Race Rule #1: Walden says: “Get on a wheel!” A variation: "Close the gap!"
Translation: Always, (always!) “Be in the draft.” (unless trying to break away, or trying to win the final few meters of the sprint).
Like all of Walden’s pithy phrases, there can be an entire art and science to discover the full meaning behind the words.
The Science: In this case, the physics of the equation are cut and dry – proper drafting saves up to 30% of the energy expended by another rider pedaling the same speed without drafting. This scientific fact succinctly explains the sole reason I am able to be a bike racer. If I can get my aerobic capacity to be only as much as 70% of the strongest riders, then I can finish the race… and if I can finish the race – get within 7 seconds of the finish line - then I have a good shot at winning – it is simple as that.
Turning the phrase differently, one might say that virtually every person in the race is better than me – by the conventional athletic standard of endurance anyway.
The Art: The science ends with the math, and the art begins with questions like “paint me a picture of the draft – where is it? How can you conserve the most energy? Does that require physical danger due to proximity?” Due to my weak aerobic capacity (my parents blame it on my Cesaerian birth – no squeeze of life to fully expand my lungs) I’ve been focused on finding the draft - or “wheelsucking” as it is commonly referred to by those with the luxury of not requiring this aid - for 30 years now.
Of my limited strengths, wheelsucking is my strongest. I intuitively know where the draft is – to the point where, on a training ride with a friend, if I “tune out” for a few seconds, I will often find myself suddenly “riding the hip” in a cross wind, and find my friend staring at me crossly as I absorb the energy that they have transferred to the air.
Getting on a wheel is the first step to finding the draft. However, depending on the shape of the rider, the angle of the wind, and the relationship of other riders, the most efficient draft may well be found to the left, right, or even somewhat back from the wheel in front of you. I don’t know the physics behind it, but some winds allow for efficient drafting and in a paceline or “peleton” of riders you may find rest periods of “riding the wheel” that are a true respite from the efforts of the race, where heart rates can drop 25 beats per minute. Other “airs” seem to suggest a more agile wind that resists the rider’s impetus in front of you and still manages to block your path. In these cases, you may only find a 10 beat per minute savings while drafting in a straight line pace line. I hate air like this…
Then there is “pack drafting” which has its own dynamics – especially on a criterium course, and especially on one in town where the wind can swirl and eddy from different directions between each cross street, with tall buildings deflecting the overall currents. Over the last season, I’ve tried to retrieve my intuitive and instinctual (blink) reactions to drafting into logical understanding with some limited success. What I’ve been able to observe:
1) Generally speaking “turbulence” or “buffeting” against your chest and arms is an explicit sign that you are in the draft – try to center that visceral feel on your sternum.
2) In large packs, the single best draft is in the “rear triangle” – near the back, but still connected to the 3 or 4 abreast portion of the pack. Sometimes I’ll find the perfect position: 3 riders in front, then two slightly forward left and right, and then I anchor between them with my front wheel parallel with their rear wheels. This is the ultimate wind shade and has allowed me to pass through 30, 40, even 50 miles of a criterium conserving energy the whole way. (See chart below – “perfect drafting”) “perfect drafting” in blue.. 3) The draft changes in the corners – in dead still air, the draft will be slightly outside the wheel in front of you, as the instantaneous velocity of the riders in front of you is in a vector toward the outside of the turn – e.g. ride outside the rider in front of you on corners when the air is still.
4) Learn to ride close to the wheel. (particularly when the pack is strung out) I tend to ride about 6 – 8 inches from the wheel when I’m not miserably suffering, and half that distance when I am suffering. Each inch closer gives another percentage of energy savings (and some increased risk.) Practices at the track with Walden were invaluable in learning this skill – riding 2 inches from the wheel in front of you traveling 25 mph on a bike with no brakes helps you to learn spacial relationships on the bike quickly.
5) Learn to estimate proximity without looking at the wheel in front of you. Walden would yell “Don’t look at the tire in front of you – Look Ahead!” as, ultimately, the reactions of the rider in front of you were largely dependent, and amplified by the motions 2, 3 or more riders ahead.
Sure - you can work on your strength and aerobic base and improve them by 10% if you are out of shape or 5% if you are in shape, or 1% if you are world class... or you can, with a bit of focus and practice, save 1% or 2% or 5% by adjusting your 'wind shade'. I'm constantly amazed (and perplexed) by scene after scene of Tour De France riders cruising along off a wheel. Sure - they are strong enough to do it (which is probably why they never learned it really well) but imagine the energy they are squandering that could be better saved to help a teammate, make a breakaway, or climb a hill...