The speed you can achieve on your bike is determined by two factors:
- How much power you can produce
- 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.
The following chart shows the aerodynamic savings according to what www.aerosportsresearch.com calculated for Velonews.
A couple notes:
- These numbers are calculated for a rider over 40kms at a time of 48minutes, a bit faster than most of us could hope to go.
- The wheel comparisons are curious and I'm confused why they are not consistent (ex: why aren't both front/rear "from" the box rims, and "to" a tri-spoke?). I'm also surprised that a tri spoke rear is measured as faster than a disc. I don't dispute it; my understanding has been that nothing is faster than a disc for the rear wheel.
Biggest Bang For Your Buck?
- 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. To make this even more cost-effective, you can pick up a pair of gently used bars on eBay for half that.
- Getting a skinsuit will provide massive benefits. The key here is that the skinsuit needs to fit like a second skin (hence, the name). You're not going for comfort; you're going for function.
- 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. You could even buy an oversized pair of thin athletic socks, cut holes for your cleats and pull them over your shoes for about $12.
- Upgrading from a regular helmet to an aero helmet could save you over a minute for a $200 spend. Again, searching eBay for a gently-used helmet can help you save significant funds. Remember, aero helmets aren't worn as often as regular road helmets.
- 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 because the front wheel is part of your frontal profile that slices through the air and wind resistance. And the front wheel will cost less than a rear wheel. My suggestion here is to opt for dual 80-100mm wheels. The more aero the front wheel, the better. And an aero rear is typically less expensive than a full disc wheel; though a disc wheel looks bad ass and sounds intimidating as you roll up to and past the competition!
The punch line here is that we are conditioned to believe we have to take out a second mortgage on our homes in order to ride faster. In reality, the most bang for the buck comes from the least expensive pieces of aero equipment. If you need to be cost-conscious, better to purchase a pair of shoe covers, a skinsuit, aerobars and an aero helmet than spend the same amount of money on just an aero front wheel.