Re: New Cervelo Model
- From: Luke <lucasiragusa@xxxxxxxxxx>
- Date: Tue, 28 Feb 2006 16:39:54 -0500
In article <jack-79F770.12063328022006@xxxxxxxxxxxxxxxxxxxxxxxxxxxx>,
Michael Press <jack@xxxxxxx> wrote:
In article
<1141072940.623266.264910@xxxxxxxxxxxxxxxxxxxxxxxxxxxx>,
amit@xxxxxxxxxxxxxxxxxxx wrote:
This is the new Cervelo model :
http://www.cyclingnews.com/photos/2006/feb06/hetvolk06/index.php?id=live/DSC
02027
from what I've heard the seatstays contribute very little to the
structure. the chainstays and seatube are strong enough that the bike
would be ridable without seatstays.
Where have you heard this?
Consider an axis through the rear axle, directed fore-aft,
and parallel to the ground. Torque at the axle about this
axis is normally resisted by seat stays. Remove the seat
stays and that torque must be resisted by the joint at the
chain stays and the bottom bracket.
More generally, the two chain stays, two seat stays, seat
tube, and rear axle form a tetrahedron. In a tetrahedron
with rigid members the joints could be pinned without
compromising the strength of the structure, making the
tetrahedron an efficient spacial structure. Analogously,
a triangle of rigid members can be pinned at the joints
and yet be very strong in its plane. Contrast this with a
pinned square; it will flop around when subject to stress.
In the real world the rigid members actually flex;
therefore the joints must be built to resist this flex. So
we put a bridge between the chain stays near the bottom
bracket, and a bridge between the seat stays near the seat
tube.
How do you account for designs such those of Softrides[1]? I'm no
proponent of this approach; chainstays of dimensions equal to those of
motorcycle swingarms strike me as incredibly ugly. Is this a case of
simply over-engineering the chainstays and BB junction to handle the
torsional loads?
I'm unsure from the photo whether Cervelo's design utilizes CF
chainstays; perhaps advances in the application of that material may be
able to provide strength comparable to that Softride achieves with its
gargantuan aluminum stays.
Luke
1.
http://www.softride.com/product.asp?p=13
.
- References:
- New Cervelo Model
- From: amit
- Re: New Cervelo Model
- From: Michael Press
- New Cervelo Model
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