Ask a range of riders and coaches what you can do with a cycling power meter (or
why you should buy one) and you will receive a real mix of responses ranging
from "nothing you can't do with a heart rate monitor" to "more than I can
explain, go read X, Y & Z".
Assuming the reader is asking because he realises there is at least some value in all of the fuss (there is no smoke without fire
- right? - and training with power is creating an awful lot of smoke right now,
especially from the professional peloton) he can certainly discount the first response. But assuming he
wants a faster answer than several web pages or a book will give him this article summarises what are in our opinion the top dozen reasons to embrace cycling
power meters and the power based training philosophy.
This is by no means the first article attempting to summarise the utility and benefits of training and racing with power but it may be the first
published on a site where the reader
can really understand some of the benefits through the examples of intuitive power models. Without further ado, here is our dozen reasons to invest in a power meter:
- Motivate yourself & compare yourself with others
So you rode as hard as you could the last 2 weeks and your average heart rate was 180. You think you're getting stronger, but the winds were lighter this week,
and it was hotter last week, so it's hard to tell.
Your friend also averages about 180bpm, but he's faster, and you know some of the professionals average
the same. Are any of these numbers meaningful or motivational? Probably not. Start
a power meter and you can see even the smallest changes in your performance from ride to ride, you will understand why some people are faster and how much work it would take to achieve their level
of fitness. You will start to think about goals in terms of power outputs, all of
which is incredibly motivational.
This is, in our opinion, the #1 reason to train with power. Plus, if you'd like to compare your power numbers, anonymously, with other
serious cyclists power output and see these statistics in graphical form take a
look at our
page - you need only complete a free
with CyclingPowerLab.com to upload your numbers.
- Execute better intervals
The most commonly stated reason for training with power instead of heart rate is
that heart rate response lags effort, which means it isn't a real time indicator
of intensity, which means it can be pretty useless for judging effort when you
execute short, high intensity training efforts commonly termed intervals. Why is
this important? Well, there is overwhelming evidence to suggest that interval
training works, that it's a very effective and efficient way to improve speed,
thus explaining why the majority of coaches will prescribe it and the majority
of serious racing cyclists will adopt it. Wattage, by comparison, is a real time
indicator of intensity so it takes the guesswork out of interval training
sessions. Levels of training intensity can be precisely defined as
Power Training Zones
and respected precisely, in real time, using a power meter.
- Pace yourself
they are fit enough a common reason why cyclists sometimes perform badly lies in pacing errors. It is so easy to start any event too hard - you are fresh, you are full of adrenaline,
and so is everyone else - so it's an understandable but never-the-less costly error. A time triallist who starts too fast is highly likely to deliver a slower time than he should be capable of and
a road racer who shows excessive enthusiasm at the least critical end of the race - the beginning - is just wasting valuable energy. Remembering what was said in point '2' about the
limitations of heart rate as a real time indicator of intensity only a power meter combined with an awareness of threshold power can serve as a reliable
tool to avoid that excessively fast start. More complex variable power or "optimal" pacing strategies can be executed with the aid of a power meter and the reader can
begin to understand or experiment with these using our
Variable Power Pacing Model
- Quantify the demands of events
Many relatively new cyclists ask "I want to ride road race X, but I can only average speed Y, is this good enough?" Unfortunately, because road races are mass start events where riders
benefit siginficantly from drafting, they will usually be run off faster than a single individual could ride and so the required level of fitness just cannot be expressed in terms of speed.
Likewise the average speeds that riders achieve in time trials are hugely dependent on the course and to a smaller extent the atmospheric and weather conditions. But think about event demands
in terms of power and we are getting somewhere. Ask a friendly rider what was their average power in road race X, what was their top minute power, their top 5 minute power, etc, etc, and the
event demands can be understood with a fine degree of detail such that anyone can set about testing their level of praparedness using a power meter. Turning to time trials and triathlon bike legs
we indicate the
that would be required to ride certain times given assumptions you can change.
- Set & pursue quantifiable goals
Having quantified the demands of your event in terms of power you &/or your coach will want to set about defining
equally quantifiable goals that should and will (if adequately specified and met) deliver your fitness
to the level required for success in whatever target events. Training in terms of heart rate or effort just cannot be as precise and for this reason the outcome will
be more random - but do you really want to leave things to chance when you are
putting so much effort into training? Training with power doesnt just promote quantifiable goals, it
allows us to break them down into precise chunks, to strive towards them, and to know constantly if we are on track. Remember that with a power meter all training is also equivalent to
- Understand your failures
Racing is brutal. It's about pushing others to the limits of their physical &/or mental abilities, then going beyond them, in this way you can prevail. But not
everybody can prevail, failure
is commonplace, and these failures should be embraced as a way to learn about yourself.
There is no better way to learn about your racing failures than with the data you can collect
with a power meter. If you were dropped at some point in the race you can go back and ask "what had been my minute power at that point?"..."what had been my 5 minute power?"...etc, etc.
Then you can identify which of these power outputs was at or above your known limits and identify that as the precise reason for your failure. You or your coach will then want to focus
on training that weakness and who knows - maybe next time you will prevail. Nothing but power data gives your this sort of diagnostic capability.
- Test your fitness in multiple dimensions
We have spoken above about
understanding the demands of events in terms such as "minute power" or "5 minute power" or "threshold power". In reality fitness is a continuum of abilities which
expresses your strengths as a cyclist across all durations from a short, all-out sprint to a long endurance
effort. Power data intepreted using suitable software such as "Training Peaks WKO+"
or "Golden Cheetah" allows you to study this continuum of fitness variously called a
"critical power" or "mean maximal power" curve. You can then test yourself in these multiple dimensions, identify weaknesses, train them, or
perhaps choose to disregard them
and train your strengths, the decision is yours. It is important to realise that there is an interrelationship between power output at specific durations and the
Monod Critical Power Model
can be used to understand this as well as predict your all important threshold power and threshold based training zones off of known power:duration tests.
- Monitor changes in your fitness
Ride and heart rate data is something that people download and upload and collect for...well...for fun, and for nostalgia, and because
todays training aids make sure they can. But power data is powerful. It's incredibly
valuable to monitor changes in your power output a.k.a. fitness through time: it confirms impovement; it confirms how much work you have still to do; it confirms the effectiveness of different
training programmes and of the coaches you might be paying. Power data is simply more worthy of the time and effort taken to treasure it.
- Measure your aerodynamic drag precisely
Cycling can be reduced to an equation - this website takes a lot of effort to stress the importance and the applications of that equation. You put some power in, then you take some away.
You take some away for rolling resistance, for mechnical resistance between the cranks and the rear wheel, for hills, for accelleration, and most importantly you take a lot away for
air resistance combined with wind effects. Then you are left with some speed. If you can record your speed and your power, and note down a few environmental parameters (like temperature and
air pressure from a weather site) you can figure out your aerodynamic drag - a LOT more cheaply and a LOT more
than you could ever hope to do it in a wind tunnel. Aerodynamics is massively
important to cycling fast and it's advisable for all competitive riders to test
their aerodynamic drag and then work to minimise it. Have a look at the
CdA Estimation (Chung) Model
to understaad how you can use a power meter and our
calculator to measure your aerodynamic drag.
- Identify training quality & specificity
In much the same way as a rider could study the "time in zone" particulars of his ride in terms of heart rate zones he can do the same in terms of time in power training zones - remembering
what we have said about power being a better indicator of intensity. But power, combined with cadence, is also more revealing. There is a difference between riding at high power with high
cadence and at high power with low cadence. Some events or courses will tend to rely upon one more than the other and it's important to train accordingly. The technique used to analyse this data is called
"Quadrant Analysis" and you can do it with a power meter plus either "Training Peaks WKO+" or "Golden Cheetah" software.
- Monitor energy requirements (calorie counting)
A cyclists power output is related to his oxygen consumption (at the high end,
his VO2max) because energy and oxygen mix and burn in well known ratios. For
this reason his energy expenditure can be estimated, with high accuracy, using
power data. Power, wattage, is afterall expressed in watts and a watt is simply
1 joule of energy expended in 1 second. OK, it's a little more complicated than
that, suffice to say that the best way to measure energy consumption outside of
a laboratory is with power data and if weight management (down, up or sideways) is your
goal then this is an added benefit of riding with a power meter. We expand on
this relationship in the
HR-VO2-Power Relationship Model.
- Compare actual & theoretical performance
We know that some pro riders and teams have employed sports scientists to model time trial courses using essentially the same theoretical power models available on this site. One of the advantages
for them is that they can predict a riders performance or evaluate it using estimated or known power data, and then focus on any irregulatities. Theoretical performance modelling has a lot to offer
the amateur rider as well. You really can break a course down, let's say a time trial or the
Etape du Tour, define segments and understand how fast you ought to be able to complete each
segment and the course as a whole...without ever having been there. To some this is fascinating, to others it is just useful, but all you need is a power meter to understand your abilities
Power Sector (Time Trial) Model
on this site.
Still want to go and read X & Y & Z? Fair enough, you've seen the light!
Here are some of the most established points of reference: