Just to be a pedant: Most engineering metals have very similar "specific" moduli of elasticity: modulus divided by density. E.g. while steels have a modulus that is roughly three times that of typical aluminium alloys, the d ensity is also approximately three times. Similar ratio holds for Titanium. Different alloys and heat treatment processes can very significantly chang e the strength of the material, but they have virtually no effect on the mo dulus.
So in the case of rims if you use a higher strength alloy you n eed less of it for strength, so actually your stiffness will go down for th e same shape - but of course in practice it all depends on the rim geometry , spoke count and pattern etc.
In the case of frames, the high strengt h alloys let the wall thickness and hence weight be reduced, but for more-o r-less fixed tube outside diameters (as in most steel frames before "oversi ze" tubing appeared) this means that the stiffness of a high end frame WILL be less than a clunker. Same stiffness material, more of it in the clunker because it needs it to be strong enough.
As an aside, we tested a few frames for bottom bracket to headtube torsional stiffness as part of a pro ject I had some uni students on last year. The 1970s "gas-pipe" clunker was stiffer than a current carbon-fibre Scott CR1 (although more than 3 x heav ier..), almost 3 time stiffer than a 531C tubed frame, and only a few % les s stiff than a Cannondale CAD3. How stiff is stiff enough? Who knows...
Off soap-box.
Mark Battley Auckland, NZ
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>>
The
old
MA2
is
softer
old
technology
material.
>>
The
new
aero
type
rims
and
material
s
are
far
stiffer
and
stronger
so
you
can
>>
u
se
less
spokes
and
be
plenty
rigid.
>>
Look
at
all
the
3
&
4
spoke
wheels
of
today.
>I'd
just
add
that
the
added
stiffness
of
aero
sectio
n
Al
alloy
rims
is
>not
due
to
materials
changes
but
the
increased
sectional
area,
which
>is
why
t
hose
aero
rims
are
heavier
as
well.
All
post
WW
II
Al
alloys
>(and
really
all
engineering
metals,
Be
ryllium
notably
excepted)
have
>similar
moduli
of
elas
ticity.