So, what does this all mean for frame design?

Over the past decades, frames have been designed with shorter and shorter headtubes to please the pros seeking an advantage through a lower handlebar position. Those same geometries are then offered to the masses. As you’ve seen in part 1 and part 2, the only problem with this approach is that it’s wrong. It doesn’t work for the pros, let alone for the masses.

So we need to get these headtubes longer again, and thankfully there is a way to do this without creating a problem for those riders who like their low position (out of habit or because they have the flexibility to take advantage of such a low position).

You see this in the new Cervelo geometry for example. The R3, R5, R5ca and S5 are obviously race-ready, as they are used successfully by the men and women of Garmin-Cervelo. Yet the headtubes are taller than they used to be. Here’s how it works:

The new geometry from the Cervelo R3 and S5 series has a taller headtube so that people can put their handlebars on the correct height without needing too many spacers. At the same time the bars can still be placed low enough to fit any pro rider we have ever supported. The advantage of a longer headtube is that it increases the torsional stiffness of the frame, which in turn improves handling.

On aero frames, it also improves the aerodynamics because despite the headtube being wider than the bunch of spacers sitting atop of it if it were shorter, the shape of the headtube is much, much better and more than compensates for the increased frontal area.

So how do riders still attain the low position with the taller headtube? If you mount a -17 degree stem (that’s a flat stem, so a stem that sits on the bike horizontally) on the new geometry, the handlebars sit just as low as they would with a -6 degree stem (the standard) on the old geometry. 3T, FSA and several other manufacturers now have such -17 degree stems available.

Of course, that said no pro should ever ride the R3 except for Paris-roubaix (which it was designed for originally). The aero frames are ALWAYS the fastest solution, even in mountainous terrain, so every pro taking their profession seriously and wanting to get to the finish the fastest should ride them at all times (except Roubaix).

Yesterday we looked at how the body will find its ideal angles almost “despite” your efforts to put it in a different position. Therefore moving the handlebars lower will result in a more vertical arm position (as the shoulders remain in the same place). More vertical arms have two disadvantages:

1. Aerodynamics. More vertical arms means more frontal area and a worse shape for the arm cross sections (same width, less depth in the direction of the airflow).
2. Handling. With the arms more vertical and the elbow more stretched, handling is less precise. The more your elbows are in an angle, the more you push and pull on the bars which is good. Stretching your elbows means you’re “flailing” your arms more which gives less precision, rather than pushing on one side and pulling on the other. In descents, etc, this doesn’t really come into play as people will lower their back for the corners and pedaling action is not at peak performance then anyway, so this issue plays mostly when riding on the rivet in groups, especially in high effort, high stress situations like the classics on narrow roads. See also the advice from Henk Lubberding.

Of course, riders intuitively know all of this, or at least their bodies do. Which is why in the past 30 years as the trend progressed to move handlebars down, the amount of time spent in the drops has decreased and most time is now spent on the hoods. Which in turn explains why the riders of today sit just as low as those 30 years ago, despite having dropped their bars by 4″/10cm.

The information below we also share with our pro riders, to combat the misconception that lower handlebars are “better”. The basics:

1. The riders’ bodies have “built in” angles at which they can perform the best. So when a rider is at maximum effort, the body will put the body in the position most suited for that effort. In particular this pertains to the hip angle as it is the angle between legs and torso that determines mostly how the power is generated. Note: I am not talking here about increasing power by changing body angles, the power a rider can deliver is pretty much determined by his ability to transport oxygen and flush out lactic acid, but to generate that power (whatever level that is), the body will want to put itself into its optimal position, i.e. its optimal hip angle in order to best use the muscles best suited for the effort.
2. This means that with the bottom bracket and saddle fixed, when the body assumes its optimal hip angle, the back position is also determined. There simply is a position for the back at which the body is best capable of giving maximum performance, because it is the back position at which its angle with the legs are such that the optimal hip angle is achieved.
3. Hence, changing the handlebar height does not really change the back position, at least not during serious exertion. Therefore, with the back position more or less fixed, a change in handlebar position means a change in arm stretch/reach/angles. With the back more or less fixed, meaning the shoulders more or less fixed, the arms will assume whatever position it takes to connect the shoulders to the hands holding the handlebars (basically the elbows take up the slack).

The idea that you will sit lower if you just lower your bars is not true in most cases, other than the extreme (basically if you can only reach your bars with stretched arms, which is a bad idea based on the Lubberding point, then lowering those barrs would pull down your entire body into an unnatural position. But if that is a position you can sustain, then you can also keep your back in that position when you raise your bars from there and bend your elbows.

Next we’ll look at what this means for performance. Any comments or questions, please leave them in the comments section below or let me know via twitter @gerardvroomen.