An observations about Q-Factor and Crank Length

Just tried a new set of cranks and I think that I've probably been
riding cranks that are a bit long, most of my life. Not really a big
deal since I don't think of myself as particularly small I was a bit
suprised.
More importantly I am much more sensitive to a large Q-Factor on long
cranks then on shorter ones. This is not a surprise if you think about
but I haven't heard anyone else make the observation before.

For the details if you ca

I grew up riding on 170mm Campy NR cranks. Still have some bikes with
the 170mm Campy NR cranks, one with 170mm Campy chorus, and my wife's
has one with 172.5 Mavic cranks. All the bikes are set up the same
way. My wife and I are almost exactly the same size. We ride each
others bikes and switch places on our tandem without adjustments. I
am 5'7.5" and about 147 lbs, normal proportions.

We both really disliked the Mavic cranks--they felt too long and much
too wide.
When I measured the Q-Factor I was shocked to discover that they were
only 1mm wider then the Chorus. (The Chorus cranks are 145mm and the
NR, 135mm). Apparently we were much more sensitive to the Q-Factor on
the longer cranks. The Chorus cranks feel wide too but tolerable.

I figured if the 172.5mm cranks felt too long, then perhaps I should
be riding something shorter the 170s. After looking at various web
sites (www.cranklength.info and Zinn's site as well as links I found
there), I decided to try 165mm cranks. My inseam is 30.5" (77.5 cm).
The 165mm cranks are 21.3% of my inseam. The Q-Factor of the new
cranks is 145mm--the same as the Chorus crank set.

The new cranks are much more comfortable. They do feel shorter but
they don't feel very wide at all. There is less stress on my right
knee with the 165mm. My right knee is temperamental due to a running
injury years ago. (I don't mean to imply that shorter cranks are
necessarily easier on the knees, but it works for me.)

I hope to borrow a friend's 172.5 Campy NR cranks with the narrower
Q-Factor and see how they feel.

(Greg Lewis) wrote in message . com...
Just tried a new set of cranks and I think that I've probably been
riding cranks that are a bit long, most of my life. Not really a big
deal since I don't think of myself as particularly small I was a bit
suprised.
More importantly I am much more sensitive to a large Q-Factor on long
cranks then on shorter ones. This is not a surprise if you think about
but I haven't heard anyone else make the observation before.

For the details if you ca

I grew up riding on 170mm Campy NR cranks. Still have some bikes with
the 170mm Campy NR cranks, one with 170mm Campy chorus, and my wife's
has one with 172.5 Mavic cranks. All the bikes are set up the same
way. My wife and I are almost exactly the same size. We ride each
others bikes and switch places on our tandem without adjustments. I
am 5'7.5" and about 147 lbs, normal proportions.

We both really disliked the Mavic cranks--they felt too long and much
too wide.
When I measured the Q-Factor I was shocked to discover that they were
only 1mm wider then the Chorus. (The Chorus cranks are 145mm and the
NR, 135mm). Apparently we were much more sensitive to the Q-Factor on
the longer cranks. The Chorus cranks feel wide too but tolerable.

I figured if the 172.5mm cranks felt too long, then perhaps I should
be riding something shorter the 170s. After looking at various web
sites (www.cranklength.info and Zinn's site as well as links I found
there), I decided to try 165mm cranks. My inseam is 30.5" (77.5 cm).
The 165mm cranks are 21.3% of my inseam. The Q-Factor of the new
cranks is 145mm--the same as the Chorus crank set.

The new cranks are much more comfortable. They do feel shorter but
they don't feel very wide at all. There is less stress on my right
knee with the 165mm. My right knee is temperamental due to a running
injury years ago. (I don't mean to imply that shorter cranks are
necessarily easier on the knees, but it works for me.)

I hope to borrow a friend's 172.5 Campy NR cranks with the narrower
Q-Factor and see how they feel.

Dear Greg,

Psychology often matters as much as physical dimensions
in how things feel to us. Double-blind testing often
shows that we're nowhere near as sensitive as we think.

If the Mavic cranks really do feel "much too wide" compared
to the Chorus cranks, but are only 1 mm wider, then it's
likely that either you're being influenced by the labels
or else aren't measuring what really affects your feet.

To illustrate how unlikely it is that either of your feet
are sensitive to a single millimeter of width, hold your
hand up in front of the computer screen, spread your thumb
and fingers, and try to hold your thumb and forefinger only
a millimeter apart. Most people will find it hard to maintain
this tiny distance without noticeable wavering.

(It's easy to cheat--brace your thumb and forefinger against
your middle finger.)

For another example, look down and try to hold the side of
your shoe a millimeter from the desk. Or put a thin envelope
between the side of your shoe and the desk--that's about a
millimeter wide. Can you feel the difference in width using
your foot?

The Mavic may be a millimeter wider than the Chorus, but
I suspect that you're probably feeling something else, even
though you write that the bikes are set up the same way.
If you're curious, you might check the seats, pedals, and
the curve and thickness of the cranks for more likely
explanations about why one feels "much too wide" when
your first measurement shows only a millimeter difference.

Carl Fogel

Psychology often matters as much as physical dimensions
in how things feel to us. Double-blind testing often
shows that we're nowhere near as sensitive as we think.

If the Mavic cranks really do feel "much too wide" compared
to the Chorus cranks, but are only 1 mm wider, then it's
likely that either you're being influenced by the labels
or else aren't measuring what really affects your feet.

To illustrate how unlikely it is that either of your feet
are sensitive to a single millimeter of width, hold your
hand up in front of the computer screen, spread your thumb
and fingers, and try to hold your thumb and forefinger only
a millimeter apart. Most people will find it hard to maintain
this tiny distance without noticeable wavering.

(It's easy to cheat--brace your thumb and forefinger against
your middle finger.)

For another example, look down and try to hold the side of
your shoe a millimeter from the desk. Or put a thin envelope
between the side of your shoe and the desk--that's about a
millimeter wide. Can you feel the difference in width using
your foot?

The Mavic may be a millimeter wider than the Chorus, but
I suspect that you're probably feeling something else, even
though you write that the bikes are set up the same way.
If you're curious, you might check the seats, pedals, and
the curve and thickness of the cranks for more likely
explanations about why one feels "much too wide" when
your first measurement shows only a millimeter difference.

Carl Fogel

People keep trying to make feelings go away by demonstrating something with
a static test. Better to demonstrate it by movement and THEN try and figure
it out.

While I agree that most of what anyone feels is in their minds, I gotta
wonder why it is that people insist that there's nothing there. Yeah, 1mm
in a static test ain't much, try rotating your feet around at 90rpm and tell
me that there's still nothing to it. In this case, not only are the
crankarms 1mm wider, but also another 2.5mm longer. I dare say that if the
arms were the same length, the OP probably wouldn't have noticed as much.
But that he did tells me that there's SOMETHING going on.

There's gotta be more to it than "its in your head, stupid," otherwise we
wouldn't keep getting these kinds of questions.

Mike
"Puzzled by the feelings"

"Mike S." mikeshaw2@coxDOTnet wrote in message news:edzWb.61049$F15.59449@fed1read06...
Psychology often matters as much as physical dimensions
in how things feel to us. Double-blind testing often
shows that we're nowhere near as sensitive as we think.

If the Mavic cranks really do feel "much too wide" compared
to the Chorus cranks, but are only 1 mm wider, then it's
likely that either you're being influenced by the labels
or else aren't measuring what really affects your feet.

To illustrate how unlikely it is that either of your feet
are sensitive to a single millimeter of width, hold your
hand up in front of the computer screen, spread your thumb
and fingers, and try to hold your thumb and forefinger only
a millimeter apart. Most people will find it hard to maintain
this tiny distance without noticeable wavering.

(It's easy to cheat--brace your thumb and forefinger against
your middle finger.)

For another example, look down and try to hold the side of
your shoe a millimeter from the desk. Or put a thin envelope
between the side of your shoe and the desk--that's about a
millimeter wide. Can you feel the difference in width using
your foot?

The Mavic may be a millimeter wider than the Chorus, but
I suspect that you're probably feeling something else, even
though you write that the bikes are set up the same way.
If you're curious, you might check the seats, pedals, and
the curve and thickness of the cranks for more likely
explanations about why one feels "much too wide" when
your first measurement shows only a millimeter difference.

Carl Fogel

People keep trying to make feelings go away by demonstrating something with
a static test. Better to demonstrate it by movement and THEN try and figure
it out.

While I agree that most of what anyone feels is in their minds, I gotta
wonder why it is that people insist that there's nothing there. Yeah, 1mm
in a static test ain't much, try rotating your feet around at 90rpm and tell
me that there's still nothing to it. In this case, not only are the
crankarms 1mm wider, but also another 2.5mm longer. I dare say that if the
arms were the same length, the OP probably wouldn't have noticed as much.
But that he did tells me that there's SOMETHING going on.

There's gotta be more to it than "its in your head, stupid," otherwise we
wouldn't keep getting these kinds of questions.

Mike
"Puzzled by the feelings"

Dear Mike,

Neither the feelings nor the questions are stupid.

But the effects are more likely either due to other
unmeasured dimension or else inside our heads.

Measure the thickness of the socks that you wear
while riding with a pair of calipers.

How much would wearing an extra pair of socks add to
the width between your feet or the distance between
your feet and your shoes?

My ordinary medium-weight socks are about 2mm thick.

That is, the single layer of extra material under the
soles of my feet lengthens my legs 2mm. Combined,
the extra pair of socks narrow the distance between
my ankles a whopping 4mm.

Does anyone believe that wearing a pair of extra socks
in cold weather requires a crank with shorter pedal
arms or a narrower spindle?

Doctors and magicians routinely use placebo effects and
misdirection to put notions in our heads. And we do it
to ourselves all the time.

If a single millimeter in actual crank width really did
feel "much too wide," then Peter Chisholm would be selling
cranks in half-millimeter widths.

A single millimeter is simply too small a distance for
us to notice while wearing shoes. It's under 1% of the
distance between our ankles while we pedal. Keep in
mind, that this means that each ankle would be only half
a millimeter farther out. Our socks and shoes flex more
than that.

U.S. shoes come in half-sizes that are about 3-5 mm apart
in length and widths A-E that vary about 5 mm:

http://www.bigfeetstuff.com/ebrannock.htm#metric

The original post's claims look like this when tabulated

length Q-factor comments
------ ------- --------
Campy NR 170.0mm 135mm grew up on these
Campy Chorus 170.0mm 145mm wide but tolerable
Mavic 172.5mm 146mm much too wide
new cranks 165.0mm 145mm much more comfortable

Frankly, it looks as length was the real problem, not
width. The rider may have been on the verge of feeling
uncomfortable with a 170mm crank, become unhappy with
a 172.5mm crank, and felt much better when he shortened
his crank to 165mm. Dropping 7.5mm in length might make
a noticeable difference--it's about 4.4%. But widening
a spindle 1 millimeter from 145mm is only about 0.7%

If so, the rider wouldn't be the first person to confuse
width and length when something felt uncomfortable. Or
to mention puzzling feelings.

That the rider and his wife can swap bikes and seats on
their tandem suggests just how insensitive we are to such
minor variations. They may be "almost exactly the same size,"
but the sexual difference alone practically guarantees
different hip widths and leg lengths for the same height.

Carl Fogel

Big Snip

I don't know about width, but I sure can tell if I've got thick or thin
socks on height-wise!

I figured it out the hard way after a few rides where I had to stop and
adjust my saddle up some for no apparent reason. Things felt strange: too
low. Next time I rode the bike with thin cycling socks on, the saddle was
too high. It took several times of this happening for me to figure out the
difference was in my socks!

Now I ride in thin socks and don't worry too much about it.

Yeah, I know I'm talking about mm here. I just happen to pay attention to
that kind of thing. Ask any of my riding friends. I'm not nearly as bad as
Eddy Merckx, but I'm persnickity about the seat position thing.

Mike

Greg Lewis wrote:


More importantly I am much more sensitive to a large Q-Factor on long
cranks then on shorter ones. This is not a surprise if you think about
but I haven't heard anyone else make the observation before.

For the details if you ca

I grew up riding on 170mm Campy NR cranks. Still have some bikes with
the 170mm Campy NR cranks, one with 170mm Campy chorus, and my wife's
has one with 172.5 Mavic cranks. All the bikes are set up the same
way. My wife and I are almost exactly the same size. We ride each
others bikes and switch places on our tandem without adjustments. I
am 5'7.5" and about 147 lbs, normal proportions.

We both really disliked the Mavic cranks--they felt too long and much
too wide.
When I measured the Q-Factor I was shocked to discover that they were
only 1mm wider then the Chorus. (The Chorus cranks are 145mm and the
NR, 135mm). Apparently we were much more sensitive to the Q-Factor on
the longer cranks. The Chorus cranks feel wide too but tolerable.

Were the pedals and shoes identical on when you switched to the Mavic
crank? The "true" Q factor might be affected greatly by pedals and shoes.

Dave
dvt at psu dot edu

I guess my original message was not at all clear, since it seems to
have been completely miss interpreted.

What I was trying to say was that longer cranks will make a too large
Q-Factor much more noticable.

My point was the Mavic's "felt" wider but weren't. So I hypothesised
that cranks shorter then I was used to would "feel" narrower, even
though
all the cranks are essentially the same width.
Which is exactly what happened.

I think 145mm width is a long way from optimal for both me and my
wife.
Which is why I think I like the NR 170s (135mm width) but not the
Chorus
170s (145mm width).

If you do a deep knee bend with your legs spread too wide you will
find
there is less strain if you bend your knees less (compared to how much
you bend at the ideal width).

If the Q-Factor is ideal for the rider, then I would not expect the
rider to be as sensitive to the crank length.

Unfortunately I couldn't find 9 speed cranks that were narrower.

"Mike S." mikeshaw2@coxDOTnet wrote in message news:ZaFWb.61347$F15.10488@fed1read06...
Big Snip

I don't know about width, but I sure can tell if I've got thick or thin
socks on height-wise!

I figured it out the hard way after a few rides where I had to stop and
adjust my saddle up some for no apparent reason. Things felt strange: too
low. Next time I rode the bike with thin cycling socks on, the saddle was
too high. It took several times of this happening for me to figure out the
difference was in my socks!

Now I ride in thin socks and don't worry too much about it.

Yeah, I know I'm talking about mm here. I just happen to pay attention to
that kind of thing. Ask any of my riding friends. I'm not nearly as bad as
Eddy Merckx, but I'm persnickity about the seat position thing.

Mike

Dear Mike,

You may have noticed that things felt somehow
different when you wore different socks, but it's
unlikely that the difference involved the height
of your seat.

We often feel slightly better when we fiddle with
things, even when it turns out that they're not
connected to anything relevant.

"There!" we say, "That's better!" And we certainly
feel better. But the bicycle with brand-new brake
cables, handlebar tape, and headset bearings is no
faster than it was before.

The wishful-thinking effect is real in that we do
indeed feel better after fiddling, but it's common
in experiments for subjects to note small but distinct
improvements after they carefully adjust dials that
are not hooked up to anything.

Unless you also adjust your seat height according
to the thickness of the shorts that you're wearing
and the wear rate of your undergarments, I suspect
that the difference was psychological--your thicker
socks felt funny, and fiddling with your seat merely
scratched an ill-defined itch.

If a mechanic had pretended to fiddle with your seat
and told you that he had raised it just a hair, you
would probably have been just as happy.

Time to defrag my hard drive. The improvement in
speed hasn't been measurable for years, but I just
know that it must be faster--after all, I feel better
afterward.

Carl Fogel

dvt wrote in message ...

Were the pedals and shoes identical on when you switched to the Mavic
crank? The "true" Q factor might be affected greatly by pedals and shoes.

Dave
dvt at psu dot edu

Same equipment, Time old style pedals, Sidi G2 shoes
Any recommondations on a narrow Q-Factor pedal?

(Greg Lewis) wrote in message . com...
dvt wrote in message ...

Were the pedals and shoes identical on when you switched to the Mavic
crank? The "true" Q factor might be affected greatly by pedals and shoes.

Dave
dvt at psu dot edu

Same equipment, Time old style pedals, Sidi G2 shoes
Any recommondations on a narrow Q-Factor pedal?

Dear Greg,

Here's a page that lists some narrower BB/crank
combinations:

http://www.wisil.recumbents.com/wisi...Crank%20Length

These people are concerned with reducing the frontal
area of recumbents rather than comfort, but they might
have what you want.

Remember, no matter what anyone says, it's how it
feels to you.

Good luck,

Carl Fogel