1. How much power you can produce

2. Wind resistance. The faster you go, the more wind drag you need to overcome.

A few months ago there was an excellent article in Velonews (Vol 39, No 3) about which aerodynamic equipment benefits most during an individual time trial. What they didn't do is rank the cost vs. benefit for each piece of equipment and the associated time savings. Years ago I saw something like this done by cyclingnews and found it extremely interesting. Unfortunately it's buried deep in the internet and is lost forever so I thought I'd rehash it for those of you who missed it.

The following chart shows the aerodynamic savings according to what www.aerosportsresearch.com calculated for Velonews (I bascially copied the photo above and the chart chart below and added in the approximate costs for each equipment piece).

A couple notes:

- These numbers are calculated for a rider over 40kms at a time of 48minutes. Faster than most of us could go!

- I don't understand the rational of some of their wheel comparisons and why they didn't calculate the difference between a standard rear wheel and a rear disc wheel. I tried calculating the numbers myself but couldn't get them consistent with the numbers in the chart. In any case, this illustrates the point of the cost-benefit analysis.

Biggest Bang For Your Buck?

1. Using aerobars that allow you to get into a tuck position will be the cheapest thing you can do for the aerodynamic benefit. You can get a set of aerobars for $200 and they'll save you a couple minutes in a 40km TT.

2. Getting a skinsuit will provide massive benefits. The only disclaimer is that the testing shown here was done on a specially designed skinsuit for Nike, not a standard skinsuit. I'm sure this skinsuit costs in excess of $1000, but you'll realize large gains with a standard skinsuit as well. The chart above shows an extreme comparison between this Nike skinsuit and regular jersey/knicks in windtunnel testing.

3. Shoe Covers will cost you no more than $50 and could save you half a minute in 40kms. Shoe covers smooth turbulent air over the straps and buckles of the shoes.

4. Upgrading from a regular helmet to an aero helmet could save you over a minute for a $200 spend.

5. Time Trial Wheels are getting into the expensive end of TT equipment spectrum, but they do provide some good time savings and look very PRO. Having an aero front wheel will make the most significant difference and will cost the least of the two. Most of you probably already have a set of deep dish aero wheels for racing anyway. A rear disc wheel is one of the last items you should spend lots of money on if you're looking for big savings. However, if you want to look cool this should be the first item on your list ;-) A good analysis of different wheel types vs drag in different wind conditions can be found on the HED website.