more forward position, ideal for time trials. That means that you need only one bike for anything from criteriums to time trials, or from slow training rides to fast triathlons.
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.
Finally, the drag is minimized through a low frontal area; the tubes should be as narrow as possible when viewed form the front. Heavily oversized tubes negatively effect both the thickness-to-chord ratio and the frontal area of a tube, resulting in a drag of 4 to 6 times the drag of a Cervélo aerotube.
In our philosophy the range of frame sizes should be spread over the range of cockpit lengths that are needed. As people's torsos get shorter, so should the cockpit length. The cockpit length depends on the saddle set-back (how far is the tip of the saddle behind the bb), the hor. dim. (the horizontal distance between bb and headtube measured along the toptube) and the stem length. The stem is obviously separate from the frame, as is the saddle setback (a slack seattube angle with a zero offset post can have the same setback as a steeper seattube with a large setback post). So the frame dimension that really influences the cockpit length is the hor. dim. This dimension is affected by the toptube length and the seattube angle (since the toptube starts at the seattube, a steeper seattube moves the whole toptube forward and hence a larger portion of the toptube is in front of the bb, increasing the hor. dim.So what we do is we keep the seattube angle constant, and shorten the toptube consistently (not equally given the distribution of people riding the bike, but consistently) as we shrink the sizes. You could achieve the same decrease of cockpit length by shortening the toptube, steepening the seattube and then shortening the toptube an extra bit to compensate for that, but that's just a different way to achieve the same thing.
Unfortunately many bike companies do not understand this concept, so they shorten the toptube, then steepen the seattube, without being aware that this moves the toptube forward and hence increases the cockpit length again.
To give you an example, here are some numbers from the geometry of a well-known bike manufacturer::
So even though it looks like the changes between the sizes are consistent if you look only at the toptube lengths, the change is virtually non-existent between the smaller sizes. And the reverse effect occurs at the bigger sizes (size 59-61-63).
Aside from the problem with cockpit length, there is another reason not to slacken the seattube angle. Bigger size frames already put the saddle further behind the bb if the seattube angle is constant (simply because the seattube points rearwards and hence the higher you go along that line the further back the seat goes). Slackening the seattube angle adds another setback onto that already increased setback, thereby decreasing the hip angle of the rider to a point where power delivery is no longer optimal, or forcing the rider to raise his bars to keep the hip angle open, which would have negative aerodynamic implications with no advantage to show for it (compared to the same hip angle on a bike without the double increase in seat setback).
Showing up at Interbike in 2001 and first called the Solo:
The 2004 Soloist Team features our new NarrowHead headtube. This headtube is almost as narrow as our original headtube, ensuring a small frontal area for aerodynamic reasons. At the same time, there is enough room inside the NarrowHead to fit a 1 1/8" steerer. So it offers the best of both worlds, narrowness for aerodynamics and a 1 1/8" steerer to increase the torsional stiffness (already a hallmark feature of the Soloist) even more.
The Soloist was designed for three types of riders:
- Racers who want top aerodynamics for breakaways
- Roadies who want one bike for crits, road races and time trials
- Riders who do a few multisport events per year but want a road geometry bike for their other rides
And although the bike has a pure road geometry, the seatpost design allows you to flip the head forwards and achieve a more forward position, ideal for time trials. That means that you need only one bike for anything from criteriums to time trials, or from slow training rides to fast triathlons.
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.
Finally, the drag is minimized through a low frontal area; the tubes should be as narrow as possible when viewed form the front. Heavily oversized tubes negatively effect both the thickness-to-chord ratio and the frontal area of a tube, resulting in a drag of 4 to 6 times the drag of a Cervélo aerotube.
In our philosophy the range of frame sizes should be spread over the range of cockpit lengths that are needed. As people's torsos get shorter, so should the cockpit length. The cockpit length depends on the saddle set-back (how far is the tip of the saddle behind the bb), the hor. dim. (the horizontal distance between bb and headtube measured along the toptube) and the stem length. The stem is obviously separate from the frame, as is the saddle setback (a slack seattube angle with a zero offset post can have the same setback as a steeper seattube with a large setback post). So the frame dimension that really influences the cockpit length is the hor. dim. This dimension is affected by the toptube length and the seattube angle (since the toptube starts at the seattube, a steeper seattube moves the whole toptube forward and hence a larger portion of the toptube is in front of the bb, increasing the hor. dim.So what we do is we keep the seattube angle constant, and shorten the toptube consistently (not equally given the distribution of people riding the bike, but consistently) as we shrink the sizes. You could achieve the same decrease of cockpit length by shortening the toptube, steepening the seattube and then shortening the toptube an extra bit to compensate for that, but that's just a different way to achieve the same thing.
Unfortunately many bike companies do not understand this concept, so they shorten the toptube, then steepen the seattube, without being aware that this moves the toptube forward and hence increases the cockpit length again.
To give you an example, here are some numbers from the geometry of a well-known bike manufacturer::
So even though it looks like the changes between the sizes are consistent if you look only at the toptube lengths, the change is virtually non-existent between the smaller sizes. And the reverse effect occurs at the bigger sizes (size 59-61-63).
Aside from the problem with cockpit length, there is another reason not to slacken the seattube angle. Bigger size frames already put the saddle further behind the bb if the seattube angle is constant (simply because the seattube points rearwards and hence the higher you go along that line the further back the seat goes). Slackening the seattube angle adds another setback onto that already increased setback, thereby decreasing the hip angle of the rider to a point where power delivery is no longer optimal, or forcing the rider to raise his bars to keep the hip angle open, which would have negative aerodynamic implications with no advantage to show for it (compared to the same hip angle on a bike without the double increase in seat setback).
Showing up at Interbike in 2001 and first called the Solo:
Around 2007, the SL had already been added to the P3 and the P2k, and it was now available on the Soloist, see below: