Should You Ride A Shorter Crank? | Choosing Your Bike Crank Length

Should You Ride A Shorter Crank? | Choosing Your Bike Crank Length


– Crank length is an aspect of our bike that we very often overlook. In fact, it’s entirely possible that many of you watching this might not even be aware of the
crank lengths on your bike. And understandably so, because
we’re quite happy to ride whatever comes fitted to
the bike in the first place. And yet crank length can affect how effectively we
generate a pedaling force. Plus, it could be argued that crank length is one of the most important factors of a comfortable and efficient bike fit, behind, say, the very obvious
of, say, our saddle height. And despite this, many of
you might not even be aware that cranks do come in
varying different lengths. So perhaps we should be
paying more attention. And today I’m going to discuss why shortening our cranks
could be important, and delve into the benefits of having that shorter
crank set on your bike. (upbeat music) Right then, lets start with the basics. The crank length is measured from the center of the pedal axle all the way through to the center of the bottom bracket spindle here. Now these come in a range of size from as little as 160 mils and can go up to as much as 185 mils. But if I’m honest, they
are mostly in a narrow band between 170 and 175 mils,
always in increments of 2.5 mil. So if we take an average of
that narrow band as 172.5 mils, sold as an average to
most bikes here in the UK, which are pitched as suitable
for a UK average height male, which would be five feet
10, or 177 centimeters, then we can deduce in
simple proportional terms that our crank length could
be 9.7% of our height. So, using this as a guide, and assuming average leg length proportion
relative to your height, we can see that crank
length should probably alter dependent on your height, and yet, referring back to
that standard 172.5 crank that I talked about, which
comes fitted as standard to effectively all bikes from as much as a 58 centimeter frame down to as little as
a 52 centimeter frame, with only something like
a 165 millimeter crank perhaps being found on
very small female bikes, we can kind of see that
the cycling industry has perhaps got stuck in the past, and effectively a lot
of us are riding cranks that are perhaps too long
for out bodies to cope with. So on the basis that our cranks could very well be a little too long, what can we expect to find as a benefit to shortening our cranks? Well first and foremost, most riders feel a general improved comfort
from a shorter crank, and as a general rule,
by shortening our cranks, there’s usually a more
powerful, smoother pedal stroke that comes from the crank and
that improved comfort too. Indeed, this is a good place to point out that the crank length
doesn’t actually have any direct impact on our power output. Unless of course you are
riding a single speed. And in that case, the crank length, or the longer the crank length, will help to generate more torque. But this is where gears come in, and they can offset any
affect that that lever length, which is our crank, will have. And I don’t really know any triathletes who are racing on a single speed bike. Indeed, the improvement in hip range is possible the biggest
advantage that shorter cranks brings to the table. The effect of crank
length is felt the most at the top of our pedal stroke,
or the 12 o’clock position when our knee’s at the tightest of angles, and therefore the knock-on effect is that the shorter the rider
or the longer the crank, the tighter our knee is
going to have to bend. So by default, the shorter the rider and the longer the crank, the less ideal a combination this is for the range of motion in our hips. More knee bend means the potential for knee pain, hip impingement, and even some lower back pain too. Plus, producing our peak
power becomes more difficult the tighter that hip angle becomes. So, the longer the crank, the
bigger the potential there is for us to have a dead
spot in our pedal stroke between 11 o’clock and two o’clock. Now a further benefit
to the shorter cranks, which a lot of triathletes
are now becoming receptive to, is the fact that we can have
some improved aerodynamics. Now this is because,
and is widely accepted by a lot of bike fitting
professionals now, that the shorter crank can allow us to get our lower torso position due to our hips being
in a more open angle, all because of those shorter cranks. Our saddle height is generally guided by the maximum leg extension we have at the bottom of our pedal stroke. So shorter cranks mean
that we’re going to have less extension by the value that we’ve shortened our cranks by. So hopefully that means you’ll understand that we need to compensate for
the shortening of our cranks by increasing our saddle
height by that same value. However, all that being said, an ideal saddle height generally falls in a sweet spot or narrow window that can be a little bit too
high or a little bit too low. Now hopefully you’ve found this sweet spot either by trial and error,
or a proper bike fit. And the chances are that
initially you wouldn’t need to alter your saddle
height because you’re in this narrow window or
sweet spot range anywyay. So a good suggestion would be to get a good few long rides in first, before you even start to think about perhaps nudging your saddle up or down by small increments of
say two to three mils. And finally, it has to be remembered that bike fitting is as much
of an art as it is a science, and doesn’t really need
to be rigidly stuck to. More guidelines to work from. So, what are the benefits to be had from having a shorter crank? Well, our pedal stroke
is going to be smoother, and therefore hopefully more efficient. They’ll also help us to
maintain a higher cadence, too. Plus, they’re going to help
us avoid that dead spot, which can be found at the
top of our pedal stroke between 11 o’clock and two o’clock. Plus, if you’re suffering any
knee, hip, or lower back pain, this could be an indicator
that your cranks are too long. So that could be a quick
fix to that problem as well. Plus, there’s little if not any evidence that taller riders are suffering injuries due to switching down
to these shorter cranks. It really just comes
down to a comfort thing or that perceived notion
I talked about earlier that a taller rider necessarily needs to have a longer crank. Now, I don’t know about you, but as someone who’s always ridden a standard 172.5 mil crank just because they’ve always
been fitted to my bikes, I for one feel pretty sold on this notion that the most logical decision is always to opt for a shorter crank. Now, if any of you have
got any experiences, or have shortened your cranks, please drop them in the comments below. I’d love to hear about that. Hopefully you’ve enjoyed this video, so please hit that thumb up like button. Don’t forget, click on
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