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Aerodynamic efficiency, which minimizes air resistance on the leading edge of the bicycle, is essential in reducing energy expenditure and helping the rider gain time. Wind tunnel tests at Texas A&M have determined that the streamlined Vision Tech time trial bar reduces overall drag by 0.2 - 0.3 lbs., compared with a conventional aero bar/bullhorn setup. This reduction in drag can translate to up to a minute time difference in a 40K time trial. The extended use of airfoil shaped contouring and tubing throughout significantly decreases air turbulence.
The following chart lists projected times for a 40 km time trial based on wind tunnel tests at Texas A & M University on January 11, 1999
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PROJECTED TIME AND SPEED (MPH) FOR 40K DISTANCE
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WATTS PRODUCED BY RIDER >>
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250 WATTS
~ 22 MPH |
285 WATTS
~ 25 MPH |
390 WATTS
~ 28 MPH |
450 WATTS
~ 30 MPH |
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HANDLEBARS
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DRAG @
30 MPH
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MPH
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TIME
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MPH
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TIME
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MPH
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TIME
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MPH
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TIME
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Vision Aero
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.590
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23.03
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1:04:45
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25.23
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59:07
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28.36
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52.36
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29.88
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49:55
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Vision Tri-Max
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.685
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22.93
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1:05:01
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25.12
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59:23
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28.23
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52:50
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29.74
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50:08
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Profile X-Bar
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.704
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22.91
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1:05:05
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25.09
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59:26
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28.20
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52:53
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29.72
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50:11
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ITM Dual Aero
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.722
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22.90
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1:05:08
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25.07
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59:29
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28.18
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52:55
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29.69
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50:14
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Cinelli Angel Aero
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.759
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22.86
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1:05:14
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25.03
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59:35
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28.13
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53:01
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29.64
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50:19
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ITM Aero CX2
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.826
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22.79
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1:05:26
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24.95
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59:46
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28.04
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53:11
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29.55
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50:28
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Syntace Bullhorn/ Syntace C2
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.861
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22.76
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1:05:32
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24.92
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59:51
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28.00
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53:16
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29.50
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50:33
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Profile Bullhorn/Split Second
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.871
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22.75
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1:05:34
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24.90
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59:53
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27.99
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53:17
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29.49
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50:35
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Drop Bar/Split Second
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.929
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22.69
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1:05:44
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24.84
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1:00:02
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27.91
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53.26
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29.41
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50:43
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Aerodynamic Positioning:
To be in the best aerodynamic position, keep the
back as flat and low as possible without loosing power output and comfort.
It's best to use the Riser Kit to adjust the elbow pad height. The Riser Kit
also allows the air to flow over the wing and under the armrest plate with
the least disturbance.
Also See:
The Aerodynamic Facts
Aerodynamic Drag of Streamlined Handlebars 1995
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