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  1. #1
    RoadBikeReview Member
    Reputation: Ventruck's Avatar
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    Mar 2009

    Neato article on VN about seatposts

    Found in the new VN issue, but some pics from the online article. Sorry, doesn't look like I can pull up bigger ones. 2nd pic is most troublesome, but you can maybe squint the key points. Added key notes. Maybe you "know all the answers", but if you're ever curious about quantitative data like me,,,

    The winners in the vibration damping test, and the only ones under 0.6 G of acceleration, were the FSA K-Force Light SB25 carbon seatpost and the Specialized S-Works FACT Carbon post...

    The poorest performer in this test, with more than twice the amount of Gs as the top three performers, was the Ritchey WCS carbon straight post.

    How Seatpost Material Affects Vibration
    The Ritchey WCS setback seatposts in carbon and aluminum share the same design and are both very lightweight relative to others in their class. When it comes to vibration damping, the carbon version outshines its aluminum cousin, albeit not by a huge margin—less than 0.1 G. Bottom Line: Carbon seatposts absorb road vibration better. Five of the top six posts in this test were carbon; the only aluminum post in the top six is built with pivots and an elastomer.

    Damping: Setback vs. Straight
    ...Our test showed that having the saddle pushed back on a straight seatpost resulted in the rider being bounced around more than on a setback seatpost with the saddle pushed forward....Bottom Line: Setback posts offer more vibration damping than straight posts; how much more will vary by manufacturer.

    Damping: Seatposts with Suspension Features
    The Specialized S-Works FACT Carbon seatpost almost won the overall test, with the Cane Creek Thudbuster/ST and Cannondale SAVE both coming in the top 1/3 overall. Bottom Line: Suspension can save your ass. Of the top five seatposts for vibration damping, three of them incorporate suspension designs.

    As you might expect, the Cane Creek Thudbuster/ST far exceeded the flex, both horizontally and vertically, of any of the other seatposts...Interestingly, the seatpost with the worst high-frequency vibration performance, the Ritchey WCS Carbon straight post, had the second-highest vertical flex reading, behind only the Thudbuster/ST...

    Due to the fact that we measured flex at the tail of the saddle, the seatposts with the lowest flex numbers were all setback seatposts:
    The stiffest seatpost, and the only one to register under 0.15 inch flex in either direction (and it did it in both) was the Thomson Masterpiece setback...

    How Seatpost Material Affects Saddle Flex
    We tested only one model in both aluminum and carbon, the Ritchey WCS. Comparing the two — both with 25mm setback — we find that the flex of the carbon model is greater in both the horizontal and vertical directions than that of the aluminum one. Bottom Line: Carbon posts deflect more than similar aluminum posts, which is good for big hits.

    Flex: Setback vs. Straight
    In all cases except one, both the vertical and horizontal flex on the setback posts were less than on the straight posts of the same make and model. That one exception was the Ritchey WCS Carbon: The vertical flex with the straight WCS post was indeed greater than that of the setback version, but the horizontal flex of the straight WCS was slightly less than that of the setback WCS, breaking an otherwise straight flush of straight over setback...

    Flex: Seatposts with Suspension Features
    As noted and expected, the flex of the Cane Creek Thudbuster/ST greatly exceeded that of all of the other seatposts. It is the only one in this test with pivots; it is designed to move a long way while others can only flex along their length. The movement of the Specialized post with the Zertz elastomer plug is quite modest; it finished in fifth in horizontal movement and seventh in vertical flex.

    Ease of Saddle Installation and Adjustment
    This was not intended to be a test of the ease of setup of the various seatposts, but given that we had to swap and quickly set up saddle positions on 14 seatposts many times over two days of testing, we learned some things about that as well. The Ritchey single-bolt design, once you figured out how to avoid dropping all of the little separate pieces, was by far the easiest and fastest to install and adjust.

    In general, when choosing between a straight or setback post (if your frame seat angle doesn’t already dictate which one you must use to achieve your desired position), a setback post will give you greater pedaling efficiency and more high-frequency vibration damping, while a straight post will give you more flex on big bumps, lower weight, and a more jarring ride on high-frequency small bumps.

    When choosing between aluminum and carbon seatposts, our tests indicate that the carbon seatpost will offer more vibration damping on high-frequency bumpy surfaces and more flex for big bumps, while also being lighter; but they are more expensive.
    Pretty much the only thing standing out to me is the Specialized post. That Zertz insert the real deal or is this a shill? Wonder how the post would perform is that insert was removed and just left the gap.

  2. #2
    Steaming piles of opinion
    Reputation: danl1's Avatar
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    Jul 2005
    Interesting. What stands out most to me is that the biggest difference seems really to be in design - setbacks to one end of the graph, straights to the other, with an outlier or two in either direction.

    What is also critical but not stated here (perhaps in the article?) is the perception threshold. Blind tested, I very much doubt the most discerning Goldilocks butt could tell the difference in any of them, other than perhaps the Thudbuster. (Maybe the Ritchey straight at the other end.)

    What also stands out to me is the complete BS of their first conclusion that "carbon is better." For two of nearly identical design but different materials, there is an insignificant difference. But a carbon post (of another design) is out-of-the-park more abusive. The proper conclusion, as is common in the frame design threads, is clear: Design far outweighs material in these matters. Someone remotely knowledgable would tell you that Ritchey could have easily made the carbon worse than the aluminum with a change of layup. This is effectively confirmed in the second conclusion in the flex tests: All brands fell neatly into line, setback vs straight, except for the Ritchey. Their conclusions say that a carbon straight would be the most flexible, yet the data show the exact opposite.

    Second conclusion (setback vs straight) is flawed, too: Proper conclusion is "If youuse something as designed, you'll get better results than if you don't." If they had taken all their measurements with saddles centered, they'd have a basis for the conclusion they drew, provided the data supported it. My guess is that testing correctly would have actually enhanced the conclusion they drew, but invalid research is still invalid.

    Third conclusion is statistically weak: Yes, three of the top five are suspension, but first is not, and only three of the top ten are. They are probably all in a statistical dead heat, if they tested several samples of each, and there's still the perception threshold question.

    This data (to my reading) doesn't suggest much, but if I were using it to choose, the combination of stiffness and damping of the Masterpiece setback looks pretty nice. In the pack on damping, nice and stiff. That would support it being so highly regarded - and having it on one bike, I can agree.

    I can also agree with their non-analytic conclusion about the Ritchey one-bolt adjustment. That first assembly will temporaily leave you with a handful of parts, but once that's sorted, it's very easy to work with.

    To your question about the Zertz: I honestly don't know. A riding buddy had them rot in his frame (likely a bad chemical reaction from cleaning chemicals or waxes, not to suggest anythign against them.) He made some feeble attempt to get replacements, but at the first sign of hassle simply dug them out and left the holes empty. By his unscientific observation, no difference. But, who knows how much he had pre-decided that. You'll hear others gush about the difference they make. I suspect the truth is down the middle somewhere.
    A good habit is as hard to break as a bad one..

  3. #3
    RoadBikeReview Member
    Reputation: Ventruck's Avatar
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    Mar 2009
    Their saddle placement setup (rearward on straight posts, forward on setback posts) in the perspective of attaining the same fore/aft position on the bike was somewhat justified, given that the testing apparatus was an accelerometer on the saddle rail as the bike was ridden on rough rollers.

    But as you noted it didn't really serve as a total control. I mean, a rider isn't taking one post or the other to mount the saddle towards the opposite extreme. That's just weird

  4. #4
    RoadBikeReview Member
    Reputation: CAADEL's Avatar
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    Jul 2011
    There's something baffling about this test. I own an Easton EC90 with zero offset, a Ritchey WCS alloy with 25mm offset and a Cannondale C3 aluminum 25mm that came stock with my bike.
    The stiffest between the 3 is the Ritchey WCS alloy. In fact it's so much stiffer compared to the Easton EC90 Zero that feels like I'm riding a different bike. The Easton is far more pleasant for long rides. Cannondale C3 is somewhere in between Easton and Ritchey.

    On the diagram the FSA and Ritchey carbon seat posts with zero offset are stiffer than the Ritchey WCS alloy. But my experience with another carbon post with zero offset tells me otherwise. Could the Easton EC90 Zero be so much better than the FSA K-force 0mm Offset or the Ritchey WCS Carbon 0mm Offset? I don't know. But the test has omitted other popular seat posts (eg. 3T, Enve, Easton) and many more questions will arise. The statistical sample is small and the repeatability of scientific observations is not clear.
    Confusing at best.

    Here's a higher resolution picture of the diagram.
    Last edited by CAADEL; 12-06-2012 at 11:37 PM.

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