Couple quick answears on bars

[nealtovsen@yahoo.com (Neal Tovsen)]

> Aluminum really wouldn't be a good choice for this
> part.
> Aluminum is ~1/3 the weight of steel, but it's also
> <1/3 as stiff as
> steel. So, the weight to stiffness ratio is roughly
> the same and you'd
> have to really bulk up the aluminum part to make it
> stiff enough to make
> it worthwhile.

Ahhh...the same sorts of things could be said about
advanced composites. Yet F1 cars use aluminum and
composites more than steel, because that logic doesn't
take design into account. Comparatively oversized,
thin-wall aluminum tubing can be both stiffer and
lighter than steel. Autotech does this with their
strut tower bars. The concept was pioneered in the
bicycle industry by people like Cannondale.
Cannondale, Trek, and similar bikes are STIFF and very
lightweight. Conversely, I've seen (and ridden) some
cheap aluminum bikes that had steel-like tubing
diameters with thicker walls to compensate. As you
suspect, they weren't any lighter than a decent steel
bike.

I think the stiffness of a well-built aluminum bar
would actually work better than steel for this
purpose, in addition to being lighter. Chromoly bikes
can be made to be almost as light as aluminum, but
they tend to have much more compliant (some would say
"spongy" or "springy", others would say "lively")
characteristics. Aluminum bicycles are often
characterized as being too stiff. Well, that't good
for us. We want a bar that is RIGID.

If I only had a TIG welder...

Neal

--- Dan Bubb <jdbubb@ix.netcom.com> wrote:
> Aluminum really wouldn't be a good choice for this
> part.
> Aluminum is ~1/3 the weight of steel, but it's also
> <1/3 as stiff as
> steel. So, the weight to stiffness ratio is roughly
> the same and you'd
> have to really bulk up the aluminum part to make it
> stiff enough to make
> it worthwhile.
> Dan
> 
> Bob wrote:
> > 
> > Stock  is 3/4''with .125 walls this can be changed
> if people want to cut
> > weight, haven't got a weight yet
> > Kicking around the thought of a handfull of tig
> welded aluminum ones.
> > Price still haven't got that figured yet
> > Mounting to the same place as Kevins with a plate
> on top to spread  presure,
> > will come with all bolts.
> > Hope to have all things figured out tomorrow
> > Bob
> > 
> > _______________________________________________
> > Scirocco-l mailing list
> > Scirocco-l@scirocco.org
> > http://neubayern.net/mailman/listinfo/scirocco-l
> 
> _______________________________________________
> Scirocco-l mailing list
> Scirocco-l@scirocco.org
> http://neubayern.net/mailman/listinfo/scirocco-l


__________________________________________________
Do you Yahoo!?
Yahoo! Mail Plus - Powerful. Affordable. Sign up now.
http://mailplus.yahoo.com