Refining choice for a shorter crank. Crank length selection and seat position.

thirty-six wrote:
On Jul 26, 3:38 am, "Steve Freides" wrote:
thirty-six wrote:

I'm trying to sort out that formula to help others.


You've answered this one already by yourself - you know what works
for you, so use it.

First of all, I don't know what works best or with least effort per
mile. It could well be that a 5" or 6" long crank be best. Does the
way I've assessed for correct length stand up to scrutiny and so used
for others or is there a damning reason to go shorter still? I do
understand the claim for an aerodynamic pursuiters position being
benefitted by shorter cranks to assist in breathing and reduce
aerodynamic drag. That's not a particular requirement for me. A 5"
crank would also require a frame change, so the evidence would have to
be strong to get me to that size. I suspect that I should be able to
use 100mm in saddle length which would indicate that the cranks need
to be around 50mm shorter than they are (just because I'm so
restricted with them). But this would suggest 120mm cranks. Even a
5" (127mm) crank sounds too small, but I've been conditioned to 165 to
175 as the norm.

There is no "perfect" to be had here. As engineers say, everything is a
compromise. You have to pick you priorities.

As but one example, I'm sure a lot of pro's hate their TT position but,
as long as it doesn't get them injured, that's just tough luck for them
because performance comes before everything else when you're getting
paid for your performance.

Don't forget, either, that track bikes (your example of pursuiters) are
fixed gears and, as such, crank length has at least a somewhat different
meaning. I can tell you from personal experience that when I was
recovering from a serious back injury about 15 years ago, I could ride a
fixed gear but I couldn't ride a normal bike - mind you, I have no idea
if this is significant in the grand scheme of things but I can tell you
that things are different when you're on a track, and even when you're
on track-style equipment like a fixed gear on the road.

If I could sum up my advice to you in a word, it would be "relax" - your
quest to improve has to start with being able to perform safely and,
especially since, I assume, you're not doing this for a living, anything
that causes you back pain after a ride is simply an unacceptable
compromise, even if it helped you be faster. OTOH, if you find you
prefer to race criteriums with a different size of crank than you use
for long road races because it makes you go faster at those shorter
distances, well, that would be an example of an OK compromise in my
book. Just don't forget that there are tradeoffs in any choice of
equipment and it is not - I repeat _not_ - an exact science.

-S-

I think most fitters seek out a position that is is more dependent on
the riders current flexibility and strength than actual anatomical
limitations. Its a compromise of comfort and power, often in a single
session, so there's little incentive to prescribe strength and
flexibility exercises and evolve a position that is more aero, or uses
a longer crank for hills, for example.

I do like a local physio who is a former high performance rider and
does fittings. She looks more at strength and flexibility of the
individual than the knee over pedal type rules of thumb. Still, it's
kinda one shot deal, vs a plan to work towards an ideal.

On Jul 26, 5:10*pm, "Steve Freides" wrote:
thirty-six wrote:
On Jul 26, 3:38 am, "Steve Freides" wrote:
thirty-six wrote:

I'm trying to sort out that formula to help others.

You've answered this one already by yourself - you know what works
for you, so use it.

First of all, I don't know what works best or with least effort per
mile. *It could well be that a 5" or 6" long crank be best. *Does the
way I've assessed for correct length stand up to scrutiny and so used
for others or is there a damning reason to go shorter still? *I do
understand the claim for an aerodynamic pursuiters position being
benefitted by shorter cranks to assist in breathing and reduce
aerodynamic drag. *That's not a particular requirement for me. *A 5"
crank would also require a frame change, so the evidence would have to
be strong to get me to that size. *I suspect that I should be able to
use 100mm in saddle length which would indicate that the cranks need
to be around 50mm shorter than they are (just because I'm so
restricted with them). *But this would suggest 120mm cranks. *Even a
5" (127mm) crank sounds too small, but I've been conditioned to 165 to
175 as the norm.

There is no "perfect" to be had here. *As engineers say, everything is a
compromise. *You have to pick you priorities.

As but one example, I'm sure a lot of pro's hate their TT position but,
as long as it doesn't get them injured, that's just tough luck for them
because performance comes before everything else when you're getting
paid for your performance.

Don't forget, either, that track bikes (your example of pursuiters) are
fixed gears and, as such, crank length has at least a somewhat different
meaning. *I can tell you from personal experience that when I was
recovering from a serious back injury about 15 years ago, I could ride a
fixed gear but I couldn't ride a normal bike - mind you, I have no idea
if this is significant in the grand scheme of things but I can tell you
that things are different when you're on a track, and even when you're
on track-style equipment like a fixed gear on the road.

If I could sum up my advice to you in a word, it would be "relax" - your
quest to improve has to start with being able to perform safely and,
especially since, I assume, you're not doing this for a living, anything
that causes you back pain after a ride is simply an unacceptable
compromise, even if it helped you be faster. *OTOH, if you find you
prefer to race criteriums with a different size of crank than you use
for long road races because it makes you go faster at those shorter
distances, well, that would be an example of an OK compromise in my
book. *Just don't forget that there are tradeoffs in any choice of
equipment and it is not - I repeat _not_ - an exact science.

-S-

This is all very interesting but I am not competetively active nor am
I likely to be. Yes, I'd prefer to go out for six hours on the bike
and get home and not have to worry about having to have a soak,
massage and bed rest to help recouperate. If I think objectively it
means I should look for the shortest available cranks off the shelf
with 9/16" pedal fitting, at a low price... and see what happens.

Supposedly I'll need smaller gears. Hmm, my ex-racing bike is
slightly undergeared as it is, but I doubt that a135mm BCD crankset
exists in the sort of length I am looking for (closer to 120mm than
170mm).

I'm too tired now to think much further at the minute but have been
considering how the rotation of position as a rider moves into the
hooks should move him forward on the saddle. It seems I could have
used bars with a greater reach and drop than I did. I favoured the
tight bends because my hands were secure over rough tracks, and race
circuits are not necessarily on the best roads.

On Jul 26, 3:26*pm, thirty-six wrote:
On Jul 26, 5:10*pm, "Steve Freides" wrote:





thirty-six wrote:
On Jul 26, 3:38 am, "Steve Freides" wrote:
thirty-six wrote:

I'm trying to sort out that formula to help others.

You've answered this one already by yourself - you know what works
for you, so use it.

First of all, I don't know what works best or with least effort per
mile. *It could well be that a 5" or 6" long crank be best. *Does the
way I've assessed for correct length stand up to scrutiny and so used
for others or is there a damning reason to go shorter still? *I do
understand the claim for an aerodynamic pursuiters position being
benefitted by shorter cranks to assist in breathing and reduce
aerodynamic drag. *That's not a particular requirement for me. *A 5"
crank would also require a frame change, so the evidence would have to
be strong to get me to that size. *I suspect that I should be able to
use 100mm in saddle length which would indicate that the cranks need
to be around 50mm shorter than they are (just because I'm so
restricted with them). *But this would suggest 120mm cranks. *Even a
5" (127mm) crank sounds too small, but I've been conditioned to 165 to
175 as the norm.

There is no "perfect" to be had here. *As engineers say, everything is a
compromise. *You have to pick you priorities.

As but one example, I'm sure a lot of pro's hate their TT position but,
as long as it doesn't get them injured, that's just tough luck for them
because performance comes before everything else when you're getting
paid for your performance.

Don't forget, either, that track bikes (your example of pursuiters) are
fixed gears and, as such, crank length has at least a somewhat different
meaning. *I can tell you from personal experience that when I was
recovering from a serious back injury about 15 years ago, I could ride a
fixed gear but I couldn't ride a normal bike - mind you, I have no idea
if this is significant in the grand scheme of things but I can tell you
that things are different when you're on a track, and even when you're
on track-style equipment like a fixed gear on the road.

If I could sum up my advice to you in a word, it would be "relax" - your
quest to improve has to start with being able to perform safely and,
especially since, I assume, you're not doing this for a living, anything
that causes you back pain after a ride is simply an unacceptable
compromise, even if it helped you be faster. *OTOH, if you find you
prefer to race criteriums with a different size of crank than you use
for long road races because it makes you go faster at those shorter
distances, well, that would be an example of an OK compromise in my
book. *Just don't forget that there are tradeoffs in any choice of
equipment and it is not - I repeat _not_ - an exact science.

-S-

This is all very interesting but I am not competetively active nor am
I likely to be. *Yes, I'd prefer to go out for six hours on the bike
and get home and not have to worry about having to have a soak,
massage and bed rest to help recouperate. *If I think objectively it
means I should look for the shortest available cranks off the shelf
with 9/16" pedal fitting, at a low price... *and see what happens.

Supposedly I'll need smaller gears. *Hmm, my ex-racing bike is
slightly undergeared as it is, but I doubt that a135mm BCD crankset
exists in the sort of length I am looking for (closer to 120mm than
170mm).

I'm too tired now to think much further at the minute but have been
considering how the rotation of position as a rider moves into the
hooks should move him forward on the saddle. * It seems I could have
used bars with a greater reach and drop than I did. I favoured the
tight bends because my hands were secure over rough tracks, and race
circuits are not necessarily on the best roads.

Go for the comfort and ergonomics ("protection from injury/
discomfort"). Try the 165's on a bike that otherwise suits you and see
what happens. Worked for me.
--D-y

wrote:

Go for the comfort and ergonomics ("protection from injury/
discomfort"). Try the 165's on a bike that otherwise suits you and see
what happens. Worked for me.
--D-y

+1 - based on everything you've said, it sounds like you'll be happy
with 165's.

I wouldn't change your gearing at all - you can always do that later if
you need, but the difference isn't that dramatic that you have to run
out and buy a new drivetrain.

-S-

mtb Dad wrote:
I think most fitters seek out a position that is is more dependent on
the riders current flexibility and strength than actual anatomical
limitations. Its a compromise of comfort and power, often in a single
session, so there's little incentive to prescribe strength and
flexibility exercises and evolve a position that is more aero, or uses
a longer crank for hills, for example.

I do like a local physio who is a former high performance rider and
does fittings. She looks more at strength and flexibility of the
individual than the knee over pedal type rules of thumb. Still, it's
kinda one shot deal, vs a plan to work towards an ideal.

Yes, I agree - the better the fitter can look at the person getting
fitted in all their aspects, the better the results will be, e.g., if
someone comes in who's obviously athletic, looks like they're open to
advice, and has tight hamstrings, then the best thing might be to
suggest working on the hamstrings for a while before having a fit kit
done.

I'm showing my exercise prejudice here, but the kettlebell swing and
barbell deadlift both have potential to solve tight hamstrings and
improve strength as well. I used to always have to lower my saddle
every Spring because I'd lost some of my cycle-specific flexibility over
the winter, but once I started doing kettlebell swings regularly, that
problem went away and has never come back.

Disclaimer: I'm an instructor (actually, an instructor's instructor) in
the RKC program, see here

http://www.dragondoor.com/steve-freides/?apid=1022

The picture should let you know I don't have hamstring flexibility
problems.

-S-

On 7/26/2011 3:26 PM, thirty-six wrote:
[...]
Supposedly I'll need smaller gears. Hmm, my ex-racing bike is
slightly undergeared as it is, but I doubt that a135mm BCD crankset
exists in the sort of length I am looking for (closer to 120mm than
170mm).[...]

If you want cranks that short, here is the place:
http://bikesmithdesign.com/Short_Cranks/index.html.

Sheldon Brown's Gain Ratio calculator can assist in helping you decide
what size chainwheels you want with different crank lengths:
http://sheldonbrown.com/gears/.

--
Tºm Shermªn - 42.435731°N, 83.985007°W
I am a vehicular cyclist.

On Jul 27, 9:41*pm, "Steve Freides" wrote:
wrote:
Go for the comfort and ergonomics ("protection from injury/
discomfort"). Try the 165's on a bike that otherwise suits you and see
what happens. Worked for me.
--D-y

+1 - based on everything you've said, it sounds like you'll be happy
with 165's.

I wouldn't change your gearing at all - you can always do that later if
you need, but the difference isn't that dramatic that you have to run
out and buy a new drivetrain.

-S-

On my second bike (same size, softer stays) I have 165s, I'm thinking
that with smaller crank again I will resort to a wind-cheating
position more frequently without fear of incurring hamstring strain
leading to back pain. From what I can make out there is little I can
lose out on. It's a little further to get up and down from but the
payoff is greater lean angles (at least in the dry) and more capable
off-road use.
I fully understand the requirement to do hamstring stretches for a
racing position with the typical length cranks, but I usually want to
just jump on the bike and go, exactly like when I was 16.

thirty-six wrote:
On Jul 27, 9:41 pm, "Steve Freides" wrote:
wrote:
Go for the comfort and ergonomics ("protection from injury/
discomfort"). Try the 165's on a bike that otherwise suits you and
see what happens. Worked for me.
--D-y

+1 - based on everything you've said, it sounds like you'll be happy
with 165's.

I wouldn't change your gearing at all - you can always do that later
if you need, but the difference isn't that dramatic that you have to
run out and buy a new drivetrain.

-S-

On my second bike (same size, softer stays) I have 165s, I'm thinking
that with smaller crank again I will resort to a wind-cheating
position more frequently without fear of incurring hamstring strain
leading to back pain. From what I can make out there is little I can
lose out on. It's a little further to get up and down from but the
payoff is greater lean angles (at least in the dry) and more capable
off-road use.
I fully understand the requirement to do hamstring stretches for a
racing position with the typical length cranks, but I usually want to
just jump on the bike and go, exactly like when I was 16.

"... exactly like when I was 16." Well, that's a conversation starter,
for sure. There are a lot of things that you just can't do exactly like
when you were 16. According to my wife, some of those changes are for
the better. But you must realize that as you get older, retaining
the _functionality_ you had when you were younger requires _work_. If
you aren't willing to do the work, you will have to accept the reduced
functionality.

No one is telling you to do a half-hour yoga routine every time before
you ride, but if 30 seconds of toe touches help, then that seems to me
to be a more than worthwhile tradeoff. And here's another good thing to
think about - if you do the stretching _most_ of the time, you can get
away with missing it once in a while. Our bodies remember what we're
able to do and not do very well, and you'll still have the hamstring
flexibility, or at least most of it, on those times you skip the
stretches.

Me, I'd be happy to ride fast enough that cheating the wind made a lot
of difference.

-S-

On Jul 29, 6:52*am, thirty-six wrote:
On Jul 27, 9:41*pm, "Steve Freides" wrote:

wrote:
Go for the comfort and ergonomics ("protection from injury/
discomfort"). Try the 165's on a bike that otherwise suits you and see
what happens. Worked for me.
--D-y

+1 - based on everything you've said, it sounds like you'll be happy
with 165's.

I wouldn't change your gearing at all - you can always do that later if
you need, but the difference isn't that dramatic that you have to run
out and buy a new drivetrain.

-S-

On my second bike (same size, softer stays) I have 165s, I'm thinking
that with *smaller crank again I will resort to a wind-cheating
position more frequently without fear of incurring hamstring strain
leading to back pain. *From what I can make out there is little I can
lose out on. *It's a little further to get up and down from but the
payoff is greater lean angles (at least in the dry) and more capable
off-road use.
* I fully understand the requirement to do hamstring stretches for a
racing position with the typical length cranks, but I usually want to
just jump on the bike and go, exactly like when I was 16.

Don't know if this has been talked about, but this is the great
discovery of triathletes. By having 78 degree angles on their bikes,
they can get really low and the angle between their lower backs and
the hamstring is not as steep.

I used to get back pain after riding about 40 miles and would have to
get off my bike and stretch. I had a custom built ti frame made in
china for peanuts with a 76 degree angle. Now, I can ride aero non-
stop for miles on end without getting a tight lower back. I usually
ride around 50 miles, non-stop every sat and sunday. No back problems
to report. It was a huge difference for my short femurs to get a 170
crankset and a 76 degree angle. I do have a 73.5 angle bike. But, but,
but....I have the longest saddle possible, fairly forward, and I tend
to sit up front. Also, no problems with my lower back.

I noticed that most of my buddies ride on the brake hoods. I ride on
the drops all the time. I believe that most people would be much more
comfortable on 76 to 78 degree angled bikes. But, since 23 year old,
ultra fit, pros, who ride a million miles a day ride 73 degree angles,
all bikes are designed like that. When you buy a bike from a local
bike shop, they fit you as if you were Lance Armstrong.