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  1. #576
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    Quote Originally Posted by aclinjury View Post
    my personal experience is I have always put out the highest avg power and highest normalized power when I'm hammering on my carbon-ti (flexy) bike on the flat, when compared to my full carbon bike (which is definitely stiffer). My heart rate would stay the same yet amazingly my avg power would be like 20 watts more in a 5-10 minute hard effort. I do like the springy feeling of the bottom bracket of the carbon-ti bike.

    on another note, I think by now, the mantra that carbon frame can be both "stiff laterally and compliant vertically" is pie-in-the-sky wish. No way to make a bike both stiff and compliant with carbon fiber even though in theory this should be possible (by adjusting carbon layups). Now, bike companies are relying on other tricks like put using an "elastomer" in the seattube or headtube, lol. So they've have given up on the "stiff and compliant" dream, just insert a piece of elastomer now.
    This (your post and the greater context of the recently referenced Podcast which I listened to) is fascinating as I ditched an Aero Felt AR for the thinner tubed and more flexible F. I wrote a post about it somehwere here but, the gist was that in a straight line after a year of roll down tests, and all kinds of other power related testing, I could only come up with about 0.25mph faster on the AR. Some position. Same wheels/tires and group. Some power meter. And by same wheels/power meter I mean I swapped back and forth for the test.

    However, when it came down to racing, I don't know man. I always ended up in a better position or was able to maneuver myself quicker (whatever) to be in the right spot with the F which is a large part of doing well. Could be total bullshit but, it was apparent enough that I sold the AR.

    Maybe they will come up with a thinner walled aero frame soon.

  2. #577
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    Quote Originally Posted by bradkay View Post
    How about a design that instead of "using an elastomer" just allows the seattube or the steertube to flex fore and aft while limiting it from flexing side to side?
    though I don't own a Trek, but their "isospeed" system where they make the seatpost articulate (thus flexible) without resorting to an elastomer is a great idea, I was impressed when I tried it on the Madone 9. I ride a carbon-ti Serotta Ottrott, and when i sit on most pure carbon bikes I always think they're too stiff and harsh, but the Domane makes me think twice about Trek's "isospeed" system. Having said that, the Domane is still not quite on par with my Serotta Ottrott when it comes for comfort. Elastomer is so 1990, back in those days early mountain bikes had used them, lol

  3. #578
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    Quote Originally Posted by woodys737 View Post
    This (your post and the greater context of the recently referenced Podcast which I listened to) is fascinating as I ditched an Aero Felt AR for the thinner tubed and more flexible F. I wrote a post about it somehwere here but, the gist was that in a straight line after a year of roll down tests, and all kinds of other power related testing, I could only come up with about 0.25mph faster on the AR. Some position. Same wheels/tires and group. Some power meter. And by same wheels/power meter I mean I swapped back and forth for the test.

    However, when it came down to racing, I don't know man. I always ended up in a better position or was able to maneuver myself quicker (whatever) to be in the right spot with the F which is a large part of doing well. Could be total bullshit but, it was apparent enough that I sold the AR.

    Maybe they will come up with a thinner walled aero frame soon.
    I'm a classic round tube and steel guy, never did embrace aero frame, maybe because i know aero frames are like chasing the latest tech, their lifecycle is short, you find them on fleabay shortly thereafter!

  4. #579
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    Quote Originally Posted by woodys737 View Post
    This (your post and the greater context of the recently referenced Podcast which I listened to) is fascinating as I ditched an Aero Felt AR for the thinner tubed and more flexible F. I wrote a post about it somehwere here but, the gist was that in a straight line after a year of roll down tests, and all kinds of other power related testing, I could only come up with about 0.25mph faster on the AR. Some position. Same wheels/tires and group. Some power meter. And by same wheels/power meter I mean I swapped back and forth for the test.

    However, when it came down to racing, I don't know man. I always ended up in a better position or was able to maneuver myself quicker (whatever) to be in the right spot with the F which is a large part of doing well. Could be total bullshit but, it was apparent enough that I sold the AR.

    Maybe they will come up with a thinner walled aero frame soon.
    Aero bikes seem relative to ability. From the tests I've seen done by GCN, Cyling Magazine, Bike Radar etc is that you don't see watt savings, improved efficiency until nearly 40 KMPH. Last data dump on Strava showed average man rides about 15mph, at those speeds, the difference between Aero and comfort light bike is nearly nil. The bike manufacturers state that too, see some marketing material that claim 50 watt savings @ 50 kmph or similar. If I was Sagan that would make a difference, but I can't ride 30 mph, not even close, i average 18? So based on that, I'll stick to the light weight standard bikes.

  5. #580
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    Another empirical observation

    I ride 3 bikes
    A hi-modulus 13.5lb NeilPryde BURA SL
    A non hi-mod 16lb gen 1 Scott Addict
    A 23lb 1986 Steel Colnago L'eroica bike

    The interesting contrast is the Addict compared to the BURA. The BURA is much stiffer than the Addict in the front end and bottom bracket, it accelerates more 'abruptly' although I won't say it's faster. The BURA is so stiff that it's harder to ride smoothly, and I'm convinced harder to apply consistent power inputs. One might suggest reducing the amount of carbon layup, but this would only result in a fragile frame.

    The BURA is great for crits, and maybe hillclimbs, but I'll be swapping it out for something new next year for general riding.

    Ironically, the 8-pound-heavier Colnago is amazingly smooth and enjoyable to ride, and is just as fast as the carbon machines on flat ground.

    Summary observation: Stiffness beyond a point is counterproductive to smooth power transfer (and general handling of course). This is why the top-rated frames such as Specialized SL5 have worked very hard on that blend.

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