Power U

All About Power

What is power all about?

Power training has been used by professional cyclists for 20 years and has proven very effective. Coaches, exercise physiologists, and cyclists themselves rave about the benefits of power.

Power training is seen by cycling experts as extremely important to efficient fitness training for two reasons: First, the exactness of power measurement allows coaches to unequivocally measure fitness and gauge improvement. Second, many experts have seen power-based training actually work more efficiently than other methods, such as heart rate training.

“Power calculation provides an accurate picture of how efficiently your body is performing. You can compare one ride to another using power as the basis. Within any given ride you can easily evaluate performance based on power. At any point in the ride you can know if you are performing at, below, or above previous best performance. You will see significant improvement in performance when you begin training with power.”  Hunter Allen, power training expert

The efficiency, precision, and training advantages of power training are compelling: you get a lot of data that can be used not only to help you become more fit, but also to achieve maximum performance on the bike. 
Power data is instantaneous and power meters allow you to store in “ride files”. These files can then be analyzed on a computer after the ride. A whole industry of advanced power-analysis software and power-based cycling coaches use ride file data to help cyclists get better at every point of their rides. And while the data and coaching is very effective, some power training concepts are pretty esoteric: terms like “normalized power” and “TSS and IF” are now part of the lexicon 
of the advanced power-based cyclist. For most cyclists, the advanced stuff is much more than what’s needed to improve fitness while enjoying a bike ride.

What does power have to do with cycling?

Moving any object in opposition to a resistance requires power. For example, moving an automobile forward requires a big engine and a common measurement of the engine’s power is its horsepower. Moving a bicycle forward also requires power.

The unit of bicycle power measurement is the “watt”, the same units used for running electrical appliances. Watts are a measurable, objective quantity. In cycling, the watts expended by the cyclist are directly related to the force applied by the cyclist to move the bike and the speed at which the bike is moving.

It’s simple: the more power you produce and the longer the time you can sustain your power output, the better the cyclist you are and the faster you will go. Of course, there’s a lot more that can be done with power measurement (we’ll get to those things later) but the simple moment-to-moment measurement of your body’s power output tells 90% of the story of your cycling fitness. (What’s the other 10%? Your body weight; the less you weigh, the faster you’ll go for a given amount of power)

For example, let’s suppose two cyclists have the same total weight 
of rider and bike and are just starting a long hill climb. One of the cyclists is a man of average fitness and can generate about 200 watts for 10 minutes, more or less. The other is a pro cyclist: as it turns out, the pro can generate 400 watts for an hour or more. Not only will the pro climb the hill twice as fast as the other guy, he’ll be able to hold that pace for three times as long!

In order to generate watts on the bike a person must burn body energy (often stored as fat), must have a cardiovascular system that can provide sufficient oxygen to burn fat and circulate nutrients as rapidly as the muscles demand, and must have the physical strength needed to climb the hills and fight the wind. A good cycling fitness program will help improve all three of these dimensions.

Why are power-based fitness programs better than others?

There are two main types of training programs in use today that don’t require a power meter. They are “perceived exertion” and “heart rate zones”. There are many variants and combinations of these two.
Perceived exertion is your own, subjective perception of how hard you are working. The main drawback of this type of training is that your perception can be highly variable. The longer you cycle the more fatigued you become and the higher your perception of exertion becomes, even though nothing may have changed! There is something called the “Borg scale” that attempts to quantify your perception of exertion but it often takes years of trial and error to consistently evaluate your perceived rate of exertion.

In the 1990s heart rate monitors became a very popular way to measure cycling fitness. The principle is simple: the harder you work the faster your heart beats. Exercise scientists developed relationships between changes in heart rate and body energy (calories) burned, cardio fitness, and more. The problem is that while all of us have a heart in our body, no two hearts are alike, so the beat-beat-beat of different hearts are difficult to quantify precisely into comparative fitness levels.

Let’s look at what heart rate indicates. Primarily it tells you how hard your heart is pumping. As you put greater and greater strain on your heart by riding faster or using greater force, your heart has to pump faster to provide the oxygen for fat burning and blood flow to support those pumping legs. That would be great if those were the only factors that affected heart rate.
But heart rate is also affected by:
• Humidity
• Air temperature
• Stress in your life
• Your core body temperature

•  How rested you are

As your fitness improves, your heart rate often goes down, reflecting the greater efficiency of your cardiovascular system. 
So sorting out what has affected your heart rate from ride to ride can be difficult to assess. 
This is not to say that there is no value in heart rate and perceived exertion, but why take the ambiguous route when watts tells you the real story, the whole story in one little number?

If power measurement is so great why isn’t everyone using it?

So why doesn’t everyone use power measurement for cycling training? Every power-based training program requires the use of a power meter.  Traditional power meters have been around for many years and generally perform as advertised. However, their designs create some significant barriers for most cyclists:

  • Traditional power meters generally cost $1000-$5000
  • They require special wheels and hubs, or a special crank, or a 
custom bottom bracket, pedals, or even a precisely weighed bike chain
  • They weigh several hundred grams or more
  • They are inconvenient to move from bike to bike

So, despite the compelling benefits of power, widespread adoption of power-based fitness training has not occurred: the missing links have been an affordable, easy-to-install and easy-to-use power meter, and simple, easy-to-do workouts that are based on power measurement.

The iBike Newton fills-in these missing links. The iBike Newton has a fitness test that will tell you what level of fitness you are at now and provides a customized program to improve your fitness – a program that you can follow on-screen as you cycle. No other product in the world today does this.

How the iBike Newton measures power

The amount of power you expend at each instant of a bike ride is dependent on the speed at which you travel and the force you apply to the pedal.

Conventional power meters measure directly the amount of force you APPLY to the pedal. Power meters that measure applied forces are difficult to make, expensive, heavy, and not very flexible.

The iBike Newton measures directly the forces that OPPOSE your forward motion: wind, hills, acceleration, and friction. Measurement of opposing forces is much more economical to accomplish and, thanks to Newton’s Third Law:

Applied forces = opposing forces

The iBike Newton provides a very precise measurement of the F number required in the power equation, without all the limitations and cost of conventional power meters.

Power and Calorie Calculations

In bicycling, the power you expend on a bike is the product of two factors: the force on the pedal and the speed of the bike:

P= F x S

where F is the force on the pedals and S is the speed of the bike. By choosing the proper units of F and S, power will be measured in “watts”.

Power is a quantity that varies from instant to instant. For example, if you’re cycling hard at 20 mph and applying lots of force to the pedals you might be producing 300 watts (300W) of power. But, the instant you stop applying force to the pedals, F = 0 and your power drops instantly to zero. So, power can vary considerably throughout a ride and, in fact, even during a single rotation of the pedal crank. That’s why power curves look so jagged.

Work

An important and related measurement to power is “work”. Work is the amount of power you apply at each instant of during ride, multiplied by the time you apply that power, and that product summed up over the entire length of the ride.

Imagine it were possible to pedal with an absolutely smooth pedal stroke, for the entire length of the ride, so that there was no second-to-second variation in power. Then, the amount of work done in the ride would be

W = P xT

where W is the work (in kilojoules) done during the ride, P is the (constant) power expended during the ride, and T is the time length of the ride.

Work and Calories

The work done on a ride is the “output” of the cyclist’s legs and is measured in kilojoules (KJ). If the body is like an engine, then the legs are the pistons, driving the pedals.

Where does the fuel come from to cause the legs to pump? From food, of course; the body must burn food energy and stored fat in order to cause the legs to move the pedals.

Food has energy content and the amount of the energy contained in food is measured in calories. There is a simple conversion factor for converting work energy, measured in kilojoules, into food energy, measured in kilo-calories (Kcal, or most often just calories):

1Kcal = 4.18 KJ, generally expressed as

1 calorie of work = 4.18 KJ

Now, the food that we eat is converted into the force that moves the pedals. The body “burns” the food to cause the pedals to move, but the “combustion” process is not 100% efficient; in fact, it takes about 4 calories of food energy to produce 1 calorie of work energy at the legs. Said in another way, the body converts food energy into work energy with a 25% efficiency. To convert food calories into work calories then, the following relationship applies:

4 food calories = 1 work calorie

Finally, (!) we get to the thing we all want to know: HOW MANY CALORIES DID I BURN ON TODAY’S RIDE?:

Food calories burned = 1⁄4 work calories burned = 4.18 KJ work

Food calories burned = 1.05 x KJ work

Remember, the iBike Newton uses its power measurement capability to determine the KJ work of the ride; therefore, the iBike Newton also provides a very accurate measurement of the calories burned

How does the iBike Newton measure cycling fitness?

There are three simple and important dimensions to cycling fitness:

  • Strength: the maximum amount of effort your body can expend in short bursts to accelerate the bike in a sprint or climb a short, steep hill at high speed
  • Endurance: the ability of your body to work hard for ever-longer periods of time
  • Energy: the amount of calories you burn during a ride. The longer you ride and the harder you ride the more energy you will burn

The simplicity and elegance of power measurement is that each dimension of cycling fitness relates to a corresponding power measurement:

  • Strength: the maximum power in watts measured by your iBike Newton
  • Endurance: the average power in watts measured by your iBike Newton
  • Energy: the calories burned during your ride, measured by your iBike Newton

The iBike Newton reports maximum watts, average watts, and calories right on its screen, for each and every ride! So, you get easy and immediate feedback on your cycling fitness every time you ride.

As you pedal your bike you are producing power (measured in watts) and you are using your body’s energy (measured in calories or kilojoules) to do this. As you pedal your watts will fluctuate a great
deal based on changes in pedaling speed, hill slope and even minor changes in the road, wind, etc. You will see these wattage changes almost immediately on the screen of your power meter. Because of these moment-to-moment fluctuations a good overall measure of your fitness is taken over a period of time, say 10 minutes, when you can get a repeatable reading of average watts.

The iBike Newton includes a fitness test that lasts 10 minutes. At the end of this test the iBike assesses your average power output over the length of the ride and report out your fitness level. A variation of the 10 minute test is used by professional coaches and pro cyclists and provides a very accurate assessment of your overall cycling fitness.

Of course, measuring your fitness is one thing, but improving your fitness is quite another!

How is my fitness level determined?

Before we dive in to this question we have to introduce a concept
 that defines cycling fitness, not just in terms of raw power output but also in terms of body weight.

It’s easy to understand why weight is needed. Imagine a 220-pound man is riding next to a woman weighing 110 pounds (for the moment we’ll ignore the weight of their bikes). Suppose they are both riding up a hill at the same pace. Because the man is twice as heavy as the woman he must produce twice as many watts to hold the same pace!

Now, if the man could lose a few pounds but hold the same power output he would climb the hill faster. So, weight clearly must be a factor in assessing cycling fitness, especially if you want to go fast! This is where the concept of “watts per kilogram” comes in (the original power meter was made in Germany, so metric units are used in many power-based measurements). Let’s say the
 man averaged 200 watts during his hill climb, and he weighs 220 pounds. Converting his weight
 to kilograms we get 100 kg, so his watts per kilogram ratio would be 2.00 (200W / 100KG).

For the woman to hold the same pace she needs to produce only 100W (why? she only has 1⁄2 the weight to move up the hill!). And, if she rides up the hill at the man’s pace her watts per kilogram ratio is also 2.0.

HOWEVER, as you’ll learn once you start riding with your iBike Newton, for most cyclists it is EXTREMELY EASY for to produce 100W of power. In fact, the woman is being kind to her male cycling buddy and is holding way back on her power output. In fact, if she could also produce 200W on the uphill, her Watts/KG ratio would be 4.0 and she would rocket up the hill twice as fast as the man!

The conclusion is simple: the higher the ratio of your “watts per kilogram”, the better (and faster) the cyclist you are. In our example the woman is certainly more fit than the man, even through she does not use as much power to climb the hill at the man’s pace.

If you’re curious the conversion of pounds to kilograms is very simple:

2.2 pounds = 1.0 kilogram

Of course, your iBike Newton will do the arithmetic automatically so there’s no reason to remember the formula.

The iBike Newton has a built-in 10 minute fitness test that measures your watts-per-kilogram and interprets that result into a 1-10 fitness score. Ten is best!

How do I set up and run the fitness test on the iBike Newton?

We’ll assume that you have already set up and calibrated your iBike Newton according to the installation instructions. Also, we’ll assume that you’re familiar with the basic operation of your iBike Newton.

Before doing a fitness test weigh yourself— just your body weight, without the bike and equipment.

Once you have your body weight measured you can set up your iBike Newton for the fitness test.

What are the changes the body has to make to become a fitter cyclist?

We know that as your fitness improves, you will be cycling faster, harder, and longer. There are three specific things the body has to do to support this increased effort.

1. Efficient Fat Burning

To get the energy your body needs to support an increase in activity, your body must be trained to burn fat more efficiently. This will lead to an increase in your body’s endurance.

2. Increased Cardio Capacity

To get energy to the working muscles means your heart has to build strong pumping action and your veins and arteries need to increase their capacity. Your cardiovascular system needs to rise to the challenge that cycling harder and harder demands.

3. Build Stronger “Cycling Muscles”

All this efficient energy you are creating is supporting your cycling muscles to produce high levels of power for long periods of time. Building stronger and stronger cycling muscles will allow your body to produce even higher levels of energy that will result in higher wattage output for longer periods of time – to get you over a steep hill or to zoom by your competitors in a race. Obviously, your muscles can only become more powerful if the systems that support those muscles become more powerful – your fat burning increases, your cardiovascular systems becomes stronger, waste removal efficiency increases, etc. So the whole body in concert becomes more powerful.

Once I measure my fitness level, how do I get fitter?

Your iBike Newton fitness level is based on two factors. First, the average watts you sustained during your 10 minute ride. Second, your body weight.

By looking at your score and your w/kg ratio you can zero-in on the fitness improvement strategy that will work best for you:

Average watts measurements of 200 are not unusual. So, if your fitness level is low but your average watts are typical, then concentrating on weight loss is going to be a great way to improve your fitness.

If your body weight is reasonable but your watts are low then concentrating on strength improvement will help improve your fitness.

If you just feel kind of crummy and out of energy, then a cardio approach will help you get your overall fitness up to better levels. 
The iBike Newton workouts can help you lose weight, improve your cardiovascular fitness, and body strength. 
Based on your fitness score and your fitness objectives you can choose any of these three alternatives for a workout. 
Depending on your fitness improvement objectives, you’ll probably want to do a cardio workout some days and either fat burning or strength building on the other days. That’s a good way to start.

How does the iBike Newton help you improve fitness?

As is the case with any fitness improvement program, your body will respond favorably to exercise workouts. The trick is to design workouts that are effective, efficient, and fun.

The iBike Newton includes three types of workouts that will improve your overall cycling fitness in a very efficient manner: fat burning (to lose weight and make it easier to go faster); cardio (to improve the efficiency of your cardiovascular system and make it easier to ride for longer periods of time); and strength (to increase the maximum level of effort that you can expend for short durations).

As you get fitter by working on all three components – fat, cardio, and strength – you’ll be able to apply greater force to the pedals, for example, allowing you to take a steep hill with ease. As your leg strength improves, your maximum sustainable watts will improve.

Your endurance will increase, too, and the best measure of endurance is not power but total energy applied, that is, calories. The longer your rides, the more calories you will expend.

The iBike Newton measures average watts, maximum watts, and calories to give you a complete picture of your current fitness, and it provides power-based workouts to help you improve your fitness.

Adjusting the intensity of iBike Newton fitness workouts

Since iBike Newton workouts are based on the result of your fitness test it is important to be rested and to concentrate on maintaining an all out effort during your fitness test. Though an all-out effort is the goal you’re aiming for in the fitness test, in real life it’s never that easy. Maybe you’ve done your fitness test after a hard day of work, or the day after completing a big bike ride, or maybe you didn’t sleep so well. Obviously, your iBike Newton doesn’t know any of this but when you start to do fitness improvement workouts you’ll be able to tell quickly if the recommended workout levels are too easy or too hard for your current level of fitness. For each type of workout—fat , cardio, strength—and each fitness level – one through ten—there are two or three different levels of workouts – easier to harder.

The intensity of the workout can be adjusted from 0 to 2 in the Fit CFG screen.

When you are first starting out with an iBike Newton 
Fitness program, we recommend you select the 
easier workout the first time you go out on the
road. You’ll know quickly if this is the correct
 workout for you. If at the end of a good work-
out you should feel tired but not exhausted,
stressed but not severely weakened. If you can 
barely ride the bike then the workout is too
 hard. If after the workout you hardly feel as if you’ve been on a bike, then the workout is too easy.

If the workout is too easy, then the next time you go out, you can select the harder version of the fitness level.

How often should I repeat the fitness test? 


Assuming that you can do an iBike Newton workout three times a week, then we recommend you repeat the fitness test once a month.

Remember, you are helping your body with the iBike Newton workouts so weigh yourself prior to every fitness test. With any luck you’ll find that you have lost some weight. Make sure you put the correct body weight into the iBike Newton prior to each new test.

Over time, you’ll see that your wattage will go up and your weight will go down. Your watts per kilogram ratio will increase and along with it, your fitness score.

So, by following the simple iBike Newton workout regimen, your body will be stronger, you’ll have more energy and your weight will drop. How can cycling get better than that?

Fat as an energy source

Fat is a great energy source. Each gram of fat contains 9 Kilocalories of energy, whereas carbs contain 4 Kilocalories of energy per gram. This is why foods high in fat have much more calories.

If your body can use fat as an energy source, you will be using a more efficient fuel . . . and one with a greater supply. For example, a 150 pound male with 10% body fat has enough stored fat to provide 62,000 calories worth of energy. And as you already know by now, you can store a maximum of 1,500 calories of carbohydrates (which at in intense ride can be burned through in as little as two hours). As you get better at optimizing fat as an energy source, you will able to ride at more intense levels while still burning fat. It is possible to have a race type effort still be within the fat burning range.

Mixing up your workout routines

Many cyclists hop on the bike go out and try to set a new Personal Best every time. Or they might do the same type of ride every ride. Your iBike Newton has at least two intervals workouts in three different categories for each fitness level. These intervals when used together will help to work your fat burning, cardio, and strength. When you can increase your ability in these three categories, you will be an overall stronger cyclist with an increased endurance. In other words:

You will be more fit!

Racing: Developing Skills

The iBike Newton will  give you average and max data while you ride, but there’s much more valuable information within the actual file.  You access all this information through Isaac software.

Your power file can tell you how you’re fatiguing during intervals of different intensities, which in turn reveals specific areas within your cycling fitness that need attention.

For instance, you might have great average power for five-minute efforts but low power numbers for 30-minute efforts (as a triathlete, you want the opposite scenario). Looking at your ride file in Isaac can save you a tremendous amount of time and energy, by telling you when you’ve done enough work and when it’s time to rest or focus on your swim or run, but if the data never makes it out of the power meter it’s only marginally useful.

Endurance power management: Developing Skills

No matter how you are using your power – to survive a triathlon, win a race, or complete a long touring ride – you need to manage your power.  To manage your power you need to know what power your body is capable of.  There is a measurement called Functional Threshold Power, or FTP, which is a measure of the maximum power your body can sustain for one hour.

A triathlete needs to have energy left over after the cycling leg to complete the run so riding at 75% of FTP is about as far as they should push the limit.  A racer doesn’t need energy at the end of the race so they can ride closer to 100% of FTP.  An endurance ride should run at well below 75%.

The Newton has a fitness test lasting ten minutes which will give you a very good approximation of your FTP.  Your FTP will be reported in watts.  So let’s say your FTP is 100 watts.  If you are riding in a 20 mile race, you can ride pretty close to 100 watts throughout the race.  As a triathlete, you’d want to keep your watts to about 75 watts to allow you to go as fast as possible with enough energy to complete the last leg.  Of course, if you a doing a 100 mile tour across country, you’d want to keep your pace at about 50-60 watts.

You’ll want to experiment with watt levels to see how much you can push.

Speaking of push, you can exceed 100% of FTP but whenever you do you’re “burning matches”–that is, reducing your body’s overall capacity to work at high levels of effort.   Some forms of interval training are based on exceeding 100% FTP, but then pulling back to a recovery mode.  Pushing your limit but allowing your body to recover is how you get better.

One skill you’ll need to develop which will help you in all your riding is “cruise control”  — keeping steady watts.  The terrain can change and the wind can change but you should be able to keep a steady watt pace.  This means adjusting your speed, cadence, and gearing to keep that steady watt output.

Keep in mind that as you get better your FTP will increase.  You’ll want to retest your fitness level every four weeks.

Aerodynamic Positioning: Developing Skills

If you want to use your power to go faster or stay on the bike longer, you want to minimize the power you use to overcome aerodynamic drag.

The iBike Newton measures your aerodynamic drag, technically referred to as CdA (Coefficient of drag x frontal surface area).

The lower your CdA, the less resistance the wind will present to you.So, the trick is to reduce your CdA.

You can spend a fortune on “aero” bike frames, wheels, helmets, and more.  But how much good do they do?  Use the “Snapshot CdA” feature of the Newton to quantify the effect of equipment changes.

Also, your ride position has a HUGE effect on CdA.  What’s the best position for you?  Use the iBike Newton to experiment with your ride position, and find your best aerodynamic position on the bike.

Drafting: Developing Skills

As a cyclist you want to use your power efficiently.  Producing a high level of speed with low watt expenditure can husband your energy for a long ride–or the final break-away.

So knowing where you will get the greatest speed for the least amount of energy is very important.  Because of its  instantaneous response to environmental conditions, the iBike Newton can show you where the drafting sweet spot is.  By varying the location of your bike and maintaining bike speed, watch for the position where the Newton shows your tailwind is greatest–that is your drafting sweet-spot.

Minimizing Wasted Effort: Developing Skills

Maximizing cycling efficiency while minimizing energy consumption is an important skill for any cyclist.  Whether you want to ride for 100 miles or win a 20 mile race, you want your energy to be used for propulsion.  You’ll ride longer or faster if you aren’t wasting your watts.

There are three critical ways watts are wasted:  Uneven pedal stroke, excessive motion of the body on the bike, and braking.   The iBike Newton can help you maximize your efficiency in each of these.

Uneven pedal stroke does lots of nasty things: it makes it harder to hold steady watts, it moves your body in unbalanced ways, etc.  There is an ideal stroke which maximizes the power at each angle of the stroke.  iBike Newton PowerStroke software will tell you what your ideal pedal stroke looks like and what your actual pedal stroke is like.  This will give you the consciousness you need to work on the stroke.

Body motion on the bike is inevitable.  As you accelerate your body needs to catch up with the bike.  If you don’t hold a line well you’ll have undesireable body and handlebar motion.  iBike Newton Powerstoke software shows you how your body is moving on the bike.  Once again, consciousness of this motion will help train your body to minimize wasted motion and wasted watts.

Braking on turns, curves, and downhills are necessary but braking on turns and curves can be improved.  By knowing how much braking you are doing on turns, you can train yourself to be more efficient and reduce wasted watts.

The iBike Newton Interval Workout

For many years coaches have taught cyclists that a fast, efficient and productive way to improve cycling fitness is by the use of “intervals.” An interval is really a very simple thing: You simply cycle at a pace that is based on a targeted amount of power output.

In the interval the cyclist holds the target wattage for the prescribed time. At the end of the interval you back off to catch your breath and let your body recover. Both the time that you work hard and the time that you rest are predetermined.Work intervals can last anywhere from a few seconds all the way to ten minutes and more. After each interval there is a rest period and then the work interval is repeated.

Sometimes you’ll hold the same target wattage again in successive intervals and sometimes the interval might be lower or higher in watts or longer or shorter in time. It depends on the workout you’ve selected. A typical workout will consist of seven to twenty intervals and will last about an hour in total length.

A very important difference between power based workouts and old-fashioned cycling workouts is that neither speed nor cadence is key in power based workouts. Instead, what you do is to hold the target wattage for the prescribed work interval.

Let’s see how this works on the road.

If you live in a place that is flat you might need to bicycle at twenty miles and hour or more to hit and hold your target wattage. Conversely, if you live in the hills, climbing a steep hill at seven miles an hour could easily cause you to hit the same target wattage.

The beauty of iBike Newton workouts is that you can bicycle outdoors, get a good workout, and the iBike Newton will automatically adjust your pace no matter what your hill slope is, bike speed, or even wind speed. Using target watts as a guide you’ll be able to improve quickly with the iBike Newton.

The central principle of an iBike Newton workout is pedaling at a rate sufficient to hit and hold a “target wattage” for a specified amount of time. How does the iBike Newton determine what your target wattage should be? The answer is determined by the results of your fitness test. The fitness test lasts about twenty minutes, long enough to determine both your body’s overall level of fitness and to determine how much power your body is capable of sustaining for an extended period of time. Exercise scientists and cycling coaches have determined that “intervals” expressed as a percentage of this twenty-minute result (average power) provide an excellent means to safely improve your fitness and to do so in the most productive manner.

An interval is an extremely thing to understand: you pedal with sufficient effort to hit and hold a target wattage. You then hold that target wattage for a specific amount of time—a time interval. After the work interval you rest a bit by backing off your rate of pedaling to rest. Then, you work hard again—another interval. You repeat the pattern of work, rest, work, rest, etc. until the workout is over. That’s all there is to it!

Now that you know about interval training and the relationship of interval wattages to your fitness here’s how the iBike Newton creates customized workouts. There are three basic categories of interval workout: fat, cardio, and strength. And For each type of workout there are ten different fitness levels for each of those three alternatives.

Let’s take a look at fitness level three and see how the intervals work.

Fitness Level 3:

Fat burning: read across

60% 10:00 50% 5:00 65% 10:00 50% 5:00 65% 10:00
50% 15:00 65% 15:00 60% 15:00 70% 15:00

Cardio: read across

65% 12:00 70% 10:00 50% 8:00 70% 12:00 75% 10:00
80% 15:00 50% 5:00 85% 15:00 50% 5:00 80% 15:00

Strength:  read across

85% 10:00 80% 8:00 90% 10:00 40% 8:00 92% 10:00
90% 8:00 50% 8:00 95% 7:00 50% 8:00 90% 8:00 50% 8:00 95% 7:00
120% 3:00 40% 10:00 120% 3:00 40% 10:00 120% 3:00 40% 10:00 120% 3:00

In the table you’ll see numbers in boxes expressed as percentages and times.

Each row represents a complete workout, composed of “intervals”. The lower rows represent more challenging workouts. So, for fitness level three there are two intensities of fat burning and Cardio workouts, and three levels of Strength workouts.

Contained within each box is the specific information for the interval: the target wattage, expressed as a percentage of your fitness test wattage results, and the time that the target wattage should be held. So, for example, for the Fat Burning workout in the top row, the first interval’s goal is 60% for 10 minutes. The iBike Newton will take your wattage result from the 10 minute test, multiply it by 60%, and show that target wattage in the top screen of the fitness test window.

During the workout your iBike Newton screen will show the target wattage in the top window, your actual wattage in the middle window, and the time remaining for the interval in the bottom window. Just pedal your bike at the pace necessary to hold the watts!

As an example, if the measured result from a 10 minute fitness test was 200W average, and the cyclist scored a fitness score of “3’, then when the fat burning workout is selected the first interval the iBike Newton will instruct the cyclist to hold is 200W x 60% = 120W for 10 minutes. The next interval will be 200W x 50% = 100W for 5 minutes, and so on for the remaining 3 intervals. The total length of this workout is 10 + 5 +10 + 5 +10 = 40 minutes.

Between each work interval is a rest interval. Here you’ll continue to cycle but your target wattage will be lower. During the rest interval it will be easier to pedal and you’ll find that your legs and your lungs will have time to recover and rest.

Notice too that during your workouts you won’t see your bicycle speed displayed. You’ll only see your target watts and your actual watts. So, when you are climbing a hill, you’ll automatically back off on your speed to keep your watts from going too high.

Or, if you get a tailwind, you’ll need to pick up your speed somewhat to maintain your watts. It’s all very easy and natural.

Fat burning intervals tend to be lower wattage but longer in time. Cardio intervals tend to be a higher percentage of watts and a little longer in time. Strength building intervals require the most effort, sometimes more than 100% of your measured twenty minute power, but generally for short periods of time.

So, the iBike Newton workout very simply is a series of work intervals with rest intervals in between. At the end of your workout you should feel tired but also exhilarated. You’ve spent your time very wisely, very efficiently, and very productively with your iBike Newton.

Lose weight by biking slower.

As you may have noticed, the intervals in the “fat burning” category are not as difficult as the other two categories. A common misconception in cycling is that if you want to get faster, you always have to ride fast. While fast intense rides are a crucial part to cycling improvement, the slower fat burning rides can be just as important. Why is this?

When you exercise, blood moves to your muscles. The more intensely you exercise, the faster your heart will pump and the more blood will circulate through your body. Oxygen is carried in the blood and is the energy source for active muscles. When you are riding easy, your body has no problem delivering oxygen to your muscles: you are aerobic (with oxygen).

As your workout intensity goes up, your heart rate will go up. Your muscles are working harder and are demanding more oxygen. The problem is your body cannot process that much oxygen to feed the increased demand. Your muscles start going into an oxygen debt, and you become anaerobic (without oxygen).

So, why is it important for my muscles to have oxygen?

When your muscles have a good supply of oxygen they don’t need to draw energy from other sources (Carbohydrates: that pasta you had last night). They are getting all the energy from stored fat in your body. As the intensity increases, the amount your body can burn from stored fat decreases and the amount of carbohydrate based fuel increases. This means when you go to the gym and ride a very intense one hour spin class, you actually did not burn any fat.

Obviously burning fat is important for weight loss, but it’s also very important for endurance. Fat is a great energy source. Your body wants to burn fat as a fuel, but you have to teach it to do so. This is where the “fat burning” intervals pre-programmed into your iBike Newton come into play.

As you may notice, the intervals in “fat burning” are all around 50-65% of your 10 minute maximum power. At this level, you should still be aerobic (with oxygen) and you will be burning fat. As you do these workouts, you are feeding your body oxygen and telling it that it’s ok to burn fat. You should also notice that as the fitness levels increase, the intensity at which your body can burn fat will also increase. This means that at a higher intensity (and heart rate), you are still delivering oxygen to your muscles and your body is still burning fat. Since you are still storing the carbohydrates in your body for use at a higher intensity, your overall endurance will dramatically increase. You won’t feel like bonking (collapsing) after a 2 hour ride, and you won’t have to constantly be eating on the bike to keep fueling your body.

This table explains how an athlete with optimized aerobic system has an obvious advantage:

Fat burning Not-Optimized Fat burning Optimized
Calories per hour at HR of 150bpm 650 calories (example) 650 calories (example)
% of those calories from fat 35% 65%
Calories per hour from carbs 422 227

Now, your body can store a maximum of 1500 calories in stored carbohydrates. Once this is depleted you will start to burn muscles for
fuel and you are well on your way to the dreaded “bonk”. As you can see, in just about 3 hours the cyclist with the fat burning system NOT optimized will be hitting the wall unless they are constantly eating on the bike. The cyclist on the right can ride for about 6 hours before burning through the stored carbohydrates, and more importantly can eat a couple energy bars during the ride and feel great at the end. Endurance has GREATLY improved.