Below is the 2nd more in depth article on pacing and gear selection. I wrote this is 2 or 3 sittings, so I apologize if it seems to ramble on a bit. I feel there's some great info, and several good example analyzing the Ironman Wisconsin bike leg. Before the tentative TBC camp in May, I'll give a more in depth summary of the course looking at the file and possibly the files from a few other riders if I can get a hold of them.
Once again, I touch on several subject but wanted to focus mainly on pacing and equipment selection. I only use my own examples, because that's all I currently have available to make my point without breaking and copyright laws. I do have access to an Ironman Maryland race file, but I don;t think it's very useful to demonstrate pacing on hills. I'm not trying to boast about my performance. I actually made several key mistakes as you'll see that could have ruined my day. Among them include riding too aggressively up many of the hills and ending up with a higher VI that slowed my overall time. Remember, when you ride harder up a hill, you are forced in effect to ride a little slower on the flats and downhills. This is where you lose time. I also rode I believe 15-20 TSS too high for my level of fitness and paid for it on the run.
Let me add one thing to consider as you read this. How hard is riding 85-90% of FTP for 2-3 minutes? That's right at or just above 70.3 pace. It's not that hard. So why should hills be hard? The answer is, they shouldn't be.
Hills Are Easy – Part 2, Examples
Mike Girard 11-29-14
Here is the follow-up I promised. I wanted to give a few examples and better
explain gear selection, how gear ratios work and what equipment options there
are. Then I give a few specific rider
scenarios using my racing data from Ironman Wisconsin and Kansas 70.3 as well
as a sprint race I did in May and an Olympic race in July. We’ll look at mistakes I made in pacing,
things I did well, and then plug in data for 2 theoretical riders. Steelhead didn't really have any hills, so
I’m ignoring that race.
First let’s review what makes up a hill. Wind drag is minimal and rolling resistance
is relatively small and somewhat linear at those lower speeds, so let’s just
ignore those for now and focus on our enemy…. Gravity! Gravity is pulling us towards the center of
the earth, so to change our elevation, we need to perform work or expend
energy. The Amount of energy, depends on
our weight and the change in elevation.
Therefore, since energy is power applied over a period of time, to climb
faster, you need a higher power output.
In fact, it’s proportional to the rate of ascent. If you can climb to the top of a hill in 1
minute using 200 Watts, then with 400 watts, a rider the same weight will
travel at twice the speed and take approx. 30 seconds. Yes, it really is that simple.
Gear selection determines the RPM that you will pedal at a
given speed. These create ratios, just
the same way that using a wrench with a 2’ long handle will require ½ the force
of turning a bolt using a wrench with a 1’ long handle. But you will have to move the longer handle
twice the distance. The work performed
is the same, as its force applied times the distance traveled. But it feels easier as you muscles are
contracting ½ a hard. Meaning you can
engage fewer muscles. As you approach
maximal force you recruit and fatigue more and more muscles leaving fewer
available in reserve to do future work until they have recovered. Additionally, metabolically, you will shift
to using other less efficient energy systems and produce more byproducts. You body operate and can sustain higher
energy levels longer at lower intensities.
As you “dip into” your reserves at higher energy levels, you will reduce
the energy level you can sustain over the distance. To avoid hitting those reserves, you want to
choose a comfortable RPM for that power output.
Most riders do prefer a slightly lower cadence when sitting up and
climbing. But there’s no rule. Best to just ride what’s. But don't let your bike ride you. You need to ride at the cadence and power
level that allows you to have your best race.
So what gear ratio to use?
Here’s a link to a chart of cassette ratios for Shimano 10 speed
cassettes http://sheldonbrown.com/k10.shtml#shimano9 So you see there is a compromise. You can either have gears more closely spaced,
or have a wider range. Up front, the
gears are called chain rings and you can have 3 rings, 2 rings or even just a
single ring. Additionally, the cranksets
have different bolts patterns that allow different ranges of chainring
sizes. MTB cranks allow the smallest
rings, track bikes the largest rings and road & triathlon/TT bikes have a
wide range of options.
So how do gear work?
When you turn the cranks, you turn the chain rings which his connected to
the rear cassette by the chain. This turns
the rear wheel. So if the rear wheel is
2098mm (http://www.bikecalc.com/wheel_size_math)
and lets say you are riding a 52/13, which is a perfect 3:1 gear reduction,
then if you pedal at 90 RPM, the rear wheel will turn 270RPM. Therefore we take 290 RPM and multiply it by
2.98 meters (circumference of the tire) and you will travel 804.6 meters per
minute. Multiply that by 60 and you get
48,276meters or 48.3 kph or approx. 30mph.
Since these are ratios, if I reduce my speed to 15mph and don't shift
gears, I will be pedaling at 45RPM. To pedal at 90RPM at 15mph, I will need a
ratio of 1.5. This could be accomplished
for example by having a 42T small chain ring and selecting a 28T rear chain ring. Again, it’s the same as having a long wrench on
a bolt, and holding it 30” away from the bolt instead of 15” from the
bolt. Your hand will more twice the
distance pushing, but it will require ½ the force, but in both cases the same
work or energy required will be the same.
How does even pacing matter in a race? Here’s a screen shot of my predicted IMWI
race using 280 TSS and here’s a shot of my actual performance.
*** note, that there’s a 4 minute penalty in there for
drafting, so ride time was actually 5:03.
I believe I deleted the time pushing the bike in transition… or a volunteer
actually stopped it for me, which his possible knowing how awesome the
volunteers are there.***
Comparing the 2 charts, tells me that I should have gone approx. 7 minutes faster
if I had ridden more evenly. Now
realistically, you lose approx. 1 minute for the section in and out of
transition, probably 1 minute to eat, drink and take handoffs at aide stations,
and 1 minute braking for turns more than predicted. But that’s still 4 minutes just from more
even pacing! There are some
opportunities to save time by going slightly harder when you are moving more
slowly up hills or with a headwind and going slightly easier when you have a
tailwind or downhill. But otherwise, you
overall split will be more closely related to your average power, not you
normalized power. Normalized power reflects
the actual physical impact of the ride due to riding above the average. So riding 200W normalized for 60 minutes should
have the same impact as riding 200W average for 60 minutes, even if in first,
you rode only 180 Watts average. Guess which
split is faster? With some exception
(such as illogical things like sprinting downhill and riding easy uphill), it’s
going to always be the 200W average, not the 180W average, because you put out
more total energy.
Therefore, the goal in a time trial, putting aside specific
race tactics, is to “flatten the course”.
Meaning ride with as even of a power output as possible. To do this, while maintain a comfortable
pedaling cadence, you need the proper gear ratios. That brings us to equipment selection. How do you choose what gear ratios you need
for a given race? Why not always just
use a triple chain ring and wide ratio cassette? Like all things in life there are
compromises. Let’s start with determining the anticipated range of speeds for a
race. For this, again we’ll use the
subscription based service Best Bike Split (www.bestbikesplit.com). In my opinion, all coaches should be utilizing
this tool when they need to help their
athletes prepare and select equipment for a race. For the purpose of this article, we’ll just use
it to determine the range of speeds we’ll be riding at. Lets look more closely at the chart for the
same ride at IMWI:
We can see that with a power output of approx. 280 Watts, or
3.7 w/kg, I’ll will be climbing at 9-10mph on the steepest hills. On the descents, on just 4 occasions, I’ll
exceed 36mph. On this particular
descents, I’ll need to brake at the bottom of that hill, so it will reduce the
benefit of applying power for that short period over 35mph. On the other hand, a large amount of time will
be spent at 18-20mph on all of the rolling hills. , where you are between the large and small
chain rings.
So how do I use this information? I know that I want to stay over 80RPM, so using gear ratio calculators (http://www.bikecalc.com/speed_at_cadence
), a 38/28 will go 9mph at 82RPM. On the
opposite end, with a 52/11, I can ride up to 35mph at a comfortable 95RPM. I can
also ride down to 17mph in a 52-21 which will reduce the frequency that I drop
to the small ring. Also note, that it’s
best to avoid using the last 2 cogs to prevent a crossed chainline that will
drop drivetrain efficiency. So the 11
& 12T with the small ring and the 24&28T with the large ring should be
avoided.
Of course, most individuals competing an and Ironman, shouldn't
be riding at 3.7 w/kg up those climbs and expect to run well. What if you're a more typical rider? Let’s use a 170lb (77.3kg) Male with a FTP of
230Watts. Pretty squarely “middle of
pack”. Probably looking for a very solid
12:xx finish time. They might want to stay
under 2.7 w/kg. We can assume rolling
resistance and aerodynamic drag is somewhat linear at these low speeds, so
power output will be proportional to speed up a steep hill. So a rider at 3.7w/kg going 9mph up a hill,
would only go approx.. 6.5mph @ 2.7 w/kg. We will give this rider compact crank, with a
50T large ring and 34T small ring. That
should be a low enough gar correct?
Yes, if grinding up the hill at 70RPM is acceptable. What if this rider tried to hold 80RPM? They will be going 9mph… and that will
require 3.7w/kg. If their FTP is 3.0
w/kg, that’s 120% of FTP!
Another example for those making maybe a little less power,
riding over 6 hours, closer to 7 hours. Lets take a 130lb or 59kg female. Her FTP is 170Watts, so still very solid at
2.9 w/kg. It’s a longer race for her
overall, so let’s limit her to 2.6 w/kg or 86%, a higher zone 3 tempo pace. She
will be riding at 6.5mph up that hill.
She is more comfortable spinning at 80RPM up the hill. We now have a problem. That’s 7.5mph with a 34/28. So lets give her a triple crankset with a
50/39/30 chain rings. That puts her at
6.7mph up that hill at 80RPM. Perfect! This last example probably represents roughly
at least ½ of the field at that race.
One last example I give is a special case, but could
represent older athletes as well. I
passed this individual on my 2nd lap. They hung tough and nearly finished the race,
but did DNF. I suspect it wasn’t just
fitness and his size, but pacing and equipment selection contributed as
well. It probably wouldn't have made the
difference, but every little bit helps. This
rider was approx. 140kg. I think his
FTP was around 350W, so that’s 2.5 w/kg.
A safe strategy would have been 2.2w/kg up that hill. That’s 5.5mph. That’s 65RPM on a 30/28. In this case, the individual would have
wanted a long cage MTB derailleur and to choose an 11-32 cassette to get to
75RPM, or a 11-34 for 80RPM.
The key lesson is to make good equipment and pacing decision
real data, rather than relying on more subjective information such as the
experience of other riders. Just because
that’s what someone else does something, doesn't make it right. Never be afraid to ask WHY. In this case, “why” would be why use a
34-28? Because that rider wanted to go
6.5mph @ 2.7 w/kg. Always choose the
tool necessary to get the job done within whatever restrictions you have and
consider re-evaluating those restrictions as well. Triathlon has been defined more by innovation
and trying new technologies based on science, rather than adhering to tradition
and myths.
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