Taking metal away from the middle of something weakens it, but makes it lighter. If there are internal flutes potruding into the inside hollow of the seatpost, these would add strength. I think the flutes cut into the outside are there for looks and nothing more.

I was under the impression that fluting in rifle barrels was done pretty much only for heat dissipation, because aren't most of the fluted barrels milled?

The example of butted vs. straight gauge tubing is totally unassociated in so much as engineering design principles are concerned.

A fluted seat post can be more closely associated with a prismatic member of constant section along it's length, where the cross-sectional area of the material in the post can be reduced, the effective outside diameter maintained, and losses of lateral Engineering stiffness (E*I, where E is a material constant and I is moment of inertia, in reality a function of the cross sectional geometries) minimized. This can, of course, be combined with improvement of material selection and processing to optimize other variables.

The design principles of non-prismatic members (i.e., butted tubing) would be rather different, not to mention that the math goes beyond the realm of 8th grade algebra. The only similarity is that they both intend to reduce structural weight while trying to minimize losses of stiffness and at the same time maximize loadings at the point of failure.


Edit: As an aside, he who claims that his frames and/or cranks don't flex or compress/tense under loading (I've even seen people say "zero flex" on these very same forums) could stand a refresher in the mechanics of materials. It may be imperceivable, or dare I say "negligible," but zero is an important four letter word.

Sydney, assertiveness and loud proclomations are symptomatic of insecurity and a poor substitute for respectful idea exchange. But whether you happen to be correct (sometimes) , or when you happen to be somewhat less than correct as you also sometimes are, you are always consistently obtuse and ill mannered.

That's rude!

I thought Sydney's response to your lame comments was remarkably restrained.

Is this what y'all are talking about:

http://www.bikepro.com/arch_products...prade_side.jpg
http://www.bikepro.com/arch_products...rade_front.jpg

Note the flutes look to be part of the cast, not machined in later. The machining is only to set the final OD of the post. So it could be structurally stronger and save on raw material as a cost savings.

I have this seatpost (SR Laprade) on my early 1980s Centurion.

Al

I asume you mean aren't the flutes themselves milled, and the answer is yes. Heat dissipation, weight reduction & stiffness are all reasons for the flutes; having surfaces at contrasting angles adds stiffness. If you know rifles, you know the barrels have specific flex properties; in fact, some are referred to as "whippy". Flutes can help to overcome some of this, and offer the other benefits mentioned as well.

As for the seatposts, I never really cared for flutes. Although Campy offered them at one point it was usually the cheaper models that had them, and I always associated flutes with less-than-top quality. A personal perception, of course, but there you have it.

I agree. For lightness, I prefer the ovalized tubing Ritchey offers; thinner on the sides, thicker on the front & rear where necessary. Those used to be made by Nitto; anyone know if they still are?

Some are certainly ill equipped to be masquerading as the correct or less than correct police. :rolleyes:

I recently found a new old stock 1982 Dura-Ace seatpost which is fluted and it looks very nice on my touring bike. It is easier to adjust and much lighter then what I had - not that it matters much on a touring bike.

Super Record posts were fluted. Nuovo Record posts were not. Super record was the top of the line.

Yeah, that's what I was referring to. The problem was by the time the Super Records came out the most common fluted post was that SR shown a few posts back, and that is what all the others looked like (to me). Like I said, personal perceptions...