Why You Should Up-Size Your Track Bike 

Over the past few weeks since my Pre-Tokyo2020 Q&A on Instagram, I have had a flurry of questions asking why track riders should ride (at least) one size larger track bike than their road bike. 

Before I get into it, I’d like to note that I am not a bike fitter and nor am I an expert in biomechanics. These are my thoughts and experiences towards why current track cycling bike fits are as they are. This blog post is intended as a discussion - so if there's anything you don't agree with, or feel like needs more attention, please feel free to comment below with your thoughts.

Most of the track cyclists you see at your local velodrome are on bikes too small for them. In the past a track cyclist would ride the same size bike as they would on the road to replicate the bike fit for both disciplines. Back in the day with steel framed bikes some riders would even size down to reduce how much the frame would flex. We don't have to worry about frame stiffness anymore due to composite technology.

With a greater understanding of aerodynamics and biomechanics specific to cycling today, the ergonomics or bike fit of track cyclists and in particular track sprinters has evolved in conjunction with some minor changes to the UCI’s bicycle design rules.

A cyclist's aerodynamic drag accounts for upwards of 60% of the resistance upon the bicycle system. The majority of this is pressure drag which is the low pressure air holding the rider back.

https://www.sciencelearn.org.nz/resources/1346-causes-of-aerodynamic-drag

One of the simplest and most effective methods to reduce drag upon the rider is to reduce their frontal area. Reducing the frontal area limits how much air is displaced as the rider moves through it. This can reduce the volume of low pressure air behind the rider - making a more aerodynamically efficient system. Reducing frontal area involves getting long and low and narrow- which is achieved with some progressive changes to the bike fit and equipment.

Track cycling races are relatively short distances in comparison to road cycling, comfort and prolonged rider positions isn't a major issue, and most riders can justify sacrificing some comfort for a more aggressive and aerodynamic position. 

Reach

The most radical change towards a more aerodynamic bike fit is to increase the rider's reach. 

The total reach on a bike is the measurement from the vertical line of the Bottom Bracket spindle to the leading edge of the handlebar. This isn't to be confused with the frameset reach which is the measurement from the vertical line of the bottom bracket to the top of the headset.

https://www.ridemedia.com.au/product/australia-unveils-latest-argon18-track-bike-the-electron-pro/

The optimum total reach for each rider will vary. Before making any drastic changes to your setup, I would recommend visiting a professional ‘up with the times’ track specific bike fitter.. A quality bike fit is important if you are taking your riding seriously, as getting aero can compromise your power output or ability to sustain a high power output required over a race. With this in mind, take all of the following information and thoughts towards track bike bike fitting with a grain of salt, because what I might suggest for the purpose of this discussion may not be suitable for everyone.

A long reach achieves a couple of things:

1. Longer / lower posture

The longer your reach, the more outstretched your torso becomes. This can help with reducing your frontal area and CdA*

*CdA is an abbreviation for the coefficient of aerodynamic drag. It's a dimensionless number with no units. CdA is the result of a body's drag size, shape and surface texture.

2.More room for body movement

A longer reach provides more room for efficient body movement. I will talk more about this soon.

Saddle position

What the total bike reach metric (described above) doesn't include is the saddle position. The position of the saddle is a key contributor to the effective reach on the bicycle. In most cases, riders will position their saddle as far forward as the rules allow - this is in most cases 5cm behind the vertical line of the bottom bracket spindle. 

UCI Equipment Regulations ARTICLE 1.3.013 

https://www.ridemedia.com.au/product/australia-unveils-latest-argon18-track-bike-the-electron-pro/

Keeping your saddle as far forward as possible allows the rider's hips to rotate forwards to keep a low and flat back without forming an arch. While not always the best position for every rider in terms of biometrics and optimum power output, a forward saddle position keeps a more open hip angle at the top of the rider's pedal stroke.

Pushing your saddle forward does come with its issues. Remember that with a saddle pushed as far forward as it can legally go - you are effectively reducing your reach to the bars.

Frame Size/Design

The frameset is at the core of all the geometric requirements for an optimum aero fit. Yes you can swap out stems and bars to get a longer reach, but without a large enough frameset, you will forever be chasing your tail with compromises to your riding performance and control.

For the purpose of this discussion, when I refer to a frame size being XXcm this is referring to the length of the top tube.

Let's start with a short exercise. When you’re next riding your track bike, get down into an aero position, grip the bars at the front of the drop (where your hands would be positioned during a seated sprint), bend your elbows so that your forearms are parallel with the ground and begin to pedal. Take note of the relationship between your knees and elbows. Are your knees ever able to touch or move in front of your elbows? If they do, you're probably going to want to look for a larger frame. 

If you are a taller rider (over 6 foot), you may have noticed it's very difficult to get a hold of a XL track bike in the second hand market. This is because they are in hot demand with riders sizing up and adopting the new aero bike fit trend. Shorter athletes are in luck as there are plenty of medium and large frame options out there for you to choose from!

For a quick comparison guide, here is a quick spreadsheet of some Olympic medal winning riders from around the world and what size frame they were using for the Tokyo2020 Olympics. It's important to note that these riders have been meticulously set up on these bikes - and just because you may be a similar size to one of these riders, it may not mean that the size bike they rode will also be suitable for you. 

https://www.uci.org/docs/default-source/equipment/clarificationguideoftheucitechnicalregulation-2018-05-02-eng_english.pdf

Both the Large and Extra Large Kinsei framesets are pushed right out to the front wheelbase limit. The only difference is the height of the top tube - making the headtube and seat tube longer. This may seem kind of strange that Koga would have two very similar geometries of the same frameset manufactured, until you consider it's bar integration aerodynamic benefits (more about this below).

Bars and Stem

The next area to look at for optimisation is the handlebar and stem combo (commonly referred to as the cockpit). In my opinion, the cockpit is the most important part of the track bike for aero gains (not including the rider) as this area of the bike is the first to hit the clean air from in front of the rider.

I see the handlebars and stem of a bike as two components of a modular system. Each part can be swapped out to adjust your position, and optimise your bike fit for the best balance between aerodynamics, power output and control.

The rules for your handlebar position differs between endurance and sprint events on the track. For endurance, the UCI rules limit the maximum bar reach to be no more than 5cm past the vertical line of the front axle, where in sprint events, the limit is extended out to 10cm past the axle. These rules are intended as a safety measure to maintain control on the bike.

UCI Equipment Regulations ARTICLE 1.3.022

In no case shall the front of the handlebars exceed the tolerance of 5 cm in relation to a vertical line passing through the front wheel axle, which is the control zone of the bicycle. The more forward the handlebar is positioned, the less maneuverable the bicycle will be and the less it will be easy to react quickly to an obstacle or a wind gust. Moreover, this would result in moving the center of gravity of the rider on the bicycle, which would increase even more the risks of loss of control.  

Endurance Bars

On a road bike, a cyclist will be riding in the hood position the majority of the time. Hoods on a road bike hang out in front of the handlebars, further increasing their reach from the drops. The hoods also allow you to drop your forearms into a horizontal position which reduces a bit of the rider's frontal area. To achieve a similar position of the track bike - while keeping within the handlebar 5cm limit, riders opt for a longer reach frameset to compensate for the difference in reach. The Velobike Bunch Bars are designed with the hoods integrated into the bar to replicate road bike hood riding position while keeping within the UCI reach rules and equipment design regulations.

Handlebar width is another important consideration to have when it comes to aero. More riders are opting for narrower bars than they may have previously been riding. Narrow bars can reduce the rider's frontal area - tucking the arms in line with the torso. Narrow bars also make it easier to weave through the peloton during bunch events. Narrow handlebars do come with a minor compromise to handling. With narrow bars it can be a tad more difficult to make controlled steering adjustments during the ride, but this is something that you can quickly get used to. Once you go narrow, everything else feels like you are riding a tractor - especially going back to the road bike.

The Bunch bars feature a 330mm wide drop, narrowing  to 264mm at the tip of the hoods. The narrower hood section means the rider can tuck their forearms in and ride off the front of the peloton in clean air similar to a pursuit bike with aerobars.

Sprint Bars/Stems

Sprinters are among the fastest bike riders out there. The top level sprinters are reaching top speeds over 80kph (50mph). At these speeds, a low CdA is very important. 

When a sprinter does a 100% effort, they will reach a point where they stop accelerating and can’t go any faster. This is the point of equilibrium between input power and the drag / friction forces against you. 

There are two ways to go faster:

1. Increase your power output
2. Reduce your resistance (aerodynamic drag being the primary contributor)

The relationship between the power required to ride at these higher speeds is exponential (increases at a non linear rate) due to the drag factor, which means that the faster you are riding, the greater the difference in power you need to put out to continue to accelerate.. Therefore being strong is one thing, but getting a fraction more aero can make a considerable difference in speed. This could be what makes the difference between winning a medal and not.

The diagram below form Sheldon Brown illustrates the exponential increase in power required to overcome the increase in resistance with an increasing velocity. Note that the graph is just to illustrate the relationship between these values. The figures used in the the graph may not be accurate or representative to track cycling.

How does all of this relate to bars and stems for sprint bike setups?

As mentioned above, the handlebar reach rules for sprint events are longer than for endurance bike setups. Track sprinters take great advantage of these rules to optimise the aero even more than you see on bunch racing bikes. Professional level sprinters are on the longest bikes possible with really long stems. 

A bike with a long stem can feel a bit wollowly. The arc that your hands have to travel to make any sudden turns is longer, and thus slightly less responsive and agile. On the other hand, long stems are quite stable to ride, and allow riders to use narrower handlebars without compromising on control. At the Tokyo2020 Olympics, sprint cyclists were running bars as narrow as 280mm wide in the drops.

Slammed stems with the drops underneath the height of the front wheel is a thing of the past. You may have noticed a lot of riders are increasing the height of their bars also. Even with many XL size frames, many riders have steep upward angled stems or have a bunch of spaces on their steerer tube. The higher bar height helps with keeping your forearms horizontal with the ground while still maintaining a flat back and low body position.

A long front end with high bars is a desirable setup for standing starts too. The extra length means that the rider can launch themselves further forward, getting over the bars a little bit more and extending the period that the rider can put power through the pedals over the deadspot zone in the crank revolution.

Great Brittan Team Sprint, Tokyo2020, https://morecadence.jp/track/87636/2

For the Tokyo2020 Olympics we developed the Longboi Sprint Stems for the New Zealand Sprint team. 

The stems feature a reverse bolt faceplate mounting system to remove the clutter from the leading edge of the stem, while integrating the tapered bolt heads into the trailing edge of the airfoil profile of the stem. 

The Longboi stems are machined from the highest strength to weight ratio aluminium available, meaning that even with custom stems over 170mm in length they offered superior stiffness. Sam Dakin from the New Zealand Olympic sprint team mentioned that his Longboi was the stiffest stem he has ever used.

That's all from me in this blog post on modern track bike sizing and equipment. No doubt I will have more points to add to it over time. Let me know down below in the comments what you think I've missed.