cantilever frames

[ohchusan]

anyone know why cantilever frames are called cantilever frames? i can see where a diamond frame gets its name from but cantilever?

also, is it just a style or there really benefits to be had from a cantilever frame?

sorry if this is really a stoopid Q... but i had to ask.
thanks in advance guys.

 

[deorman]

http://dictionary.reference.com/browse/cantilever?jss=0

The "cantilever" projections increase resistance to load deflection (flexing or bending) in both the vertical and horizontal planes, thereby reducing stress on the seat post/tail frame joints. They can be cut out, if the seat stays are well joined, but there will be a reduction in rigidity and strengh, i.e., more flex, and a greater chance of the frame becoming bent out of alignment.

 

[Wolf]

Ohchusan has a point, there are no cantilevers contained within the frame tubes. A cantilever by definition has only one end of the beam/tube supported or fixed, clearly the extensions on the frames are welded to the rest of the structure at both ends thus they can not truely be called cantilevers!

It is true that they reduce the stresses at the seat tube junction, in a similar way that the seat stay cross over (AKA triple triangle) does. It also effectively shortens both the top tube and down tube which goes some way to compensating for the reduced rigidity due the tubes being curved and not straight.

I think that the real reason they were incorporated was for style, with the engineering benefits secondary: If rigidity of the frame was the consideration why then use a small diameter down tube with doudle curvature that is very lacking in torsional and bending rigidity. The down tube is the most highly stressed main tube in the structure.

Still a great looking frame though after all these years and one which offers great scope for the custom builder.

 

[deorman]

I have no doubt that style was the foremost consideration. Also one less part (lower bar) assemble. Nonetheless, the attachment of the stay tubes to the down tube likely improves rigidity there as well.

 

[Wolf]

They do, as I said in the second paragraph of my post

 

[deorman]

'Zakly. Then you said doudle in the third. :lol: :wink:

 

[Wolf]

well there are two tube extensions :lol:

 

[ohchusan]

phew... i thot i'd lost this post... thanks for the input guys... so its safe to say that its a styling thing first, then a benefit thing eh?

so the cantilever part of the frame is the two tubes that run up from the rear wheel (seat stays?), joined at the top of the seat post area then down the other side attached to the downtube?... i learn sumthin new everyday.

thanks!