- Morning, Trainiacs.
Just setting up a little setup for Instagram,
a little before and after, because on the bike here,
I just recently made some changes for, let me show you.
The crank set.
I changed the crank set on the Ventum to 165 length
crank arms, as opposed to 172 1/2,
the standard that it came with
and that a lot of tri bikes have historically come with.
But a lot of people are going
to these shorter crank lengths, myself included,
because this is a really easy way
to end up opening up your hips
so that you're fresher for the run
and more aerodynamic on the bike.
At the same bike effort levels,
you're gonna go faster on the bike and the run.
I'm gonna show you the difference.
It's good and it's good.
(energetic music)
All right, Trainiacs.
We are talking crank length.
Now, crank length is the length
from the center of your bottom bracket
to the center of the pedal.
Now, why a lot of people are going
to a shorter crank length, where a lot of triathlon bikes
and bikes in general have been getting shipped out
historically with a 172.5 mil crank length
to a 165, a 160, a 155 crank length,
is because it ends up opening up the hips.
It takes a little bit of pressure off the lower back.
It allows athletes to raise up their saddle height
and get lower.
Now when I put out that video that I shot this morning
on Instagram, just today, it caused some
of the most comments of any post I've ever done,
because people have a lot of opinions, both good and bad,
about crank length.
So let's talk about it.
So let's talk function.
What happens when you change your crank length
from shorter to longer or longer to shorter?
Well, there's one study that I found
called "The Effect of Crank Length
"On Joint-Specific Power During Maximal Cycling."
And this was done in 2011, and what it said essentially,
was that crank length does not play a role in power.
So whether you do a shorter crank length
or a longer crank length, you're going to be able
to produce the same power.
Great, we've got options, and it's not going
to affect our performance.
Another study, done in 2017, called
"Acute Effects of Small Changes in Crank Length
"on Gross Efficiency and Pedaling Technique
"During Sub-maximal Cycling," essentially looking at,
does crank length affect how efficient we are?
And what this found is that crank length
doesn't really change much with regards to efficiency.
So it's not like we have to work any harder
or easier, depending on how our crank length goes.
But there's more torque placed on our joints
with a longer crank length.
So the bottom line is that what we know,
is that shorter, longer crank lengths,
as far as functionally what we put out with power
and how it really affects our heart rate
and the amount of calories that we're burning,
it's not really going to have a big issue.
Whether we go shorter or longer doesn't matter
from that standpoint.
That's good.
Now, I wanna show you why going
to a shorter crank length has some benefits,
because if it's not going to affect our heart rate,
drive it up, and it's not going to affect our power,
drive it down, and we can perform the same
with just our data, I wanna show you how you can actually
get more aerodynamic on the bike, going faster
at the same power, and be fresher for the run,
going faster on the run with the same bike effort.
You don't have to dial it back.
So on the bottom here, we have my bike position directly
from the right at Half Ironman Puerto Rico.
On the top, we have the position from this morning.
On the bottom is 172.5 cranks, longer cranks, these cranks.
On the top is the 165 crank lengths.
And it's a very, very small change,
but essentially what happens is because the crank length
is longer, the distance that your leg
has to travel up ends up being greater
with a longer crank length, which then ends up narrowing up
the angle between your body and your leg.
So you end up basically crunching a little bit more
than with these shorter crank lengths,
because with the shorter crank lengths,
your leg doesn't have to travel up so high.
Your knee doesn't have to travel up so high.
So that angle ends up being a little bit wider.
So we see at the bottom, angle is about 41,
at the top, it's about 43.
And that more open position, it ends up tiring out your legs
more evenly on your quads and your hamstrings,
so you're less likely to have cramps
when you get onto the run.
The next reason you'd want to shorten your crank lengths
is so that you can get more aerodynamic.
And how that happens is, because your crank lengths
are shorter, you end up having to raise your saddle height
the distance of the shortened crank length.
So in this case, I had to raise my saddle height
seven and a half millimeters, so that my foot can pass
at the bottom of the pedal stroke with the same bend.
But then, what that results in is,
if the pads for your elbows are in the same position,
with a saddle height that's higher,
you're going to end up being shallower that way,
as opposed to angled up that way a little bit more,
and that's going to end up tucking in behind my head
a little bit better.
So what you can see is that basically,
just the little tuft of hair at the back of my head
is sticking up over my body there,
whereas here, it's basically everything over top
of my ears.
So, you've ended up tucking your body
in a little bit better, into that channel
that's created by your torso,
and at the same time, opened up your hips.
So you're more aero and going to be fresher for the run.
It's a good deal.
Now, is this something that every single triathlete
needs to do?
If you've just bought your first road bike,
your first tri bike, and you're like,
oh, well now Taren says that I have
to change my crank lengths, not really.
It can be a pretty pricey upgrade.
Could be anywhere from $200 to $800, $900,
depending on your group set.
In addition to that, this isn't really something
that you wanna do yourself.
I had to take my bike into the shop,
because there are special tools to take apart a crank set,
and I dropped it off, had to pay for it,
come back, and it's not an easy change.
So we're talking hundreds of dollars to make this change.
Now, if you are a more established triathlete
and you're looking to buy speed
and you have gone through purchasing wheels,
you've gone through a bike fit,
you already have an upgraded aero helmet,
and you're looking for every single area
that you can get more aerodynamic
and buy as many additional watts
and get yourself aerodynamic and fresh for the bike,
this is a good place to do it
because 85% of the drag that is created
with us going through the air is from our body.
So we have to make our body position
as narrow and as low as possible
while still being comfortable.
And this is one of the only ways to do that.
Because a lot of the other ways,
where we're just getting more aero,
involves scrunching ourselves, getting lower,
being more flexible.
In this case, it requires actually less flexibility
to be more aero.
So, if you're looking for those marginal gains
and you don't mind spending a little bit of dough,
look at changing your crank length.
From all of the comments that we got on Instagram,
somebody said it best when he said,
"If you go 165, you never go back."
Check it out, Trainiacs.
There you go.
Thanks to Shimano for letting me replace this.
Later.