why is hallow stuff stronger?!?!?!

thnx for the reiteration gilby. i'm not an engineer but i think i got i
the first time, but seems that others didn't so i tried to
paraphrase(albeit poorly) for them

--
markf - movie nerd

stuck in iowa and unemployed.
------------------------------------------------------------------------
markf's Profile: http://www.unicyclist.com/profile/8102
View this thread: http://www.unicyclist.com/thread/36977

I really like Gilby's explanation. Being as I still have yet to get a
chance at going to an engineering school, I've always understood things
that hollow works because you increase the diameter of the tube in
proportion to the drop in strength from losing the center of the tubing.
The larger the diameter, the larger the distance that the material is
from the center of the axis on which force is transmitted. This means
that the same amount of force is spread over a larger area, allowing for
a lessened need for material to absorb that force. Correct me if I'm
wrong, but isn't it true that the larger the tubing on a bike frame, the
thinner the walls (assuming the same application of the frame).

The new Koxx cranks are solid aluminum, I think.

Not everything is hollow, but that can just be due to limitations of
manufacture. Look at some versions of the Steve Howard frames. If there
were such thing as a bit that could precisely drill the length of one of
his frames, I'm sure he would use it. Also, it is notable how on his
frames the edges of the legs are always far more substantial than the
centers. This is a 2D version of making something hollow.

--
gerblefranklin - Trials Unicyclist

http://gallery.unicyclist.com/Trials-Muni

"Peace cannot be kept by force. It can only be achieved by
understanding."-Albert Einstein
------------------------------------------------------------------------
gerblefranklin's Profile: http://www.unicyclist.com/profile/4295
View this thread: http://www.unicyclist.com/thread/36977

Hollow materials are used because of a weight issue, not a strength
issue. You can get sufficient (not necessarily equal) strength out of a
much lighter design; i.e. hollow instead of solid.

--
toddw9 - you win, you always do!
------------------------------------------------------------------------
toddw9's Profile: http://www.unicyclist.com/profile/4466
View this thread: http://www.unicyclist.com/thread/36977

gerblefranklin said:

*I really like Gilby's explanation. Being as I still have yet to get a
chance at going to an engineering school*

If you do go in to engineering in college you'll learn all about this in
your engineering statics course, probably during your junior year. Or
you could get ahold of an engineering statics textbook from the library
and try to make sense of the math and the concepts on your own.

And yes, Steve Howard is making a bit of a I beam style structure to
give the fork legs some extra strength while keeping the weight down.
It's the 2D equivalent of a hollow tube.

--
john_childs - Guinness Mojo

john_childs (at) hotmail (dot) com
Gallery: '' (http://www.unicyclist.com/gallery/john_childs)
------------------------------------------------------------------------
john_childs's Profile: http://www.unicyclist.com/profile/449
View this thread: http://www.unicyclist.com/thread/36977