Monday, 14 December 2015

Back to Basics - Road Race Sprinting Part 2: Technique

Sprinting Technique - Simple, you just go as fast as you can don't you?

Life is of course never that simple and in sprinting there is much more to technique, and that's before tactics are taken into account (that will be the content of my next "Back to Basics" post).

Go as fast as you can?

Surely how fast you can go varies with how far you want to go? Some people believe that sprinting must be the absolute fastest you can go, your ultimate peak speed.

Does that make sense? At the end of a road race the actual sprint effort might need to cover anything from as short as 150m to as long as 400m depending on the circumstances, wind, gradient, competition etc. If you think that "as fast as you can go" is the same for 150m as it is for 400m then you are going too slowly for the shorter distance. It is perfectly possible to "blow" in an effort as short as a sprint just by trying too hard too soon.

If your top speed can be maintained for more than a very few seconds then you ought to be abler to go a bit faster and there are likely to be some technical rather than purely power based issues that you can resolve and by doing so boost that top speed.

During that last few hundred metres of a race, which takes between 10 and 25 seconds to cover, the sprinter will make decisions. The business of exactly what line to take, which riders to follow, how hard to go, when to hit absolute maximum and when to hold a pace just below that are the realm of tactics and not for today's post. But how to actually ride at the highest possible speed for the distance you need to sprint, how to accelerate either as quickly as possible or quickly enough while retaining a little power - those are the aims of this post.


Many people see the professionals sprint at Tour de France finishes on massive gears like 53x11 and assume that is what you need to go very fast, fast enough to win sprints. In reality those professionals are often coming off a lead out where they are already travelling at almost 40mph (60kph) before they actually start sprinting. In most other circumstances the sprint in unlikely to start from a speed over 30mph and often more like 25mph (40kph).

It doesn't take much maths to realise that the same gear would not be appropriate. The biggest differences between the Tour de France sprint and the typical amateur sprint finish are:
  • The slower starting speed in the amateur sprint means greater acceleration to reach the top sprinting speed
  • The top speed reached is likely to be lower than the professional sprint
  • The amateur sprint is often (not always) shorter than the professional one
All of those mean that getting that really big gear spinning really fast is unlikely to happen.

This is getting towards the tactics that will be discussed in my next post but the important thing here is that to sprint very fast doesn't mean being in that massive gear unless you've had a really fast lead out to the sprint.

To emphasise that point most riders don't realise just how fast it is possible to sprint on a fairly small gear. It is perfectly possible to sprint at 35mph and faster on gears of around 42x15 or 52x18 (that will also get a mention in the soon to follow post covering training techniques).

Balance and power transfer

In order to go as fast as possible the sprinter can't afford to waste energy and there are plenty of ways to waste that energy; for example if you stand up to sprint and the back wheel skips just a little bit you've not only wasted energy but also wasted a little bit of momentum slowing your acceleration or losing a bit of speed and then having to use up even more energy to get it back.

Many equipment reviews will report on how effective or otherwise the rear triangle and geometry of a particular race bike is at tarring power through to the back wheel or the road. The "Back to Basics" point here is that any modern race bike will do better at transferring that power than most riders themselves will manage unless they develop really good technique.

With your weight too far forward on the bike traction can be lost and that skipping wheel will slow the sprint and cost energy. If the weight is spread too far back the ability to use more of the body to get that power to the road is compromised, in addition the ability to control the bike is also affected so speed and energy are likely to be thrown away in all directions.

Other issues with body position affect the aerodynamics of the bike and rider and the ability to deal with issues that might arise during the sprint (taking evasive action, keeping yourself from being pushed off line etc.) - and that's without considering the distance from the saddle to the pedals (I'm assuming that the racer keen to improve his or her finishing sprint will have already sorted that out - perhaps the makings of another Back to Basics topic?).

Rapid and relaxed pedalling

In order to ride a bike really fast it is essential to be able to pedal very quickly, simply going for bigger and bigger gears just won't work as the torque required will be too high to deal with wind resistance as speed. The power you transfer to the pedals is the combination of the torque exerted and the speed of the legs - revolutions per minute (rpm). Just as a car will strain if you try to accelerate in too high a gear so will a cyclist. To accelerate you need a gear which you can quickly accelerate to high rpm and then for the remainder of the sprint you need to maintain that high rpm (some people will change gear once up to speed but the momentary loss of power whilst changing is likely to remove any perceived advantage).

High rpm on the context of sprinting means being able to accelerate from around 100rpm to around 130rpm whilst still standing and to pedal at a limit of at least 150rpm - many sprinters can pedal faster than 180rpm - that's more than three downward pedal strokes for each leg in the space of a second. Fortunately the technique can be learned and developed further through effective training. It isn't really all that fast - consider that Chris Froome can pedal up very significant slopes at 120rpm.

We all know people who believe they can never pedal faster than about 100rpm; sadly those people will not sprint quickly until they let go of that belief and learn to spin much, much faster. physiologically there really is no reason why any able-bodies cyclist cannot learn to pedal well in excess of 100rpm.

Technically fast pedalling requires the cyclist to be relaxed, to have a good position on the bike and a certain degree of concentration. Any movement other than spinning the legs will be exaggerated as the legs spin faster and those movements are often the real cause of the limit a rider feels when pedalling fast.

Here's a little bit of the science:

In order to ride twice as fast at a constant speed in still conditions on a flat road the amount of power needed to move through the air will be four times as much. Other energy use doesn't increase exponentially this way but pretty soon as speed goes up the only really significant need for power is to overcome that air resistance. If a rider needs say 210Watts to ride at 20mph at least 200 of those will be to push through the air. To double the speed to 40mph would require four times the power to push through the air plus the 10Watts for the other factors (friction, waste etc.) so the total power needed would be 810Watts. Imaging then that the rider is not riding at a constant speed but is accelerating to that 40mph from around 20mph - the power required for that acceleration will depend on the weight of the rider and how fast they want to increase their speed but it is suddenly easy to see how a fast road sprinter will need a peak power of over 1500Watts - Mark Cavendish is reputed to generate around 1800Watts maximum and most sprinters are significantly bigger and need to generate over 2000Watts to have any chance of matching him.

Those figures are just there for demonstration purposes - this is Back to Basics and unless you've got really close to your potential in all other regards you really don't need to know your own numbers.

Power meters, blood and oxygen values and all the little "marginal gains" are the realm of the likes of Team Sky who have not only the equipment to capture the numbers but also the specialists with knowledge to undersatnd and use it. For most riders the application of the techniques here and the training and tactics in the following pages can make "substantial gains" without the investment of anything other than thought and training.

The jump

The jump is the moments where a rider accelerates to sprinting speed and all that balance and control is most important here as this is often the point where any possibility of success or failure is created.

In most cases the rider will accelerate by standing on the pedals, weight fairly centred on the bottom bracket and as each leg pushes at high torque the body and particularly the arm on that side will create a strong platform against which the leverage of the leg can be exerted.

Hands and arms - At this point the hand on the side doing the pushing must grip the bars strongly and the arm pull against the leg - it doesn't need white knuckle grip but a good solid grip that won't let go.  If the arm pulls strongly enough then the bike will rock to the left as the right leg pushes and then as the left leg pushes it will rock to the right. Very often novices and younger riders will exaggerate the rocking movement believing that it will make them faster - it won't; the rocking should only be generated as a result of the amount of power being put into each pedal and the reactive pull on the same side of the handlebars, anything else is wasteful.

If you've ever seen a rider accelerate with a slightly hollow back pushing hips rather than thighs downwards then you've seen a rider throwing away energy and any chance of winning the sprint.

Sometimes the rider will accelerate hard enough to try to gain a gap and to hit a high speed so quickly that it will be hard for anyone else to catch them or come past, other times the rider will make the acceleration to match that of others, to follow the first rider to jump or even just to get things started, encourage others to go and then follow them until close to the line (tactics again - its quite hard to fully separate the techniques and the tactics). Exactly how hard the initial acceleration or jump is will depend on the tactical needs at that moment.

Straight Lines

Another little bit of science (or geometry): the shortest distance between any two points is a straight line.

Watching a finishing sprint with riders veering across the road and weaving left to right might look spectacular, those who remember Adbu in the Tour de France know what I mean, but the fastest way to get to the finish line will always be the shortest distance and that is a straight line. This verges onto tactics but whenever possible the sprint should be as straight as possible to avoid travelling further than absolutely necessary.

In terms of technique sprinting straight is not quite as easy as it sounds, towards the last few metres of a sprint the rider may have reacher their absolute limit and even steering the bike can be difficult. Abdu (Djamolodin Abdoujaparov) famously pointed out that he always naturally drifted to the right, he didn't try to steer that way it was just that once into that final sprint it would happen and he felt he had little control over it.

Sprinting in a straight line means that as well as concentrating on all the technical stuff above, concentrating on tactics and pushing to a level most athletes rarely if ever reach the rider must also concentrate on holding that line. It is worth it because it is the closest and therefore fastest way to the finish.

Technically being very well balanced and being relaxed even under extreme pressure make holding a straight line much easier. When watching other riders the sprinter still needs to know where they are aiming and a bit like cornering having a point to aim at, on or just beyond the finish line, will generally result in straighter sprints. After that it really does boil down to doing lots and lots of sprints, racing and in practice and (verging on to the training post to follow) being able to pull together all the techniques whilst right at the edge of ability is a skill best developed through specialist interval training.

A second kick

As a young racer wanting to know how to move into the top 6 rather than to 10 in road races I realised that I needed to sprint faster and I read anything I could get my hands on (there wasn't really very much back then). The one that had the biggest impact was an interview with Sean Kelly where he described how he had developed a second kick that could make all the difference in a tight finish.
I don't talk much about this at the time but I went out on my own and I worked on that technique during that winter and into the spring and won my first ever big bunch sprint in my first race of the spring (unfortunately it was a sprint for second place, but well inside that top 6).

A final lunge

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