Speed and Aerodynamic Ride Position

Discussion in 'The Bike Cafe' started by poky, Sep 15, 2006.

  1. poky

    poky New Member

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    Assuming there is no ambient wind, at what speed should you use the drops? Similarily, if you have a tail wind is it beneficial to not use drops?
     
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  2. Glenfiddich_Man

    Glenfiddich_Man New Member

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    The way I think of it is the tailwind is not usually going to be over the speed you will be travelling. So you never the less will be heading into wind in a way. I ride a Tri bike and a road bike, and it just comes natural to get low, so that's what i usually do. Its pretty much dependant on what you are after, if you want to improve your times, get down.
     
  3. Powerful Pete

    Powerful Pete New Member

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    Your main problem is aerodynamic drag, especially as you begin to pick up speed, so it is always a good idea to stay as low as you can ride comfortably.
     
  4. hoodoo40

    hoodoo40 New Member

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    I'm no speedster, more of a long commuter. I do try to stay low most of the time. I especially make sure I stay low if at 15 mph or over.
     
  5. Eastway82

    Eastway82 New Member

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    It's exponential - the faster you go, the more difference the drag makes. If you want to prove it to yourself, find a long downhill, start off sitting up like a sail, and see how the speedo ramps up as you get lower and more efficient. Just don't forget to watch the road as well...
     
  6. e0richt

    e0richt New Member

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    ok, aerodynamic position is important, but last weekend, I was out on a group ride. I ride on the hoods and there were times where I felt like I was working pretty hard for the speed that I was getting. Well for some reason, I became aware of my form on the bike, I put my knees closer together, tried to have an "idealized" pedal stroke but was still riding on the hoods. It was interesting to note that I was able to catch up and keep up with the other riders. Now Im just a 15-21 mph type of rider and I am significantly overweight (but getting smaller...). I thought how interesting it was that just a little awareness of body position, in terms of pedalling motion, was able to make a big difference.
     
  7. carpediemracing

    carpediemracing New Member

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    if you have a relatively good position, your torso position may not change from the hoods to the drops. in fact, you may be more aero on the hoods. there was a test done a long time ago on pros and it found many pros more aero on the hoods - they concluded that this is because there is less forearm exposed to the wind on the hoods vs the drops. for a while pros were allowed to use the spinaci type bars (essentially mini aero bars) which put the racer's arms at hood/top level. they were wicked fast but were eventually banned. anyway, lower is not necessarily better - it's more a function of your whole body, not just where your hands go.

    I go to the drops for the following reasons:
    1. different position to use different muscles
    2. anytime I think there may be something unusual happening in front of me which would require corrective action - long/unknown/ or bumpy descent, blind corner, riding in a group of relatively inexperienced riders. being on the drops will give you, if fitted properly, the most control over your bike.
    3. sprinting or any super hard explosive effort.

    if you're in a group, keep in mind that drafting will help you much more than a slightly more aero position on the bike. in fact, I use the time I have when drafting to do things like stand up and stretch, drink water, etc. I find that when in a group you're comfortable with, hoods (or even tops) works fine.

    wind adds up so you may be going only 15 mph but if you have a 20 mph headwind, being more aero will help (or drafting). from my own experience, the tailwind has to be about 2x your actual speed to sit up and "sail". I rarely encounter 40-50 mph tailwinds so rarely get the opportunity to do that.
     
  8. HenryLaRoy

    HenryLaRoy New Member

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    I'm told that above 20 mph, wind resistance robs you of more energy than anything else.
     
  9. OldSoldier

    OldSoldier New Member

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    That's subjective. Up to 20 MPH the drag caused by bike weight (body weight and carry on baggage) as well as rolling resitance is probabaly the primary cause of resistance that causes expenture of energy. By the time you hit roughly 20 MPH, wind resistance is probably the primary cause of resistance. But the two aren't independant. They are additive. So...when you are riding with a tail wind the only resistance you are experiencing is bike weight and rolling resistance aided by the tail wind up until you achieve the same speed as the tail wind. After you are going faster than the tail wind, the wind resistance starts becoming a factor. It's not until you are going approx. 20 MPH faster than the tail wind that your actual speed becomes the dominate factor in resistance that robs you of energy. Dominate doesn't mean that the the original resistance is no longer present. You are still overcoming the resistance caused by bike weight and rolling resistance. Just because one becomes the primary cause of resistance doesn't eliminate the physics of the other.
     
  10. ebola

    ebola New Member

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  11. daniels

    daniels New Member

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    Remember though, there is only resistance due to bike weight when you are going uphill.
     
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