Advertise on Bikeforums.net



User Tag List

Results 1 to 13 of 13
  1. #1
    Senior Member ldesfor1@ithaca's Avatar
    Join Date
    Feb 2006
    Location
    Newton Ctr. MA
    My Bikes
    2 cdale Caad7. Scatantte CX/winter bike. SS commuter.
    Posts
    2,109
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)

    rocking the bike while standing/sprinting

    this is a question spawned for the sprint photos in a recent post.

    What are the pros and cons of rocking the bike so dramatically in a sprint or tough out-of-the-saddle climb?

    I know that a certain amount of rocking is nearly unavoidable, but at what point does violently rocking the bike actually begin to rob power from the rider (if at all)?
    Teammates-on-Podium O'meter: 0/n (n=total # of teammates I get to race with)
    Successful Breakaway O'meter: 0/total number of races entered

    Team/Training blogness:www.thresholdcycling.com

  2. #2
    Announcer EventServices's Avatar
    Join Date
    Jan 2005
    Location
    In the drops.
    My Bikes
    Too many and not enough
    Posts
    4,963
    Mentioned
    1 Post(s)
    Tagged
    0 Thread(s)
    There is no formula. Just go with what gets you there.

    Don't try to fight it. You'll rob yourself of more speed if you try to hold the bike straight/upright.

  3. #3
    Making a kilometer blurry waterrockets's Avatar
    Join Date
    May 2006
    Location
    Austin (near TX)
    My Bikes
    rkwaki's porn collection
    Posts
    25,598
    Mentioned
    13 Post(s)
    Tagged
    0 Thread(s)
    +1 don't try to hold it steady, and don't try to swing it. Those guys have a serious leg-to-arm strength discrepancy, so they may swing it more than us mortals just because the fight is harder.

  4. #4
    James
    Join Date
    Jul 2007
    Location
    Fairfield County, CT
    My Bikes
    2005 S-Works Roubaix Ultegra
    Posts
    484
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Would it be to put more body weight over each down stroke or is that negligible?

  5. #5
    Compressed
    Guest
    If you do it correctly you can gain a good amount of power from rocking the bike when sprinting. It's a simultaneous push pull and serves to stabilize the core, set the stage for a powerful down stroke, aid the down stroke and to anchor the front wheel.

  6. #6
    Senior Member DannoXYZ's Avatar
    Join Date
    Jul 2005
    Location
    Saratoga, CA
    Posts
    11,496
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    It depends upon which way you rock the bike. What Compressed mentioned is when you rock the bike away from the power-stroke leg. So if your right-leg is on it's downstroke, you rock the bike to the left. This requires extremely strong arms and back to counteract the leg-muscles. This effectively raises your gearing as it artificially shortens your crankarm-length. I think this is the only scenario where rocking the bike helps.

    If however, your bike is rocking towards the power-leg, that is, it rocks to the right as you're stepping down on your right-leg, then some of the leg's power is going into rocking the bike instead of driving it forward. You could probably pull up on the bars a little more in this case.

  7. #7
    Compressed
    Guest
    Quote Originally Posted by DannoXYZ View Post
    It depends upon which way you rock the bike. What Compressed mentioned is when you rock the bike away from the power-stroke leg. So if your right-leg is on it's downstroke, you rock the bike to the left. This requires extremely strong arms and back to counteract the leg-muscles. This effectively raises your gearing as it artificially shortens your crankarm-length. I think this is the only scenario where rocking the bike helps.
    That's exactly what I was referring to, good explanation. This is probably why I haven't completely lost my upper body developed from years of rock climbing.

    see



    and
    http://www.youtube.com/watch?v=Ji_XcHvJvac

  8. #8
    Super Moderator
    Join Date
    Feb 2007
    Location
    Tariffville, CT
    My Bikes
    Tsunami Bikes
    Posts
    11,784
    Mentioned
    9 Post(s)
    Tagged
    0 Thread(s)
    BMX'ers intentionally don't rock their bikes when accelerating from the gate. At low speeds (under 10-15 mph), apparently it's better to not rock since it's advantageous to transfer pedaling power into forward motion as quick as possible, even if you aren't as efficient or powerful.

    However, once they get going, they rock like anyone else. I guess ultimate power is better when rocking so it's better to increase power to max when going 30 odd mph in a tiny gear.

    I found this was true when doing standing start ~100m sprints on a road bike. I'd accelerate sort of vertical and rigid for 2-3 pedal strokes then get rocking as I shifted up in speed and gears.

    A shorter rider will rock their bike at steeper angles than a taller rider. The bars and seat move back and forth about the same amount for all riders, a little more for a taller rider, a little less for a shorter rider. This means the shorter rider rocks a lot relatively speaking and the taller one very little. Abdujaporov got a reputation for being a swervy sprinter but he simply rocked his bike appropriate for a sprinting 50-51 cm or so bike - his reputation might have been earned on what he did to get to the sprint position, the fact that he sprinted while looking down a bit too much, or that he tested positive a few times for a stimulant used by Soviet fighter pilots.

    Since a bicycle stays upright due to slight steering motions, it's much easier to stay upright when working hard by letting the bike swerve back and forth a bit. Rocking the bike allows this to happen naturally.

    At slower speeds (climbing), rocking the bike allows you to focus on pulling up hard since you can counter that force when rocking the bike. You can actually feel your hamstrings tensing up as you pull up if you're pedaling slowly.

    a rocker,
    cdr
    "...during the Lance years, being fit became the No. 1 thing. Totally the only thing. It’s a big part of what we do, but fitness is not the only thing. There’s skills, there’s tactics … there’s all kinds of stuff..." Tim Johnson

  9. #9
    Super Moderator
    Join Date
    Feb 2007
    Location
    Tariffville, CT
    My Bikes
    Tsunami Bikes
    Posts
    11,784
    Mentioned
    9 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by Compressed View Post
    Note also in the pic of the sprinters - if you draw a line straight down from their torso, it doesn't hit the tire where the tire meets the ground. When you rock the bike, the bike swerves, so the bike stays centered under the rider. The tires move laterally relative to the rider - the bike will seem to pivot at around the BB or so, maybe a bit higher (that's where the vertical line from the rider's centerpoint will intersect with the bike).

    Since it is less efficient to move the rider's body back and forth in a sprint (say 150 lbs rider), it's better to move the 15 lbs bike. So the bike gets tossed around (swerves) while the rider's torso goes in a reasonably straight line. His arms and legs are moving but not his torso, not too much anyway.

    Great pic btw.

    cdr
    "...during the Lance years, being fit became the No. 1 thing. Totally the only thing. It’s a big part of what we do, but fitness is not the only thing. There’s skills, there’s tactics … there’s all kinds of stuff..." Tim Johnson

  10. #10
    Senior Member
    Join Date
    Feb 2007
    Posts
    3,918
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Rule of thumb..


    The stem should always stay inside of the shoulders. Take that pic above and draw a line from the riders shoulders to the stem. it wont go "outside" this line.... ever.

  11. #11
    Senior Member Bullseye's Avatar
    Join Date
    Feb 2006
    Location
    Boulder, CO
    My Bikes
    Cannondale systemsix, Raleigh Competition '05
    Posts
    498
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by Compressed View Post
    That's exactly what I was referring to, good explanation. This is probably
    and
    http://www.youtube.com/watch?v=Ji_XcHvJvac
    you posted THE VIDEO! god, I love that vid.

    -bullseye

  12. #12
    Making a kilometer blurry waterrockets's Avatar
    Join Date
    May 2006
    Location
    Austin (near TX)
    My Bikes
    rkwaki's porn collection
    Posts
    25,598
    Mentioned
    13 Post(s)
    Tagged
    0 Thread(s)
    Yeah, that McEwan video is great.

    I downloaded it, transcoded it, split out a scene, and slowed it way down. Here's how you swing a bike in a sprint:
    http://www.youtube.com/watch?v=1-OOdToL01c

  13. #13
    Compressed
    Guest
    Quote Originally Posted by Bullseye View Post
    you posted THE VIDEO! god, I love that vid.

    Hell yeah!

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •