[rollei_list] Re: Bikes
- From: Jerry Lehrer <jerryleh@xxxxxxxxxxx>
- To: rollei_list@xxxxxxxxxxxxx
- Date: Thu, 08 Jun 2006 00:57:19 -0700
Frank,
Most all structural metals have identical specific stiffness, EXCEPT
Beryllium, whose specific stiffness is 6 times higher. Tubular beryllium
replaced the aluminium tone arm shaft on my Linn Itok tone arm.
Jerry
Frank Dernie wrote:
> I know nothing about bikes but I am very familiar with these
> materials. Steel and Ally have more or less identical specific
> stiffnesses so any difference will be due to the geometry - for
> example the larger diameter tubes used in the ally frame for strength
> will result in stiffer welded junctions. Carbon is nothing like either
> steel or ally. The mechanical properties depend on the layup and
> material choice, there is a huge variation in stiffness of different
> fibres unlike metals where the strength can vary greatly between
> alloys but the stiffness not much at all. The fibre orientation and
> type of fibre will have a much bigger effect in carbon than metal
> though the geometry of the joints will have the biggest influence on
> stiffness. Carbon can have significant internal damping, depending on
> resin system. Metals have negligible internal damping.A carbon frame
> has more potential than a metal one, I would expect an optimised
> carbon frame to cost between 10 and 100 times more than a metal one so
> they probably either don't exist or the metal ones are much more
> profitable :-)Frank On 8 Jun, 2006, at 02:18, Douglas Nygren wrote:
>
>> One further thought about bikes that pertains to cameras.
>>
>>
>>
>>
>> New developments in bike design and construction have led to many
>> carbon fiber (ie. plastic) and aluminum bikes. They have displaced
>> the old standard whcih were made of metal, often called
>> "Cro-malloy."
>>
>>
>>
>> The carbon and aluminum bikes are lighter. Some are more rigid than
>> the steel. They climb well, but they don't descend as well. They hop
>> with every bump. The steel absorbs this better. On a long ride, the
>> aluminum beats the rider up. They are so stiff that the very quality
>> that allows them to climb better--ie. the stiffness that transfer
>> the energy better--also allows the energy from bumps to return
>> upward and into the rider. On a long ride, this does a number on the
>> rider. Steel treats the rider better.
>>
>>
>>
>> I think you'd be hard pressed to find a steel bike on the Tour de
>> France these days. Carbon is in, and it's a lot like aluminum.
>>
>>
>>
>> I perfer steel, and I prefer film to digital. I'm afraid I'm
>> becoming anachronistic.
>>
>>
>>
>> Doug
>
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