ORIGINAL: found here
| Aerodynamics for Time Trial |
By Gary Tingley
I raced my first time trial five years ago at Fiesta Island. Coming from a purely cross-country mountain bike background, I assumed that racing and training for a time trial would be easy compared to training for MTB events. I quickly learned that the sport of time trial racing is very technical and it can take years to develop optimal fitness and the skills needed to excel in this discipline. In the following article, I will explain the finer points of time trial aerodynamics.
Aero Priorities … "What is most important?" - From what I have read, my time in the wind tunnel, and the various data that I have seen, I can make the following list of priorities for a time trial bicycle and the rider. These numbers are fully debatable and represent only my opinion. They were gained from various sources and in most cases represent a rider at 30MPH over a 40K course.
** Maximum time savings for these upgrades over 40K:
Maximum time savings for these upgrades over 40K:
Handlebars (Reference: J Cobb, Vision
Tech)
|
From: |
To: |
Savings: |
|
Drop Bars |
Integrated Aerobars |
2 - 4 Minutes |
|
Drops/clip-ons |
Integrated Aerobars |
15 secs - 1 Minute |
Clothing (Reference: Rainer Pivit)
|
From: |
To: |
Savings: |
|
Shorts & Jersey |
Skin Suit |
29 seconds |
|
--- |
Add Shoe Covers |
13 Seconds |
Wheels (Reference: J Cobb)
|
From: |
To: |
Savings: |
|
"Box Style" 32
spoke wheels |
Deep front/disc rear |
2 - 3 Minutes |
|
Deep front/rear |
Deep front/disc rear |
30 Seconds |
Frame (Reference:
J Cobb, Martin/Cervelo)
|
From: |
To: |
Savings: |
|
Round tubing |
Airfoil chainstays,
down/seat tube & post |
30 secs - 2 Minutes |
Fork (Reference: Oval Concepts, J
Cobb, D Bunce)
|
From: |
To: |
Savings: |
|
Round tube fork |
Oval Jetstream |
35 seconds |
|
Round tube fork |
Ouzo Pro Aero |
30 seconds |
|
Round tube fork |
Hotta |
30 seconds |
Helmet (Reference: J Cobb)
|
From: |
To: |
Savings: |
|
Standard road helmet |
L.G. Prologue |
30 seconds |
|
Standard road helmet |
Standard road helmet, tape
over vents |
10 - 30 seconds |
Aero Wheels - Using aero wheels (vs. 32 spoke box rim wheels) can
save you two minutes over a 40K time trial. The fastest wheels are a deep dish
front (Zipp 808, HED 3) paired with a disc rear (Zipp, Corima, Mavic, HED).
Aero wheels definitely make a substantial difference in reducing aerodynamic
drag. They can also increase your sail area helping to push you along.
Aerobars
- Aerobars are the #1 most important feature of any time trial bicycle.
Integrated one-piece aerobars are more aerodynamic than clip on bars. Wind
tunnel tests show that using aerobars can save 4 minutes over a 40K time trial
course. Currently there is an abundance of aerobars on the market, and the
fastest aerobars bear the labels of Profile Design, HED and Vision Tech. The
latter, HED and Vision Tech one-piece, are some of the best designed and likely
the most aerodynamic aerobars made today. For clip on aerobars, the classic
Syntace C2 (a triathlon favorite) has been moved aside by the new slippery
Vision Tech base bar and clip on bars.
Aero Frames - Many frames on the market claim to be aero. The most important
feature that a frame can offer you is the fit, followed by performance and
comfort, and UCI rules if racing national championship events. Frame
aerodynamics are likely one of the least important features on a time trial
bicycle. When selecting a frame, fit and comfort are priorities. How do you
know if a frame is aero? Start with the tubeshapes of the bicycle. Are the
tubes foil shaped? Is the downtube narrow and deep? Is there a rear wheel
cut-out? Seatpost? These are some items to consider. Some companies that
produce aero time trial frames are (in no particular order) Trek, Litespeed,
Cervelo, Yaqui, Javelin, Kestrel, Felt,
Softride, Corima, Lotus, Elite, Quintana Roo, Aegis, Pinarello and Colnago.
Conclusion – Aerodynamic gear does not come cheap, so there are
three things to consider when upgrading your equipment:
- Buy the fastest gear you can afford, but
remember that position on the bike is paramount to anything you bolt onto
it
- Buy an aero helmet first, then a skinsuit, then
wheels
- The front wheel is more important than the rear
in terms of aerodynamics
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