It has been discussed quite a bit on this board on where to improve your aerodynamics. I was unable to participate in last week's discussion (due to a sick computer), so here's my list:
1) Body position, namely achieved by aerobars. If you don't get the body position, there's no point in any of the other aero things to do. Proper fit by a professional (or by following the fit pages of Slowtwitch) will optimise this.
2) Aero front wheel. This is where the wind hits it first, no question. I would emphasise the number of spokes, rather than how deep a section (as the less deep it is, the easier to handle and is a lot more stable). Heck,sometimes I wonder about whether or not the old days of when we would skip spokes on a semi-aero section wheel produced just as fast results as now that we have to have the 46-56mm deep wheels. This is, before the days of wattage testing (so I can't quantify the numbers here).
3) Rear disc. Pick a disc, any disc, as long as the bearings are smooth. This also is something that has been proven fast. I would almost go so far to say that it should be purchased with the front, as it is just as important as the front wheel. And in these days of highly affordable, high-quality disc wheels go (yes, I mean the Renn disc), one could get a decent set of wheels for racing for about five C-notes.
4) Clothing. This sounds silly, but loose clothing will make you slow. You don't have to have the latest, wowie neato cool expensive tri suit to realise this. Your clothes should not flap in the wind. I remember an old article in a Road Bike Action where it showed that an unzipped jersey costs you a few watts and drag coefficient points. Sloppy-fitting singlets and run shorts would probaby cost you more than an unzipped jersey (from my guess).
5) Floppy things from your head, frame and other things that cause parasitic drag. Cobb found that Fignon's pony tail (amongst other things, like lack of aerobars, etc.) cost him that oh-so famous TT in some French race against a Yank who won some Tour by eight seconds. Hmmm. What about a flapping helmet strap, an STI cable, a Bento Box, an unpinned race number, an ill-routed cable? You get the idea. This is probably the lowest cost improvement you can make to your bike. I could add to this to get a Bartol System, as it gets rid of the front mech without getting rid of the gears. It does get rid of a front changer, a cable, and the shifter, rendering the bike more mechanically simpler if not more aero. Also, cover the valve holes on your composite wheels- this is something that costs pennies, but is definitely more aero.
4) Aero helmet. Sure it's hot, but it is again one of those things that help smooth the airflow. The Louis Garneau has not been tunnel-tested that I know of, but it shares a similar concept to the shapes that have been proven to win. I like the visor version of the helmet with a pair of low-profile glasses, like the Briko Jumper.
5) Aero frame. This is the next step after you have covered all of the other things in making yourself more aero. Sure, guys have done great, fast rides on round tubes, but the reasons are two-fold: they are gifted, and their body position is perfect or near-perfect. The Aero frame is worthless if your body position is not good. The aero frame is worthless if you're on a set of 32 spoke, box-section rims. The aero frame is also worthless if you're running STI, or have a bunch of items flapping all about, or your pony tail is flapping in the wind.
The whole point is to make yourself as invisible to the wind as possible. In the end, a rider is what makes the bike unaero. Once the body position is ironed out, the wheels and everything else just enhances the good body position.
1) Body position, namely achieved by aerobars. If you don't get the body position, there's no point in any of the other aero things to do. Proper fit by a professional (or by following the fit pages of Slowtwitch) will optimise this.
2) Aero front wheel. This is where the wind hits it first, no question. I would emphasise the number of spokes, rather than how deep a section (as the less deep it is, the easier to handle and is a lot more stable). Heck,sometimes I wonder about whether or not the old days of when we would skip spokes on a semi-aero section wheel produced just as fast results as now that we have to have the 46-56mm deep wheels. This is, before the days of wattage testing (so I can't quantify the numbers here).
3) Rear disc. Pick a disc, any disc, as long as the bearings are smooth. This also is something that has been proven fast. I would almost go so far to say that it should be purchased with the front, as it is just as important as the front wheel. And in these days of highly affordable, high-quality disc wheels go (yes, I mean the Renn disc), one could get a decent set of wheels for racing for about five C-notes.
4) Clothing. This sounds silly, but loose clothing will make you slow. You don't have to have the latest, wowie neato cool expensive tri suit to realise this. Your clothes should not flap in the wind. I remember an old article in a Road Bike Action where it showed that an unzipped jersey costs you a few watts and drag coefficient points. Sloppy-fitting singlets and run shorts would probaby cost you more than an unzipped jersey (from my guess).
5) Floppy things from your head, frame and other things that cause parasitic drag. Cobb found that Fignon's pony tail (amongst other things, like lack of aerobars, etc.) cost him that oh-so famous TT in some French race against a Yank who won some Tour by eight seconds. Hmmm. What about a flapping helmet strap, an STI cable, a Bento Box, an unpinned race number, an ill-routed cable? You get the idea. This is probably the lowest cost improvement you can make to your bike. I could add to this to get a Bartol System, as it gets rid of the front mech without getting rid of the gears. It does get rid of a front changer, a cable, and the shifter, rendering the bike more mechanically simpler if not more aero. Also, cover the valve holes on your composite wheels- this is something that costs pennies, but is definitely more aero.
4) Aero helmet. Sure it's hot, but it is again one of those things that help smooth the airflow. The Louis Garneau has not been tunnel-tested that I know of, but it shares a similar concept to the shapes that have been proven to win. I like the visor version of the helmet with a pair of low-profile glasses, like the Briko Jumper.
5) Aero frame. This is the next step after you have covered all of the other things in making yourself more aero. Sure, guys have done great, fast rides on round tubes, but the reasons are two-fold: they are gifted, and their body position is perfect or near-perfect. The Aero frame is worthless if your body position is not good. The aero frame is worthless if you're on a set of 32 spoke, box-section rims. The aero frame is also worthless if you're running STI, or have a bunch of items flapping all about, or your pony tail is flapping in the wind.
The whole point is to make yourself as invisible to the wind as possible. In the end, a rider is what makes the bike unaero. Once the body position is ironed out, the wheels and everything else just enhances the good body position.