Crank arm length question - Page 5 - Cycling Mob: Road Cycling, Mountain Biking and More

05-19-2004, 04:52 AM

I wrote:
>>175 is pretty long. I used 172.5 with my 30 inch inseam, but went
>>down to 165 and am surprisingly happy; I expected not to like them.
On Wed, 19 May 2004 01:23:52 GMT, Chris Neary
<diabloridr@comcast.net > wrote:
>I'm not so sure about that.
>
>My Levi's are a 32 inch inseam and I run 175's on my mountain bike and
>tandem, and 172.5's on my road bike.

Mountain bikes have very different requirements for crank length. I
don't know anything about tandems.

>My wife has a 28 inch inseam and rides 165's.

Make sure you're measuring both your inseams accurately; for biking
purposes, it's not which pants are comfortable, but rather the exact
height from the floor to your crotch. One method I read somewhere is
to stand with your feet flat and your back (and legs) against a
wall, and hold a book with one edge against the wall and one edge up
to your leg joint (as high as it can), and measure from the book's
crotch edge to the floor.

Of course, having said that, I don't remember if my inseam was 30
inches when I measured that way.

>YMMV.

Agreed...In fact, that's the most important rule about crank length.
--
Rick Onanian

05-19-2004, 04:50 PM

>>My Levi's are a 32 inch inseam and I run 175's on my mountain bike and
>>tandem, and 172.5's on my road bike.
>
>Mountain bikes have very different requirements for crank length. I
>don't know anything about tandems.

Mountain bikes, tandems, and time trial bikes tend to have slightly longer
cranks since cadence on these bikes is usually lower but torque is somewhat
higher.

Fixed gear bikes, OTOH, tend to run shorter cranks for the opposite reason,
as well to avoid pedal strikes in some instances. My fixie has 170mm cranks.

>>My wife has a 28 inch inseam and rides 165's.
>
>Make sure you're measuring both your inseams accurately; for biking
>purposes, it's not which pants are comfortable, but rather the exact
>height from the floor to your crotch. One method I read somewhere is
>to stand with your feet flat and your back (and legs) against a
>wall, and hold a book with one edge against the wall and one edge up
>to your leg joint (as high as it can), and measure from the book's
>crotch edge to the floor.
>
>Of course, having said that, I don't remember if my inseam was 30
>inches when I measured that way.

I answered the question as I did since the original poster only supplied his
pants inseam. What size pants do you wear?

Chris Neary
[Only registered and activated users can see links. ]

"Science, freedom, beauty, adventure: what more could
you ask of life? Bicycling combined all the elements I
loved" - Adapted from a quotation by Charles Lindbergh

05-19-2004, 04:50 PM

>>My Levi's are a 32 inch inseam and I run 175's on my mountain bike and
>>tandem, and 172.5's on my road bike.
>
>Mountain bikes have very different requirements for crank length. I
>don't know anything about tandems.

Mountain bikes, tandems, and time trial bikes tend to have slightly longer
cranks since cadence on these bikes is usually lower but torque is somewhat
higher.

Fixed gear bikes, OTOH, tend to run shorter cranks for the opposite reason,
as well to avoid pedal strikes in some instances. My fixie has 170mm cranks.

>>My wife has a 28 inch inseam and rides 165's.
>
>Make sure you're measuring both your inseams accurately; for biking
>purposes, it's not which pants are comfortable, but rather the exact
>height from the floor to your crotch. One method I read somewhere is
>to stand with your feet flat and your back (and legs) against a
>wall, and hold a book with one edge against the wall and one edge up
>to your leg joint (as high as it can), and measure from the book's
>crotch edge to the floor.
>
>Of course, having said that, I don't remember if my inseam was 30
>inches when I measured that way.

I answered the question as I did since the original poster only supplied his
pants inseam. What size pants do you wear?

Chris Neary
[Only registered and activated users can see links. ]

"Science, freedom, beauty, adventure: what more could
you ask of life? Bicycling combined all the elements I
loved" - Adapted from a quotation by Charles Lindbergh

05-19-2004, 04:50 PM

>>My Levi's are a 32 inch inseam and I run 175's on my mountain bike and
>>tandem, and 172.5's on my road bike.
>
>Mountain bikes have very different requirements for crank length. I
>don't know anything about tandems.

Mountain bikes, tandems, and time trial bikes tend to have slightly longer
cranks since cadence on these bikes is usually lower but torque is somewhat
higher.

Fixed gear bikes, OTOH, tend to run shorter cranks for the opposite reason,
as well to avoid pedal strikes in some instances. My fixie has 170mm cranks.

>>My wife has a 28 inch inseam and rides 165's.
>
>Make sure you're measuring both your inseams accurately; for biking
>purposes, it's not which pants are comfortable, but rather the exact
>height from the floor to your crotch. One method I read somewhere is
>to stand with your feet flat and your back (and legs) against a
>wall, and hold a book with one edge against the wall and one edge up
>to your leg joint (as high as it can), and measure from the book's
>crotch edge to the floor.
>
>Of course, having said that, I don't remember if my inseam was 30
>inches when I measured that way.

I answered the question as I did since the original poster only supplied his
pants inseam. What size pants do you wear?

Chris Neary
[Only registered and activated users can see links. ]

"Science, freedom, beauty, adventure: what more could
you ask of life? Bicycling combined all the elements I
loved" - Adapted from a quotation by Charles Lindbergh

05-19-2004, 04:50 PM

>>My Levi's are a 32 inch inseam and I run 175's on my mountain bike and
>>tandem, and 172.5's on my road bike.
>
>Mountain bikes have very different requirements for crank length. I
>don't know anything about tandems.

Mountain bikes, tandems, and time trial bikes tend to have slightly longer
cranks since cadence on these bikes is usually lower but torque is somewhat
higher.

Fixed gear bikes, OTOH, tend to run shorter cranks for the opposite reason,
as well to avoid pedal strikes in some instances. My fixie has 170mm cranks.

>>My wife has a 28 inch inseam and rides 165's.
>
>Make sure you're measuring both your inseams accurately; for biking
>purposes, it's not which pants are comfortable, but rather the exact
>height from the floor to your crotch. One method I read somewhere is
>to stand with your feet flat and your back (and legs) against a
>wall, and hold a book with one edge against the wall and one edge up
>to your leg joint (as high as it can), and measure from the book's
>crotch edge to the floor.
>
>Of course, having said that, I don't remember if my inseam was 30
>inches when I measured that way.

I answered the question as I did since the original poster only supplied his
pants inseam. What size pants do you wear?

Chris Neary
[Only registered and activated users can see links. ]

"Science, freedom, beauty, adventure: what more could
you ask of life? Bicycling combined all the elements I
loved" - Adapted from a quotation by Charles Lindbergh

05-19-2004, 04:50 PM

>>My Levi's are a 32 inch inseam and I run 175's on my mountain bike and
>>tandem, and 172.5's on my road bike.
>
>Mountain bikes have very different requirements for crank length. I
>don't know anything about tandems.

Mountain bikes, tandems, and time trial bikes tend to have slightly longer
cranks since cadence on these bikes is usually lower but torque is somewhat
higher.

Fixed gear bikes, OTOH, tend to run shorter cranks for the opposite reason,
as well to avoid pedal strikes in some instances. My fixie has 170mm cranks.

>>My wife has a 28 inch inseam and rides 165's.
>
>Make sure you're measuring both your inseams accurately; for biking
>purposes, it's not which pants are comfortable, but rather the exact
>height from the floor to your crotch. One method I read somewhere is
>to stand with your feet flat and your back (and legs) against a
>wall, and hold a book with one edge against the wall and one edge up
>to your leg joint (as high as it can), and measure from the book's
>crotch edge to the floor.
>
>Of course, having said that, I don't remember if my inseam was 30
>inches when I measured that way.

I answered the question as I did since the original poster only supplied his
pants inseam. What size pants do you wear?

Chris Neary
[Only registered and activated users can see links. ]

"Science, freedom, beauty, adventure: what more could
you ask of life? Bicycling combined all the elements I
loved" - Adapted from a quotation by Charles Lindbergh

05-19-2004, 06:14 PM

In article <[Only registered and activated users can see links. ]>,
Chris Neary <[Only registered and activated users can see links. ] > wrote:

> >>My Levi's are a 32 inch inseam and I run 175's on my mountain bike and
> >>tandem, and 172.5's on my road bike.
> >
> >Mountain bikes have very different requirements for crank length. I
> >don't know anything about tandems.
>
> Mountain bikes, tandems, and time trial bikes tend to have slightly longer
> cranks since cadence on these bikes is usually lower but torque is somewhat
> higher.

Why do mountain bikes run long cranks? Torque can be adjusted with lower
gearing to make the gain ratio <http://www.sheldonbrown.com/gain.html>
come out the same, and pedal strikes are a huge problem for mountain
bikes even on straight stretches.

I intend to put this theory to the test as soon as I find some 165 mm
cranks that fit within my budget.

--
Ryan Cousineau, [Only registered and activated users can see links. ] [Only registered and activated users can see links. ]
President, Fabrizio Mazzoleni Fan Club

05-19-2004, 06:14 PM

In article <[Only registered and activated users can see links. ]>,
Chris Neary <[Only registered and activated users can see links. ] > wrote:

> >>My Levi's are a 32 inch inseam and I run 175's on my mountain bike and
> >>tandem, and 172.5's on my road bike.
> >
> >Mountain bikes have very different requirements for crank length. I
> >don't know anything about tandems.
>
> Mountain bikes, tandems, and time trial bikes tend to have slightly longer
> cranks since cadence on these bikes is usually lower but torque is somewhat
> higher.

Why do mountain bikes run long cranks? Torque can be adjusted with lower
gearing to make the gain ratio <http://www.sheldonbrown.com/gain.html>
come out the same, and pedal strikes are a huge problem for mountain
bikes even on straight stretches.

I intend to put this theory to the test as soon as I find some 165 mm
cranks that fit within my budget.

--
Ryan Cousineau, [Only registered and activated users can see links. ] [Only registered and activated users can see links. ]
President, Fabrizio Mazzoleni Fan Club

05-19-2004, 06:14 PM

In article <[Only registered and activated users can see links. ]>,
Chris Neary <[Only registered and activated users can see links. ] > wrote:

> >>My Levi's are a 32 inch inseam and I run 175's on my mountain bike and
> >>tandem, and 172.5's on my road bike.
> >
> >Mountain bikes have very different requirements for crank length. I
> >don't know anything about tandems.
>
> Mountain bikes, tandems, and time trial bikes tend to have slightly longer
> cranks since cadence on these bikes is usually lower but torque is somewhat
> higher.

Why do mountain bikes run long cranks? Torque can be adjusted with lower
gearing to make the gain ratio <http://www.sheldonbrown.com/gain.html>
come out the same, and pedal strikes are a huge problem for mountain
bikes even on straight stretches.

I intend to put this theory to the test as soon as I find some 165 mm
cranks that fit within my budget.

--
Ryan Cousineau, [Only registered and activated users can see links. ] [Only registered and activated users can see links. ]
President, Fabrizio Mazzoleni Fan Club

05-19-2004, 06:14 PM

In article <[Only registered and activated users can see links. ]>,
Chris Neary <[Only registered and activated users can see links. ] > wrote:

> >>My Levi's are a 32 inch inseam and I run 175's on my mountain bike and
> >>tandem, and 172.5's on my road bike.
> >
> >Mountain bikes have very different requirements for crank length. I
> >don't know anything about tandems.
>
> Mountain bikes, tandems, and time trial bikes tend to have slightly longer
> cranks since cadence on these bikes is usually lower but torque is somewhat
> higher.

Why do mountain bikes run long cranks? Torque can be adjusted with lower
gearing to make the gain ratio <http://www.sheldonbrown.com/gain.html>
come out the same, and pedal strikes are a huge problem for mountain
bikes even on straight stretches.

I intend to put this theory to the test as soon as I find some 165 mm
cranks that fit within my budget.

--
Ryan Cousineau, [Only registered and activated users can see links. ] [Only registered and activated users can see links. ]
President, Fabrizio Mazzoleni Fan Club