crank length is a very important part of bike fitting which is often overlooked in
hindsight i was probably running the wrong length crank for many years and if you do
ride the wrong crank length it can have big ramifications in terms of your comfort on
the bike and therefore your performance in today's episode we're gonna cover everything
to do with crank length that you might need to know mine's longer than yours
so the crank is the arm that the pedal fixes to uh it comes in a multitude of different lengths
it's available from the big three shimano rit cam pack and sram as well as some of the market jobs
like this crowder more on that in a bit typically speaking you they'll start at 165 millimeters go
up to 170 172 and a half 175 and that's kind of where they top out the the kind
of commercially available cranks typically come from 165 to 175. that measurement is taken from
center of the spindle sent to the bottom bracket axle right the way to the middle of where the
pedal joins i've damaged this crank that's right it's only cheap one the crank length
that the bike comes with is probably a pretty good starting point because the crank length
on an off-the-shelf bike scales with the size of the bike i think that that scale is slightly
disjointed in that you're still seeing 52 54 centimeter bites with a 172 and a half millimeter
crank which in my experience is probably a little bit on the long side i feel those sizes probably
ought to be running 170 which is definitely the best selling crank that i tend to sell
so if you think that the average height of you know average height man is like five foot nine
170 more crank is definitely the my best selling crank 165 for women is probably our best-selling
crank as well actually the optimal crank length for an individual is dictated by the
functionality of that individual so if you've got and this is where a lot of the studies that you'll
read about crank length and the optimum crankling will fall flat in the face because they're carried
out on an elite athlete very very functional got high levels of mobility high levels of strength
high levels of flexibility they're then using that data to sell to consumers who typically lead much
more sedentary lifestyles they're less functional carrying a few extra pounds as a result of sitting
down or standing up for a reason for a long amount of time hips tend to get a little bit tighter so
frankly there is a trend for going short of being better but it isn't always better if
the length of your crank scales with the size of your bike does that basically mean it also scales
with rider height absolutely i think that the the the bigger problems actually lie in the extremes
so if you've got someone who is kind of like below five foot two 165 millimeter crack is two is too
long and at the opposite end if you've got an individual who's got like i've had guys recently
we've had like one meter in seams about 175 miles just too short for them typically not always but
the bigger the bike the longer the side the bigger the bike the bigger the rider the longer the crank
if the crank is too long what is resulting in is hip closure so it's going to you're
going to struggle to get over the top of the pedal stroke and we found the even a reduction
as little as two and a half millimeters can have quite profound differences in improving a ride's
pedaling dynamics can impact saddle interaction which frankly can have uh uh an effect on the
rest of the on the rest of the position if you have a really really excessive crank length if
you've got a very small person running a 175 millimeter you could end up with a situation
where you've got quite a lot of load of flexion going through the knee so it could put quite a
lot of stress on the knee joint i mean i have had that recently where i've had an individual who is
like you know five foot six five foot seven riding 175 mil crank and that was causing big problems
but it's relatively uncommon you do tend to see it on very very budget bikes where you've got
um you know a 54 centimeter bike or you know kind of medium-sized bike it's got 175 millimeter crank
that's a bit of an alarm bell what you're kind of looking for is a an extra small to small
should probably have a 165 millimeter on it a small to medium probably able to have a 170 or 172
a large to extra large is going to have 175 millimeter if you've got something
that is not kind of falling within that range something's probably a miss
if your crank length is too short what i've come to find and i've found this through
experimentation through comparative testing because we have an adjustable crank on our
jig that uh enables us to actually test it in a controlled environment it typically results
in the rider kind of spilling over the crank falling into the front of the bike so although
it doesn't necessarily have a negative impact on pedaling dynamics it can have an impact on
by handling and i think one of the kind of myths i wanted to dispel with this video is that shorter
is not always better we've got you know if you've got an individual who's like six foot six right
165 millimeter crank i would be very surprised if that was optimal i sell a reasonable amount
of 180 millimeter cranks i sell a lot of 150 to 155 millimeter cranks i tend to see a lot more
smaller people when you're talking extremes of the the spectrum i see a lot more short short people
than i do very very tall people there's been quite a lot of talk about shorter always being
better because it opens up the hips now the thing is there are other ways of opening up the hips you
can reduce the stack of the pedal by using certain pedal systems you can use a thinner a thinner
sole in the shoe you can increase the stars you can reduce the saddle setback there are lots of
ways of improving hip function without simply just reducing the crank uh like i said i feel that when
you go too short you start to lose the leverage element of it and i come to find that you sort of
spill over the front of it in front of the bike which means it has adverse effects on handling
i mean yeah absolutely one of the benefits of reducing crank length is that you keep
the the terminal extension of the leg the same at the bottom
but the hip angle closure at the top of the stroke is reduced so it basically improves your
ability to come through the top of the stroke but ultimately yes if you're reducing your crank
length by five millimeters you probably want to raise the saddle height by five millimeters
if someone's saying to you you should be riding a
shorter crank but they don't have the means of testing it
why you know you've got to be able to test it so you know ways of testing would be to either very
expensively buy lots of different cranks there are some cranks out there that are actually adjustable
i think that looks zed crank for example which i don't think they even make anymore has some
adjustability i can't remember there's another there's another brand that makes an adjustable
crank uh but we we adjust crank like every bike fit uh just because we can not not it's not about
selling cranks it's just about understanding what's right for an individual and that's why we
don't we don't just sell 170s we don't just sell 170s we sell you know a plethora of options and
that's why we carry options from 150 millimeters all the way up to 180 millimeters i'm actually in
the process of of having some cranks made because you know you can't you can't get for example you
can't get 180 millimeter cranks easily i recently had a guy who had to buy a dura ace power meter
because it was the only 180 millimeter crank i could find yeah poor guy um but but it's true you
know there are there aren't enough options shimano is definitely going in the right direction so for
uh 105 ultegra and even dura ace you can now get 160 millimeter crank thank you shimano uh cam pack
but don't do anything less than a 170 they did at 165. so you want it shorter that's what you're
looking for really i want more options i don't necessarily want shorter i just want there to be
more options for people and i think going so people think 155 millimeters or 150 millimeters
is kooky it's not if you've got someone who is you know outside of the realms of the you know
the kind of bell curve of averages if you've got someone who is don't even have to be that sure
five foot three five foot four 165 millimeter crack almost always is too long this is the
thing it's all about the specific needs of an individual you can't generalize with this stuff
that marks the end of today's video thank you so much for watching if you have any questions
please put in the comment section down below and i'm sure james will do his best to answer them
equally if you'd like to book a fit with him it's based in richmond in london and
you can do that through the website which i'll also link down below