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maximum weight on a Bianchi Eros frame.



 
 
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  #11  
Old July 21st 05, 02:18 AM
Chalo
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Default maximum weight on a Bianchi Eros frame.

Llatikcuf wrote:
If you refer to the simple geometric principle that volume is
proportional to height^3, then you'll see that 6'8" and 300 lbs is
equivalent to 6'0" and 219 lbs., or 5'6" and 168 lbs. That's normal
for fit men of heavy build at those heights.


that's not how I remember health class-

http://www.intmed.mcw.edu/clincalc/body.html

6' 8" 300# = BMI of 33
6' 0" 219# = BMI of 29.7
5' 6" 168# = BMI of 27.1

Not equivalent in my book

Equivalent would be:

6' 0" 243# BMI of 33
5' 6" 205# BMI of 33

Just an observation.


BMI is intrinsically flawed because it is geometrically erroneous.
What BMI purports to say is that a 1x1x1 cube is "underweight", a 2x2x2
cube is "normal", and a 3x3x3 cube is "morbidly obese". That's
ridiculous right on its face.

Chalo Colina

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  #12  
Old July 21st 05, 02:32 AM
Llatikcuf
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Default maximum weight on a Bianchi Eros frame.



Chalo wrote:

BMI is intrinsically flawed because it is geometrically erroneous.
What BMI purports to say is that a 1x1x1 cube is "underweight", a 2x2x2
cube is "normal", and a 3x3x3 cube is "morbidly obese". That's
ridiculous right on its face.

Chalo Colina


Ok, sounds good.

  #13  
Old July 21st 05, 01:33 PM
Qui si parla Campagnolo
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Default maximum weight on a Bianchi Eros frame.



Chalo wrote:
Qui si parla Campagnolo wrote:

Chalo wrote:


Do switch to some kind of tubular spindle crank if your bike is
equipped with a square taper, though. When those things snap off-- and
that is the only way they fail structurally-- you can get seriously
hurt. One of the new 2-piece cranks with outboard-mounted BB bearings
would be a good choice.


Maybe you ought to see how much the gent weighs before you assume that
a square taper crank/BB will be unsafe. Many have ridden square taper
w/o problem for decades, and to paint it as 'unsafe' for nearly anybody
is not accurate.


As I've told you before, I have broken two square tapers under pedaling
loads alone; one when I weighed about 240 lbs., and the other when I
weighed about 260 lbs.

IMO this is not so far out of the normal range that the square taper
can be considered safe. The OP does consider himself enough heavier
than average to pose the question.


And as I have mentioned, there is something amiss in the ones you used
and I do not think it's a design flaw. Many as heavy and strong as you
or more so, have used square taper for decades w/o any failures.

In 20 years I have seen 3 BB square tapers break. I have also seen 2
octalink break and we will have to see about the two piece systems, as
they have only been around for 3 years so far.


That's not terribly surprising about Octalink (it being a Shimano
product after all), but I did assume that the feeble little crankarm
splines would strip before the "pipe spindle" snapped.

Chalo Colina


  #14  
Old July 21st 05, 02:25 PM
David Damerell
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Default maximum weight on a Bianchi Eros frame.

Quoting Llatikcuf :
If you refer to the simple geometric principle that volume is
proportional to height^3, then you'll see that 6'8" and 300 lbs is
equivalent to 6'0" and 219 lbs., or 5'6" and 168 lbs. That's normal
for fit men of heavy build at those heights.

that's not how I remember health class-

[BMI]

Indeed, it is obvious that BMI is bogus for people of unusual height
precisely because it does not take account of the square-cube law.
--
David Damerell Distortion Field!
Today is First Mania, July.
  #15  
Old July 21st 05, 03:58 PM
41
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Default maximum weight on a Bianchi Eros frame.



Chalo wrote:

However, since I'm 6'8" with a sturdy frame (and used to be even
taller)


At my leanest (due to a combination of fanatical riding, vegan diet,
and "ethnopharmacology"), I measured 6'9" and about 220 lbs.


Hmmm. You're not geriatric; could you explain that please? Is it the
extra 100+lbs compressing you down? If so, the relevant parameter would
be torso (better, spinal column) length, not overall body length. Since
you were a fanatical bike rider you might know this figure for the two
cases. Any comments?


About BMI vs cubic law: a mouse, rat, pig, or super-morbidly obese
person is starting to approximate a cube or an oblate spheroid
http://tinyurl.com/bhskg
but a lean person is not. Both cube laws and the BMI are just
approximations, neither of which is perfect.

http://tinyurl.com/76ng8
http://www.halls.md/bmi/history.htm

BMI is pretty good, and people are interested in it not because of any
geometrical rationalization, but because it is easy to calculate from
available data and seems well correlated with % body fat and health and
lifespan. However, there is enough scatter in the data for outliers
such as yourself. %BF and especially how much you've got around the
middle are the most relevant known parameters. Special K "pinch more
than an inch" test also not too bad.a

  #16  
Old July 21st 05, 05:16 PM
David Damerell
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Default maximum weight on a Bianchi Eros frame.

Quoting 41 :
About BMI vs cubic law: a mouse, rat, pig, or super-morbidly obese
person is starting to approximate a cube or an oblate spheroid


But the square-cube law has nothing to do with the actual shape of the
body in question.
--
David Damerell Distortion Field!
Today is First Mania, July.
  #17  
Old July 21st 05, 07:41 PM
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Default maximum weight on a Bianchi Eros frame.

On 21 Jul 2005 17:16:24 +0100 (BST), David Damerell
wrote:

Quoting 41 :
About BMI vs cubic law: a mouse, rat, pig, or super-morbidly obese
person is starting to approximate a cube or an oblate spheroid


But the square-cube law has nothing to do with the actual shape of the
body in question.


Dear David,

Aha! It's a law!

So that's why a tall giraffe weighs more than a shorter
elephant!

And why a twenty-foot tapeworm weighs more than a ten-foot
python!

And why I weigh more than a 600-lb gorilla!

Carl Fogel
  #18  
Old July 21st 05, 08:15 PM
Chalo
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Default maximum weight on a Bianchi Eros frame.

41 wrote:

Chalo wrote:

However, since I'm 6'8" with a sturdy frame (and used to be even
taller)


At my leanest (due to a combination of fanatical riding, vegan diet,
and "ethnopharmacology"), I measured 6'9" and about 220 lbs.


Hmmm. You're not geriatric; could you explain that please? Is it the
extra 100+lbs compressing you down? If so, the relevant parameter would
be torso (better, spinal column) length, not overall body length. Since
you were a fanatical bike rider you might know this figure for the two
cases. Any comments?


Once you stop getting taller, you start getting shorter, regardless of
age. It's more pronounced for me than for many other folks probably
because I broke my back in two places as a teenager, but no doubt also
due to my unusual height and weight.

I have never known my back length; only overall height and standing
inseam. But since my inseam has not noticeably changed and my overall
height has, that sort of narrows down the possibilities.

Perhaps it's my head getting flatter? :^)

About BMI vs cubic law: a mouse, rat, pig, or super-morbidly obese
person is starting to approximate a cube or an oblate spheroid
http://tinyurl.com/bhskg
but a lean person is not.


It doesn't matter what the shape is, volume is still directly
proportional to the cube of the length.

Both cube laws and the BMI are just
approximations, neither of which is perfect.


Not perfect, sure, but consider this: If two bodies are exactly
identical in every respect except overall scale, then BMI considers one
of them to have a "better" weight than the other. Obviously this is
fallacious.

BMI is pretty good, and people are interested in it not because of any
geometrical rationalization, but because it is easy to calculate from
available data and seems well correlated with % body fat and health and
lifespan.


Unusually tall height is correlated with shortened lifespan, but it's
simply wrong to think that a very tall person will live longer by being
underweight and thus having a "normal" BMI. I would expect the
opposite. Likewise, very short people live longer on average than
normal-sized people, but it would not be to their benefit to gain
weight in order to normalize their BMI.

Anyway, if BMI is fundamentally a statistical tool, then it's bogus to
use a purely geometrical (and purely broken) formula to calculate it.
The more you look at it, the more it looks like plain old hokum.

Chalo Colina

  #19  
Old July 21st 05, 09:09 PM
Peter Cole
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Default maximum weight on a Bianchi Eros frame.

David Damerell wrote:
Quoting Llatikcuf :

If you refer to the simple geometric principle that volume is
proportional to height^3, then you'll see that 6'8" and 300 lbs is
equivalent to 6'0" and 219 lbs., or 5'6" and 168 lbs. That's normal
for fit men of heavy build at those heights.


that's not how I remember health class-


[BMI]

Indeed, it is obvious that BMI is bogus for people of unusual height
precisely because it does not take account of the square-cube law.


We've been over this before. BMI works for me (6'10"/230lb), so does the
max HR formula. As unusual as I am statistically, I'm only 17% or so
taller than the average male of European descent, probably less than
that for my ancestral gene pool (Dutch). As far as I know, I'm to scale,
in that all my parts, including eyes (opthalmologist says) and teeth/jaw
(dentist says) are just that much bigger. I'm no "bean pole", nobody
ever called me skinny, I'd say I have an average build/frame, just
scaled up a bit. For my average build, the BMI seems to scale well,
perhaps not perfectly, as my body fat is low-ish and the BMI has me at
the high end of normal/recommended. 17% isn't a huge difference
geometrically (although it seems huge to most people appearance-wise).
Another non-linearity is density -- bones get bigger/heavier as they get
longer, though I'm not sure exactly how much. It's interesting to see
such physically different cyclists as Pantani/Hamilton vs.
Hincapie/Indurain compete over the same courses. It seems there may be a
disadvantage to being too big or too small when it comes to endurance
athletics.

There is a wide variation in build/body types. I guess the old
endo/ecto/meso-morph type model is no longer used, but I've seen a few
attempts to adjust the BMI for categories of body type.

More importantly, there was just a study that linked large skull size to
high intelligence. This pleases me because I can never find a hat big
enough either.
  #20  
Old July 22nd 05, 12:33 AM
Chalo
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Posts: n/a
Default maximum weight on a Bianchi Eros frame.

Qui si parla Campagnolo wrote:

Chalo wrote:

Qui si parla Campagnolo wrote:


Maybe you ought to see how much the gent weighs before you assume that
a square taper crank/BB will be unsafe. Many have ridden square taper
w/o problem for decades, and to paint it as 'unsafe' for nearly anybody
is not accurate.


As I've told you before, I have broken two square tapers under pedaling
loads alone; one when I weighed about 240 lbs., and the other when I
weighed about 260 lbs.


And as I have mentioned, there is something amiss in the ones you used
and I do not think it's a design flaw.


I was willing to believe that after I broke the first one. I continued
to use a square taper and it cost me my six top front teeth. I would
be a damn fool to give a proven piece of junk like that another chance
to hurt me-- as would anybody over 220 lbs., in my opinion.

Many as heavy and strong as you
or more so, have used square taper for decades w/o any failures.


And several people who post here in this group have broken them. It's
not rare and it's the result of just plain bad engineering.

Chalo Colina

 




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