Category Archives: returing to triathlon

Aerodynamics and bike fit for speed

Some practical wisdom on endurance sports nutrition from the book is “The woman Triathlete“, reprinted with permission by Human Kinetics.

“How fast you finish the cycling portion of a race depends on the
power you’re able to produce during the ride. Ultimately, power output
depends on just two variables: force and speed. Very simply, it depends
on how hard you push and how fast you pedal. The three forces you need
to overcome to move forward are air resistance, rolling resistance,
and, on climbs, gravity. Because gravity and rolling resistance depend
on weight, most cyclists try to minimize weight. This is most easily
achieved by using a lighter bike and componentry, but these come at a
high cost. Rolling resistance also depends on the road surface, as well
as the make, thickness, and pressure of your tires. The biggest
resistive force, however, is air resistance, which is dependent on your
speed and frontal surface area. At 20 miles per hour on a flat road
(gravity is zero), rolling resistance makes up less than 25 percent of
the total resistance, while air resistance makes up more than 75
percent. The most effective way to reduce air resistance is to draft
behind (or even next to) another rider. For a triathlete without the
option to draft (drafting is not permitted in most amateur triathlon
racing
), reducing frontal area has the greatest effect on performance.
Aerodynamic equipment–such as bike frames with tear-shaped tubes,
deep-dish wheels and discs, narrow water bottles, tight skin suits, and
streamlined helmets–can reduce some of the frontal area. However, a
rider’s body is by far the biggest obstacle. Bike fit for a triathlete
is therefore optimized with biomechanical fit and aerodynamic
positioning; many triathletes even choose to ride a less comfortable
setup in favor of better aerodynamics. Keep in mind, though, that a
comfortable setup that incorporates aerodynamics will usually result in
increased power output. Because road cyclists are allowed to draft,
they tend to place greater importance on biomechanical fit, comfort,
and handling of the bike than triathletes do, but triathletes would be
well served in finding a comfortable setup.

It is relatively
easy to adjust a traditional bike fit to a more aerodynamic fit. The
most cost-effective investment is a set of aerobars. Better yet, using
an ergo-stem along with your aerobars will allow you to more completely
adjust the position of your handlebars. A second seat post and saddle
combination will allow you to quickly move back and forth between a
road position and a time trial position with just one bike frame.
Because a traditional road bike fit often results in better (i.e.,
easier) handling of the bike, it is useful to be able to switch back
and forth between setups. You can convert your bike to match your
workout–aerodynamic position for solo efforts and time trials or a
traditional bike fit for group rides and hilly routes. Before you
adjust your bike fit to a more aerodynamic position, measure (and mark
with tape) how your bike is set up. It is always a good idea to have
the option of going back to a position that already works for you. Once
you have the necessary measurements, move your saddle forward one or
two centimeters. Because this reduces the distance from your saddle to
the bottom bracket, you may also need to move the saddle up (usually
about half the distance that you moved it forward). Now check your
reach by leaning forward into the aerobars. The front of your shoulders
should be aligned vertically with the back of your elbows. This
position allows you to rely on the skeletal rather than muscular
support of your upper arms for the weight of the upper body. Your
comfort and flexibility should determine the height of the handlebars
relative to the saddle. For example, if your hamstrings feel tight,
your handlebars need to be moved higher. Most likely, your cleat
position and your saddle tilt can remain in the same position as they
were in before.

No matter how aerodynamic you want to be,
injury prevention and comfort should be your main concerns with regard
to fit. Your knee rotates through many cycles on a ride–in just one
hour of racing at 90 revolutions per minute, you are completing 5,400
rotations per leg! If your bike is not properly fit to your
biomechanics, you will be at high risk for injury. Also, if you are
uncomfortable on the bike, you may become distracted by repetitive
twinges instead of being able to focus on your effort. Because a proper
bike fit is critical, you should be fit at a reputable triathlon or
cycling shop, by a certified fit specialist, or by a coach or physical
therapist who has experience in bike fit. A proper bike fit should
always include setting up your cleats (on the bottom of your shoes) in
the proper position: If your knee is restricted to the wrong range
through each pedal cycle, you’re almost guaranteed injury. Athletes
looking to be very competitive in triathlon should consider being fit
by a professional fit specialist who will take into account every
aspect of their biomechanics when adjusting their position. Look for
someone who specializes in triathlon-specific fitting, and expect to
pay $50 to $100 for the service (and anywhere from $200 to $1,000 for
services that include power output measurement or wind tunnel testing).

Even with a good bike fit, you may find that you are
uncomfortable on your saddle at times. If you experience this, consider
the following:

  • Never wear anything under your cycling shorts. The shorts are
    designed so that there are no seams in sensitive areas. Wearing
    undergarments adds those seams back between you and your saddle. Also,
    make sure you buy women’s shorts to ensure a proper fit.
  • Wash your shorts after each ride to avoid infections.
  • Use a chamois cream or ointment to prevent saddle sores and
    chafing. Apply it to both your body and the shorts for maximum
    protection.
  • Use a women-specific saddle. They are designed to support the wider sit bones of a woman’s body and provide increased comfort.”

Top 3 bike selection steps for triathletes

Having the right bike for you and having it dialed in can make a lot of difference.  It will make the ride performance better all around.  It can also help prevent injuries associated with cycling and cycling position.  This excellent excerpt from Triathlon Workout Planner by John Mora reprinted with permission from Human Kinetics.

 

Selecting a bike

“If you’ve only recently been bitten by the triathlon
bug, the very first, most obvious symptom is an inexplicable need to
visit the nearest bicycle shop. Once you’re there, your symptoms might
progress toward writing out a check for a thousand bucks, or worse,
taking out the plastic. Hold on there. You might not need to shell out
four figures at this point.

If you currently own a bicycle and just want to finish
your first triathlon, you might be able to get by with what you have
until you’re sure you’ll be a lifelong multisport maniac. It’s not
uncommon for beginners to use a beat-up old road bike or a fat-tire
mountain bike for their first event, and there’s nothing wrong with
that. However, if you don’t have a bicycle (or can’t borrow one), then
you have no alternative but to look into buying a triathlon bicycle.
Also, if you’ve done a few triathlons and are looking for some advice
on making your first serious multisport bicycle purchase, the following
sections provide some guidance for you.

Tri-Bikes, Step by Step

Making your entry into the complicated world of cycling
equipment can be expensive and intimidating. Somewhere among the fancy
designs, shiny components, and black rubber is what you need. Without
some basic knowledge, a good understanding of your current needs, and a
clear vision of what lurks on your triathlon horizon, there’s a strong
chance that you’ll purchase the wrong bicycle.

Fear not. Here’s a step-by-step guide to making that
first big multisport purchase, with advice from triathlon bicycle
dealers, manufacturers, and coaches. Add to that some tales of woe from
professionals who can tell you (through their experience) what not to do when you’re making that big purchase, and you have no reason to panic.

Step 1: Set a Budget

Walking into a bicycle shop with no plan can mean
walking away with no money. Although most bike dealers will not
deliberately take advantage of an eager first-time buyer, by setting a
budget you are taking the first step toward controlling a situation
that might seem uncontrollable.

A cautionary word about overemphasizing equipment is
warranted. “Your best bet is buying a reasonably priced, entry-level
bike with a clip-on aero bar,” says cycling coach Bob Langan. “It all
comes to this: It’s not the seconds equipment will save you; it’s the
minutes a good aerodynamic position and proper training will.”

How much will you spend on your first triathlon bike?
Generally speaking, prices for entry-level racing bikes range from $900
to $1,400. Of course, the sky’s the limit on how much you can spend (if your bank account can handle it), but spending more than $1,400 is risky for two reasons:

1. You might not know what you need.

2. You might think you know what you need, but you might be wrong.

Does that mean you should go the other way and get the
cheapest two-wheeler you see on the dealer floor? No. Although the
frugal side of you might want to buy the cheapest Wal-Mart special you
can find, you’ll likely find it to be less than what you need. Better
to buy the most bike you can afford and be able to train and race with
comfortably, than have to start all over a few months down the road.

Step 2: Don’t Forget Accessories

One common mistake is excluding accessories from the
budget. Earmark $300 to $500 for accessories, more if you intend to
purchase optional equipment such as an aerodynamic disk, tri-spoke, or
deep-rim wheel. Some of the more basic bicycle accessories include the
following:

  • Frame pump
  • Patch kit
  • Spare tubes
  • Helmet
  • Clothing (shorts, jerseys, jacket)
  • Gloves
  • Cycling shoes (optional)
  • Clipless pedals (optional)
  • Aerobars (optional, but highly recommended)
  • Computer (optional)
  • Sunglasses (optional)

As you can imagine, your $900 bicycle purchase can run
well into four figures with the addition of these or other accessories.
Is all this stuff really necessary? Most of it is. You can’t race
without a helmet, and you need the additional comfort and safety that
cycling shorts, jerseys, gloves, and the other necessities afford you.

If you intend to transport your bicycle in your car, a
roof-mounted bicycle rack can run you well over $500. A less expensive
alternative is a trunk-mounted rack. Still cheaper is taking the wheels
off your bike and throwing it in the back seat or trunk.

In recent years, many bicycle manufacturers have included
clipless pedals, contraptions that attach your shoes to the bike for an
efficient, more comfortable pedal stroke, as basic equipment on
entry-level road bike models. This addition will save you close to $150
that you might have earmarked for this accessory. (If the bicycle
you’re interested in doesn’t include clipless pedals, it’s time to
start negotiating with your dealer.) Though many people fear being
attached to a bicycle with clipless pedals, you can get out of the
pedals at any time simply by extending your heel outward.

Cycling shoes are designed for use with clipless pedals.
Cycling shoes are stiff and transfer energy more directly to the
bicycle than do rubber pedals or toe straps. Cycling shoes vary widely
in price, from $100 on the low end to more than $200.

Aerobars help you slice through the wind. Better
aerodynamics with aerobars increases your speed and helps you save
energy for the run. As you train for longer distances, this accessory
will definitely fall out of the “optional” category and into the
“mandatory” list.

Speed Demon Fact

If you recall, Greg Lemond’s historic victory in the
1989 Tour de France came as a direct result of the performance
advantage of his triathlon aerobars. Wind tunnel testing has shown an
estimated average time savings of five minutes during an
Olympic-distance bike leg (40K) when a cyclist maintains an aerodynamic
position on aerobars. Other studies have shown that cyclists in a
proper aerodynamic position are more relaxed and experience decreased
heart rates.

Step 3: Understand the Choices and Know What You Need

Purchase a good racing bicycle that is versatile and
durable. Buying an entry-level racing bike that is upgradable can save
you time and money in the long term. For example, pioneering duathlete
Ken Souza’s first duathlon bicycle was a Nishiki International he
bought in 1982 for a scant $175. Though the bicycle served its initial
purpose, it was a touring model (a bicycle designed primarily for
casual riding) that Souza quickly outgrew. Yet the pioneering athlete
who put duathlons on the map continued to pour money into a pocket full
of holes. “It was ironic. I was spending all this money trying to
upgrade, trying to save a few dollars by not buying a racing bike. I
could have bought a real racing bike sooner if I hadn’t tried so hard
to upgrade a bike that wasn’t worth it.” So Souza’s experience makes an
important distinction—find a good upgradeable bicycle, but just be sure
it’s something that’s worth upgrading over a reasonable period of time,
You may very well outgrow an entry-level bicycle, but try and find
something that will last you for as long as possible.

Souza’s solution to his novice woes was one that you
might want to consider if the opportunity arises: “I bought a used
racing bike—a Vitus carbon fiber—from ex-pro Mark Montgomery. I think
that’s one of the smartest things a beginner can do. You’ll get
top-of-the-line gear, you can get a great deal, and it’s usually not
beat up.”

The Science of Cycling Position

Here’s another excellent excerpt reprinted with permission from Human Kinetics of High-Performance Cycling by Asker Jeukendrup

cycling performance“Throughout this chapter, we have used a set of reference values for aerodynamic drag area. Although these values represent good approximations to the drag area of a 70-kilogram (154-pound) rider in each position, those values are not fixed. Rather, a cyclist can influence his drag area in several ways. Riding with knees close to the centerline of the bicycle frame can reduce drag area by approximately 8 percent compared with riding with knees wide apart. This knee position will affect drag similarly whether the rider uses conventional racing handlebars or aerobars.

For riding with standard handlebars, arm position, including elbow bend and forearm alignment, can even more dramatically influence drag area. Bending the elbows allows the rider to lower his torso and thus reduce frontal area. Indeed, carefully positioned arms with the forearms horizontal and parallel to the bicycle can reduce drag area by up to 12 percent compared with widely positioned arms or straightened elbows. A wide-elbow position may result from poor technique, but it also may be due to poor bike fit and thus may not be within the control of the rider. Specifically, if the saddle-to-handlebar distance is too short, the rider may be forced to widen the arms so that they do not contact the legs. Consequently, drag area may be substantially increased because of a poorly fitted frame-stem-handlebar combination.

Optimal Time-Trial Position
Riders often ask, “How do I optimize my time-trial position?” The simple answer is, “Go to a wind tunnel and have your aerodynamic drag measured in various positions.” But, of course, not every cyclist has the opportunity to take part in wind-tunnel optimization.

As an alternative, we offer several suggestions that will help riders position themselves using only a trainer and a mirror or video camera. We recommend the following procedures to establish a preliminary position before wind-tunnel testing, and this often will result in a position that is within a few percentages of the optimal drag area.

Over the past 10 years, two very different approaches for optimizing aerodynamic position have been used. During the early 1990s, it was recommended that riders use a dedicated time-trial bicycle with a steep seat-tube angle (78 to 84 degrees). With bicycles like this, a low drag-area position could be achieved with a relatively formulaic procedure. Those positions are, at the present time, allowed for triathlons and by some national cycling federations. However, UCI rules currently prohibit forward seat positions. Within the current UCI rules, low drag-area positions can be achieved but the procedure is less formulaic and depends on individual morphological characteristics.

To achieve a low drag position with a forward seat position, start with your current road position. You achieve the aero position by “rolling” that position forward until the torso is horizontal. Specifically, the elbow pads should be lowered and the seat should be moved forward (and slightly up) so that the body rotates about the bottom bracket and the joint angles at the hip and knee are maintained. You can use a mirror or a video camera to assure yourself that your torso is horizontal and that your relative hip, knee, and ankle angles are maintained during this procedure. This procedure usually results in seat positions that require a bicycle seat-tube angle of 78 to 84 degrees depending on body type. Taller or more slender riders tend to require less steep seat-tube angles, whereas shorter or more muscular riders require greater seat-tube angles to achieve a horizontal torso. You can achieve a similar position using a standard frame with a forward-angled seat post and a long stem. However, that configuration may result in a bicycle that may not handle well. If you are to use a forward position, we recommend that the frame be specifically designed for proper handling with that position.

Once you have achieved the horizontal torso position, it has been our experience that details regarding positioning of the arms are less critical. Changing elbow-pad width (center to center) from 11 to 14 centimeters has almost no effect on total drag area, but wider positions (greater than 20 centimeters) can increase drag area by 0 to 3 percent. Similarly, arm angles (measured from horizontal) of 5 to 40 degrees have very little influence (0 to 3 percent) on drag area. The small effect of these changes on drag area suggests that, once a horizontal torso position is established, differences in arm position only affect the location of the arm’s frontal area but do not significantly affect coefficient of drag or total drag area.

Cyclists must accomplish aerodynamic positioning for bicycles with conventional seat-tube angles with more subtlety. Initially, riders must learn to roll their hips over as described by Lemond and Gordis (1987). This posture can be difficult to adopt, but it is an essential element of a low drag-area position with a standard bicycle. The level to which the elbow pads can be lowered will be limited by contact between thigh and torso (which will occur at acute hip angles). Because the elbow pads cannot be radically lowered, frontal area cannot be dramatically reduced for a conventional seat-tube-angle bicycle. Rather, reductions in drag area must be accomplished with careful positioning of the hands, arms, and shoulders to reduce the coefficient of drag. Specifically, the width of the hands and elbows and the angle of the forearms are critical elements that, in an optimal configuration, act to channel airflow around the rider’s torso. Additionally, the contour of the rider’s shoulders can influence the point at which airflow separates. Rounding the shoulders and rolling them forward (i.e., protraction and downward rotation of the shoulder joint) can allow airflow to stay attached further around the rider’s body and thereby reduce pressure drag. The combined effects of redirecting (arm and hand position) and smoothing (shoulder contour) airflow around the body can reduce drag area by 10 to 20 percent.

Comfort and Power
Optimized aerodynamic positions can be uncomfortable in two ways. First, by rotating the hips forward, the cyclist places pressure directly on highly sensitive areas. Additional seat padding may help to distribute that pressure but probably will not completely eliminate the discomfort. Some riders try to alleviate this problem by tilting the nose of the saddle down, but that approach will result in a tendency for the rider to slide forward, off of the saddle. That sliding force must be restrained with forces produced at the shoulders and arms that can become fatigued very quickly. Second, riders may experience muscle soreness or strain in the muscles that extend the neck. This discomfort will be reduced with training and can be ameliorated with stretching and massage.

Riders often express concern that changes in position may compromise their power or efficiency. Heil et al. (1995) investigated the effects of seat-tube angle on metabolic efficiency and reported that efficiency was significantly greater with 83- and 90-degree seat-tube angles than with a 69-degree seat-tube angle. Similarly, Price and Donne (1997) reported that efficiency with an 80-degree seat-tube angle was higher than that with 68 or 74 degrees. Thus, steep seat-tube-angle bicycles should not decrease metabolic efficiency and, indeed, may improve efficiency. Conversely, Heil et al. (1997) reported that reductions in mean hip angle increased cardiovascular stress for a given power output. Such decreases in hip angle often occur when riders attempt to reduce their frontal area by lowering their elbows excessively. Therefore, you must exercise caution when adjusting your position to avoid excessive hip flexion.

Summary
This exploration has produced several useful findings for the cyclist. Typical cycling positions exhibit drag-area values that range from 0.48 to 0.27 meter squared, which can mean up to a 20 percent difference in velocity for a given power output. Surprisingly, the proportional difference in velocity is nearly independent of power, suggesting that novice and elite cyclists will realize similar benefits from improved aerodynamic positioning. When a rider is cycling uphill, differences in cycling velocity related to drag area are markedly reduced but are still substantial for less steep grades and for high power outputs. Even though the effect of drag area is reduced during uphill cycling, adopting a standing position is not recommended because of increases in metabolic energy expenditure. Finally, for any given cycling position, drag area can be affected by the position of the knees, elbows, arms, and shoulders.”