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  1. #426
    \_(ツ)_/ Ygduf's Avatar
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    TY. now to find a flat road.

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  2. #427
    fuggitivo solitario echappist's Avatar
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    Quote Originally Posted by Ygduf View Post
    Aero "savings" are often listed in grams of drag.

    What is a reasonable amount of "grams of drag" at like 40km/hour for a cDA of 3?
    back of hand mnemonic

    at 30 mph, 50 grams = 5 watts = 0.005 m^2 (CdA) = 0.5 sec/km

    actually it's more like 45 grams, but this is back of the envelope

  3. #428
    gmt Grumpy McTrumpy's Avatar
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    The aerolab data from last night indicated a CdA below .2 for the first time ever. It's not easy to estimate Crr, but I tend to err on the side of too much, choosing a number that is higher than what I measure on my rollers, but not so high that it puts things way out of proportion. CdA worked out to be .1991

    Additionally, I have to estimate transmission efficiency which I tend to keep around .965

    The change? Replacing the long Uvex with a Giro Selector has lowered the CdA by a measurable amount, so far as I can tell. (~.0039)

  4. #429
    Senior Member aaronmcd's Avatar
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    Is it tacky to use electrical tape to hold the aerobar plugs in if they like to come out (clip ons, so no bar end shifters)?

  5. #430
    \_(ツ)_/ Ygduf's Avatar
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    do what you got to do.

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  6. #431
    Senior Member aaronmcd's Avatar
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    I have two random questions.

    While racing a time trial, a hill causes the racer's velocity relative to wind to fall below x, reducing the effect of aerodynamic drag and prompting the racer to optimally leave the aerobars for more power. Solve for x.

    Also, here is a random theoretical question:
    My TT on Sunday is uphill out and downhill back. But say a time trial is the reverse - starting with a descent and finishing with a climb. Should one carry an aero bottle, filled with water and installed with a release valve on the bottom in order to use gravity for an advantage on the first half, and dump the water for the climb?

  7. #432
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    aero question: watching world championships, the announcers reiterated a number of times that the riders need a rounded back or hunchback for better aerodynamics as opposed to a flat back. is this an across the board truth? rider specific? complete hogwash?

    they also said one of the riders lost 6 kg in the 4 weeks leading up to the event so they could climb better. That's 13 pounds in old money, which for a prof cyclist doesnt sound very realistic to me, so my confidence in the proclamations of the announcing crew is low.

  8. #433
    fuggitivo solitario echappist's Avatar
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    if the said announce is a certain Mr. Liggett, well, you have your answer there

    now that said, at a certain back angle below horizontal, you actually incur more drag the lower you go. but that's still a bit to go from flat back
    Last edited by echappist; 09-26-14 at 11:23 AM.

  9. #434
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    Going to get fitted to my new (to me) first ever TT bike. Is there any relationship between the saddle I use on a road bike and the saddle on a TT bike? Should I just bring the loose saddles I have in my spares box, or will I likely need something entirely different?
    Regards,
    Chuck

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  10. #435
    Senior Member shovelhd's Avatar
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    Most guys I know use a TT or triathlon specific saddle.

  11. #436
    Senior Member island rider's Avatar
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    With all the aero advantages on new Tri specific (Non-UCI) bikes, is there any reason a Cat 4 -3 for whom participation in a national event is extremely unlikely shouldn't buy a Shiv or something like it and benefit from those gains?
    "I think drivers become like dogs when they see a bicycle fly by at 40mph. Instinctively, they just want to give chase, catch them, and eat them." - Papa Tom

  12. #437
    Senior Member shovelhd's Avatar
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    Who gives a ****. Buy what you want and **** what anyone else thinks.

  13. #438
    Senior Member furiousferret's Avatar
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    Quote Originally Posted by island rider View Post
    With all the aero advantages on new Tri specific (Non-UCI) bikes, is there any reason a Cat 4 -3 for whom participation in a national event is extremely unlikely shouldn't buy a Shiv or something like it and benefit from those gains?
    The Shiv TT is not much of a gain in the tunnel, unless you have the one with a fairing that covers the front brake. The real deal breaker for me would be that water bladder, since you can drink and stay aero that could add up to a ton of time saved in a long tt. So long as you race with it empty I would not care (that's coming from another competitor's perspective).

  14. #439
    Senior Member island rider's Avatar
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    Quote Originally Posted by furiousferret View Post
    The Shiv TT is not much of a gain in the tunnel, unless you have the one with a fairing that covers the front brake. The real deal breaker for me would be that water bladder, since you can drink and stay aero that could add up to a ton of time saved in a long tt. So long as you race with it empty I would not care (that's coming from another competitor's perspective).
    That's the thing, not the Shiv TT, the Shiv Tri. It's not UCI legal, but most races up to the national level don't require UCI compliance and/or specifically allow bikes like this.
    "I think drivers become like dogs when they see a bicycle fly by at 40mph. Instinctively, they just want to give chase, catch them, and eat them." - Papa Tom

  15. #440
    gmt Grumpy McTrumpy's Avatar
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    I have one of those nosecone Shivs. I've gotten it down to .2 CdA on calm days according to Aerolab.

    If I were going to Nationals I guess I would find a new frame but I'm hoping they relax some of the UCI guidelines and legalize it. They have already relaxed a bunch of guidelines and this model was originally designed to meet UCI specs until the McQuaid regime killed it (after it had won worlds with Cancellara).

    I don't intend to go to Nats until I have seen TTs in the 29mph range (or possibly if they choose to have it in Pennsylvania again).

  16. #441
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    Quote Originally Posted by island rider View Post
    With all the aero advantages on new Tri specific (Non-UCI) bikes, is there any reason a Cat 4 -3 for whom participation in a national event is extremely unlikely shouldn't buy a Shiv or something like it and benefit from those gains?
    Quote Originally Posted by furiousferret View Post
    The Shiv TT is not much of a gain in the tunnel, unless you have the one with a fairing that covers the front brake. The real deal breaker for me would be that water bladder, since you can drink and stay aero that could add up to a ton of time saved in a long tt. So long as you race with it empty I would not care (that's coming from another competitor's perspective).
    the nosecone shiv only proved to be more aero than the UCI-legal shiv TT at yaw > 7*. it is slightly slower than the shiv TT between 0 & 7.

    the newer model shiv (tri) was designed to allow triathletes to store more $hit in their frame rather than hanging off of it, as well as to be easier to work on and to fit more people (it's a much taller frame vs the shiv tt long & low, so it appeals to a lower common denominator). it's slower than the shiv TT from 0-7 and slower than the nosecone shiv >10. they viewed it as a win because it added features that many customers wanted while doing a pretty good job with aerodynamics. the UCI-legal thing doesn't matter to a large set of customers.

    for a rider actually doing TTs (not ironman triathlons @ 20mph), >10 yaw -- even >7* yaw -- is not all that common. (yes, yes, there are examples to the contrary, but a rider going 27, 28, 30mph needs to experience pretty high winds at actual ground speeds, which is not as common as we tend to think.

  17. #442
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    Quote Originally Posted by Grumpy McTrumpy View Post
    If I were going to Nationals I guess I would find a new frame but I'm hoping they relax some of the UCI guidelines and legalize it. They have already relaxed a bunch of guidelines and this model was originally designed to meet UCI specs until the McQuaid regime killed it (after it had won worlds with Cancellara).

    Quote Originally Posted by Grumpy McTrumpy View Post
    I don't intend to go to Nats until I have seen TTs in the 29mph range (or possibly if they choose to have it in Pennsylvania again).
    USAC made an exception for the nosecone shiv. not sure if it was for 1 year only, but you might want to look into that.
    i kinda understand this logic and also kind of don't. i've had a bunch of friends not show up to nationals because they wanted to wait until they felt like they could win and failed to realize that by not showing up they had no idea of how far they truly were from their goal. IMO, it is helpful to go out and ride vs the best guys on the same day, same course, same conditions. a good a$$-kicking is supremely motivating.

    the guys who save it until they are ready sometimes waste some time in learning that lesson.

    no one is ever really "ready".

    masters nationals in 2016 in NC, grumpy. close enough to PA for ya?

  18. #443
    gmt Grumpy McTrumpy's Avatar
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    maybe.

    depends on my form. Plus, TT frames aren't cheap

  19. #444
    gmt Grumpy McTrumpy's Avatar
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    As far as the asskicking goes, I don't have to go to NC for that. Several of the nearby stage races tend to feature National champs from different countries, plus people who finish close to them.

  20. #445
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    Quote Originally Posted by Grumpy McTrumpy View Post
    maybe.

    depends on my form. Plus, TT frames aren't cheap
    i checked to be sure; as of last year they were still allowing the nosecone shiv as an exception to the 3:1 rule. see bottom of page 1.

    the TT course in SLC is a very cool one, if you are so inclined. there are some hills.

    just saved you a few grand, so maybe you can use that for travel. ;-)

  21. #446
    Senior Member island rider's Avatar
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    Quote Originally Posted by tetonrider View Post
    the nosecone shiv only proved to be more aero than the UCI-legal shiv TT at yaw > 7*. it is slightly slower than the shiv TT between 0 & 7.

    the newer model shiv (tri) was designed to allow triathletes to store more $hit in their frame rather than hanging off of it, as well as to be easier to work on and to fit more people (it's a much taller frame vs the shiv tt long & low, so it appeals to a lower common denominator). it's slower than the shiv TT from 0-7 and slower than the nosecone shiv >10. they viewed it as a win because it added features that many customers wanted while doing a pretty good job with aerodynamics. the UCI-legal thing doesn't matter to a large set of customers.

    for a rider actually doing TTs (not ironman triathlons @ 20mph), >10 yaw -- even >7* yaw -- is not all that common. (yes, yes, there are examples to the contrary, but a rider going 27, 28, 30mph needs to experience pretty high winds at actual ground speeds, which is not as common as we tend to think.
    I've just got TT bike money set aside and burning a hole in my pocket. I just sold my last one and need a replacement. I have no vested interest in going with one versus another so I'm looking for reasons.
    "I think drivers become like dogs when they see a bicycle fly by at 40mph. Instinctively, they just want to give chase, catch them, and eat them." - Papa Tom

  22. #447
    Resident Alien Racer Ex's Avatar
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    Quote Originally Posted by tetonrider View Post
    i checked to be sure; as of last year they were still allowing the nosecone shiv as an exception to the 3:1 rule. see bottom of page 1.
    They have a rulebook? Really? Then why do these officials make s*** up as they go along?

    Quote Originally Posted by tetonrider View Post
    the TT course in SLC is a very cool one, if you are so inclined. there are some hills.
    And bison. If you hit and kill one you get to keep the tenderloin.

  23. #448
    Resident Alien Racer Ex's Avatar
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    Quote Originally Posted by aaronmcd View Post
    While racing a time trial, a hill causes the racer's velocity relative to wind to fall below x, reducing the effect of aerodynamic drag and prompting the racer to optimally leave the aerobars for more power. Solve for x.
    Trick question. The answer is a well trained TT specialist never leaves the aero bars because there is no positional differentiation in power.

  24. #449
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    Helmets

    I was gifted an older Lazer TT helmet with the long-ass tail on the back. I frankly question my ability to use it properly, since I'm not sure I can bend my neck that much for a half hour or so. I'm considering getting myself a Specialized Evade to use instead on the assumption that a shorter tail will screw me up less when my head's not in perfect position. Another fact bearing on the problem is both my new-to-me TT bike and my new road bike are flat black, and the Evade is available in...wait for it!...flat black.

    Opinions?
    Regards,
    Chuck

    Demain, on roule!

  25. #450
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    Quote Originally Posted by Racer Ex View Post
    Trick question. The answer is a well trained TT specialist never leaves the aero bars because there is no positional differentiation in power.
    My coach told me to stand for steep hills and going to the bullhorns is ok below 15 mph because you can breathe better. I take it you disagree?
    ...

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