Performance Tips: Metrics
The more you know about your bike the better. In order to gain as much strength and endurance while ensuring your knees do not give out, please consider becoming knowledgable about gears and gear-ratio's. This kind of information was state of the art when I first started racing 15 years ago. In those days, we had to do all of this figuring with our own heads; today, I've located Bicycle Gear Inch & Shifting Calculator that assists you in this process.For those who are unfamiliar with gear ratio's, the concept is simple. The number of teeth on your freewheel and chainring plus wheel diameter gives you your GI (Gear Inches). Knowing your gear inches translates into you knowing your shifting pattern. In essense, with one pedal stroke, you gear inches can tell you how far you can travel.
A second site I located also incorporates your crank length in determining gear ratio. Which, does make sense.
Another online calculator offers you an analysis of your drivetrain. With this program, you can see what the metrics are for the drivetrain on your hpv (bike, trike, etc), if it uses chain coupled sprockets with an optional shaft coupled pair of sprocketsets between the crank and the road. Schlumpf Mountain Drive (Type-I) and Speed Drive (Type-II) crank ratios are available modifiers in sprocketset #1. Three hub styles are accommodated, a single ratio or direct hub, a hub with up to 15 distinct ratios like the SRAM Spectro, and the Rohloff SpeedHub that has symmetrical ratios.
When on your bike, you are met with several forces. The main forces are gravity, inertia, friction, rolling reaistance, and (the big one that has world class cyclists in the hunt for the most aerodynamic toys) wind resistance. All of these forces work for and / or against you. Let's talk about gravity first.
Gravity
Gravity affects everything we do, and for a bike rider it is no different. Basically, gravity plays a big role when you encounter a hill. When you are riding up a hill, you have to oppose the pull of gravity while still dealing with the other forces that are acting on you. The steepness of the hill determines how much of the pull of gravity works against you. The same is true on the downhills too -- however, it works for you now.
Inertia
Inertia is only a problem to cyclists when starting from a dead stop. When accelerating from rest, inertia is the largest force encountered. Your body, the bike, and the wheels all want to stay at rest. In acceleration, the weight of the wheels affect acceleration three times as much as rider or bike wight, so one pound in a wheel feels and acts like three!
Inertia also affects a rider when braking, although the frequency of high speed braking is not high, and quality brakes offer sufficient stopping power. Because of this, stopping is usually not a problem to a cyclist. On the track, the turns are banked for a very important reason. The banking allows the riders to make the turns at full speed. If the corners were flat, it would be dificult if not impossible to remain upright around the turn due to Inertia. The banking offers the riders a centripital force to counter inertia, like a pendelum.
Friction
Friction is encountered when cycling in a few key areas. These are: wheel bearings, drivetrain, brakes, and wind. We'll talk about Wind resistance later. You are faced with friction in the wheel bearings, but if properly maintained, this is not a factor. The drivetrain of a bicycle, including the chain, gears, and shifting mechanisms, produces only a 1.5 efficiency drop, if properly lubricated and maintained. The brakes are the largest area where friction comes ino play. Brakes use various lever mechanisms to push a rubber pad against the side of the metal rim of the wheel. The rubber if the brake pad is hard but gummy, creating lots of friction which opposes the motion of the wheel and slows it down.
Rolling Resistance
Rolling resistance is a result of the compression of either the wheel or the ground or both. This gets tricky, so keep with the breakaway here. When a wheel rolls on a surface, both the wheel and surface compress. This causes the point of instantaneous rolling to be slightly ahead of where it usually is, which is directly below the center of the wheel. This sets up a compression forca and a rebound force. When the point of rolling compresses the ground/wheel, the forces are higher than in the rebound stage due to the internal friction of the materials. This sets up a torque which we call rolling resistance. Think of walking in sand. You lose a lot of energy walking in soft sand because of this type of resistance.
To make matters even more interesting, every tire has different rolling resistance. Indeed, there is a lot riding on your tires. Picking the right tire may make the difference in your next race. John Lafford tested Rolling Resistance of different tires and found the Hutchinson 600 x 28A as the most efficient.
Wind Resistance
Here is the no brainer: wind is the biggest factor. Aerodynamics are the key for any competitive road or track cyclist. The airflow over a cyclist, the spokes of the wheel, and the bike itself -- this creates relatively high wind resistance. Wind tunnel research has created many improvements in design of parts and in formulating aerodynamic positions.
Every cyclist who has ever pedaled into a stiff headwind knows about wind resistance. It's exhausting! In order to move forward, the cyclist must push through the mass of air in front of her. This takes energy. Aerodynmaic efficiency--a streamlined shape that cuts through the air more smoothly--enables a cyclist to travel much faster, with less effort. But the faster the cyclist goes, the more wind resistance he experiences, and the more energy he must exert to overcome it. When racing cyclists aim to reach high speeds, they focus not only on greater power, which has its human limitations, but also on greater aerodynamic efficiency.
Aerodynamic drag consists of two forces: air pressure drag and direct friction (also known as surface friction or skin friction). A blunt, irregular object disturbs the air flowing around it, forcing the air to separate from the object's surface. Low pressure regions from behind the object result in a pressure drag against the object. With high pressure in the front, and low pressure behind, the cyclist is literally being pulled backwards. Streamlined designs help the air close more smoothly around these bodies and reduce pressure drag. Direct friction occurs when wind comes into contact with the outer surface of the rider and the bicycle. Racing cyclists often wear "skinsuits" in order to reduce direct friction. Direction friction is less of a factor than air pressure drag.
On a flat road, aerodynamic drag is by far the greatest barrier to a cyclist's speed, accounting for 70 to 90 percent of the resistance felt when pedaling. The only greater obstacle is climbing up a hill: the effort needed to pedal a bike uphill against the force of gravity far outweighs the effect of wind resistance.
On the right, we can see the power required to go 30 mph using a standard 32 spoke wheel versus various Phonak Team Zipp wheels at different wind angles.
Likely it is this wind resistance factor that has resulted in the largest number of studies. Specifically, aerodynamics, or the ability to reduce aerodynamic drag, is one of the primary concerns of a serious time trial racer to a touring cyclist. At top speed, aerodynamic drag consumes approximately 75% of the power that you produce on your bike. For this reason, increasing aerodynamic efficiency is often referred to as "free speed", which is hardly free as it usually costs.
In battling wind resistence, you must define and refine your aero positioning.
Here is what you've been waiting for: The key elements of a good aero position are . . .1. Horizontal torso
So, let's start by defining your "horizontal torso". . . have your chest, or better yet, your back parallel to the ground. This is the most tasty aero-ingredient of 'em all. This results in large magnitude changes in your aerodynamic drag.Unfortunately, it may be the most difficult to achieve, because as you approach this position, your thighs start to hit your torso. This interference imposes limits on your body's aerodynamic position, but is due to traditional bike geometry (i.e.; seat tube angles of 73 to 75 degrees).
What has helped me is to stop looking ahead and look down. I place my nose directly over my stem while I look at the stem. This not only decreases my drag but gives my neck a break.
Others comment on other techniques (ie, go to a more forward position seat but results in an unbalanced bike, or to buy a frame that is designed to be ridden in a forward position.
2. Narrowly spaced elbow pads
Narrow elbows are an essential detail of an aero position. If you got aerobars, make sure that the elbow pads are more closer than farther apart. However, the magnitude of improvement is much less than what is achieved by adopting a horizontal torso position. Research conducted by Boone Lennon has shown that subtle changes in elbow width and aero bar angle may have significant effects on drag. This research was performed on traditional geometry bikes, with the torso adopting the characteristic cupped shape, and probably illustrates the need to block air flow out of the torso area. More recent data on riders in a horizontal torso position shows much less effect from these variables. I do not believe these two findings are contradictory, rather, they indicate that once the torso is horizontal there is little you can do to improve or impair aerodynamic drag.
3. Aero Bar Positioning
Lest not be confused: horizontal torso does not translate into horizontal aero bars -- oh no, studies indicate that somewhere between 30 to 45 degree tilt upright of the bars actually decreases the aerodynamic drag as when the aero bars are horizontal the air is directed toward the stomach; when litled, the air travels through. Let's look at this figure for more details:
4. Knee Width
Knee width can actually change aerodynamic drag by up to half a pound. Pedaling with your knees close to the top tube is an essential part of good aerodynamics.
5. Water Bottle Placement
If you have one or two, keep the bottles on the frame -- a drink bottle on the frame actually provides an advantage particularly with strong side winds. One explanation is that the drink bottle provides a "sail effect" that acts to reduce drag (Source: Analytic Cycling). This means do not place one behind your seat (Oops, I did this for one year in the late 80's when it was the in thing.)6. AeroPak
Do not use an aeropak or other strap to back fueling system: it is better to keep your water bottles on your bike as a strong headwind with an aeropak creates a great deal aerodynamic drag; much less drag in strong side winds (Source: Analytic Cycling). This fact, as well as the "no water bottle behind seat" sends one strong message: The more turbulent the air behind the bike is, the greater the drag coefficient.7. Ride on Drops
Ride on the drops as much as possible. I suggest "training" your body to do this. I notice a 1 - 1.5 km/h increase in my speed just by going on the drops.8. Zipper Jersey
Zipper that Jersey -- it does make a lot of difference.9. Draft and then Draft Some More
At 20 mph, drafting a single rider reduced energy requirements (measured by VO2 needs) by 18% and at 25 mph by 27%. In order to benefit from drafting, you've got to be in the drafting bubble behind the cyclist immediately in front of you. And in a crosswind the bubble will NOT be directly behind the rider in front but will be some angle away from them. The effectiveness of this bubble decreases with the distance, being the greatest if you draft closely and falling off until there is minimal benefit at 5 or 6 feet. The important fact is that you will get some benefit 3 feet, or even 4 feet, back - and it’s a lot safer than being directly on the rear wheel of the rider in front of you.The rider being drafted also gains a slight advantage. This is explained by the fact that the low pressure behind the lead rider is increased in a pace line, giving the leader a slight "nudge" due to the pressure differential between the high pressure ahead and the low pressure behind. This is why a NASCAR racing car will go 1-2 mph faster when being drafted.
10. Test Yourself Out
Most of the information known is based on wind tunnel testing. I would recommend you: o do this proceed as follows:
- Find a steep hill
- Make a chalk mark at the top
- Starting from the chalk mark, allow the bike to roll forwards and accelerate due to the effect of gravity. Avoid scooting the bike forwards, maintain a constant position, do not pedal or touch the brakes
- After the bike has reached the valley below and slowed to the point where you can no longer balance and must either pedal or put your foot down. Make a chalk mark at the point where the bike comes to a halt
- Repeat this procedure several times alternately using tri-bars at 45 degrees or level. If you have used blue chalk to indicate stopping points for 45 degrees and red for level then you should begin to see two groups of chalk marks (technique described by Nigel Jones)
Source: http://home.hia.no/~stephens/aero.htm
Other Sources:
Rider Aero Study (Cobb)
Aero Helmets (Velonews)
Bicycle Aero Study (Lucas)
Velo Aerodynamics (Cramer)
Aerodynamics of Cycling (Landis)
Wind Tunnel Aerodynamics (IHPVA)
Literature on Bicycle Aerodynamics (Pivit)
Bicycle Aerodynamics (The Future Channel)
Testing of Bicycle Aerodynamics (Flanagan)
Slideshow - Bicycle Aerodynamics (Princeton)
Importance of Being Aero 1, 2002 (Velonews)
Importance of Being Aero 2, 2002 (Velonews)
Bicycle Aerodynamics, Web Site (Damon Rinard)
Science of Bicycle Aerodynamics (Exploratorium)
Discussion Forum - Bicycle Aerodynamics (Slowtwitch)
The time certainly has changed.Nowadays cyclists do not measure their distance and speed; cyclists, like Lance Armstrong, track watts, not miles per hour. Power output dominates the training of top cyclists like Armstrong because it's a much more accurate gauge of performance than speed (at the mercy of the wind), say experts.
Power never lies because it is a direct measure of the force applied to the bike (torque) that is converted into a measure of power output (watts). By measuring how many watts he expends on a mountain climb, Armstrong can develop a training program that duplicates those race efforts down to the watt. For the past seven years, Armstrong has used a $2,600 device called the SRM Powermeter, developed by German medical engineer Ulrich Schoberer in the late 1980s. The Powermeter measures deflection of the pedal crankarm using tiny strain gauges and converts the measures into watts on a handlebar computer that can store and download 70 hours worth of wattage (and heart rate) for analysis.
Did you know, track racers have pushed it over 2,000 watts for a few seconds. The average cyclist can barely light a 100-watt lamp. "Pro cyclists used to train according to how they felt," says David Cathcart, marketing director for CycleOps Performance Training Products, which makes a watt measurement device called Powertap. "Now it's all about metrics."
Power (does not take into account wind speed)
Estimate Your Cadence
In my days as a young cycling enthusiast, V02 Max was just becoming a big thing. At a University of Texas laboratory, five experienced cyclists worked out for at least 30 minutes at three different intensities - 25% V02 Max, 65% V02 Max, and 85% V02 Max. These three intensities correspond with about 40-50 per cent, 76 per cent, and 92 per cent of maximal heart rate, respectively. At each exercise level, scientists carefully studied the cyclists' rates of fat metabolism.
The trends in fat breakdown were clear. As exercise intensity increased from 25% V02 Max to 85% V02 Max, the amount of fat pouring out of the athletes' fat cells into their bloodstreams steadily declined. As a result, fat originating in fat cells made a huge contribution to the energy required for exercise at 25% V02 Max, providing about 80 per cent of the needed energy! By contrast, fat coming from fat cells contributed only 30-40 per cent of the total energy at 65% V02 Max and just 10-15 per cent of the total energy at 85% V02 Max.
Why did fat cells pay so little regard to the muscles' need for energy at 85% V02 Max? Actually, the chubby little cells were quite busy breaking down their internal fat molecules at that intensity; the real problem was in the blood. During high-intensity exercise, blood pours toward the muscles in flood-stage quantities but avoids the fat cells as much as possible. As a result, there's little blood available to 'pick up' fat from the fat cells, and the fat has to wait until after a workout is over to move into the bloodstream.
However, some additional fat is always locked away inside muscle cells. This second supply of fat doesn't have to move through the blood to get to the muscles, and it can provide a decent share of the fuel required for exercise. When the inside-muscle fat was factored in, fat contributed a steady 90 per cent of the required energy at 25% V02 Max, versus 50-60 per cent at 65% V02 Max.
V02 Max
Feet to cm
Pounds to Kilograms
Kpa to Pa then Pa to Mbars
Grams to Ounces
Time from Distance and Speed
Distance from Speed and Time
Speed from Distance and Time
Interesting. I've always thought of building our very own tandem bicycle. If anyone has tried, please drop me a line.
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