Aerodynamics: Victory by a Thousand Cuts

(C) Copyright 2011 John Mott

Jordan Rapp, a 2x 3x 5x Ironman Champion meticulous about aero details | Photo By Eric Wynn


Some say that aerodynamic tricks are silly, and they're right (at least partly). There's no single aerodynamic gimmick on the market, no single tweak you can do with your cable routing or spare kit configuration that will move you up from the back of the pack to the front, or even from the middle of the pack to the front. Given this fact, some conclude that rather than spending time thinking about bike setup, one should spend that time training instead. Not bad advice, since training more is a sure way to get faster for most of us, but it does overlook an important fact – when you cut a few seconds here and a few more there, and add up that time savings over dozens of little improvements, you can end up with a huge improvement. And don't let anyone tell you that you have to be going a certain speed for aerodynamic improvements to help – since slower riders spend more time on the course, they actually save more time at a given distance (even though they save less drag).

So details matter, but there are significant challenges in wading through various marketing claims and deciding on the best options for bike gear and position. Marketing claims are often complete fabrications, fast positions are often uncomfortable ones, and the best gear is sometimes prohibitively expensive. ATC would like to help by giving you our top ten aero tips, many of which will not cost you a penny. So here they are, listed in approximate order of "Bang For The Buck."

1. Position: Get yourself in a comfortable, powerful, aerodynamic position. The best place to start is to read up on F.I.S.T. positions. This philosophy of fitting is an industry standard used by pro cyclists and triathletes alike. (ATC offers F.I.S.T Certified Fits.) It may be that your current bike doesn't have the head tube or seat tube angle necessary to achieve your best position, which is where having a tri-specific frame is a big help (see tip #2). While you want to try and get as aerodynamic as possible, your position must also remain comfortable enough to not distract you from the real goal – any serious pain should be suffered in your legs (that is, in pedaling faster). It's worth taking the time to figure out how to get yourself aerodynamic and comfortable, because potentially minutes of time are on the table. Unless you need a new frame, this will cost you very little money, but it may take a lot of experimenting with small adjustments to make a fast position work for you.

2. Frame: A good tri frame will provide two things: minimal aerodynamic drag and support for a good aerodynamic position. Once you know what your ideal position is, you'll want to find a frame that can support that position. A professional fit can help recommend frames and sizes that will work for you, or you can read up on stack and reach and figure it out for yourself. Ideally you want a frame that will fit your position with as few spacers as possible, and a normal length stem (70 to 120mm). It's better to have a nice aerodynamic shaped head tube than round spacers sticking into the wind! (And safer, too.) Good tri frames will also hide cables inside the frame, feature aerodynamic tube shapes wherever possible, shield the rear wheel from the wind, and provide a steep seat tube angle that allows you to get the front of your body low while keeping your hip angle open for power.

Beware of frames that only look aerodynamic. Stick with brands with a proven track record of wind tunnel development like Cervelo and Cannondale. Generic frames are often solid bikes that look great, but they rarely are truly aerodynamic.

3.Remove Clutter: This is a freebie! It's common to see people with multiple water bottles and large contraptions to hold spares and food at sprint and Olympic distance triathlons. The truth will set you free – in a sprint you probably don't need any water bottles, and you usually need only one bottle for Olympic distances. Since longer races have hand-ups, you can often get by with just one or two bottles even for half and full Ironman races. So in short, don't haul around gallons of water that you're not going to use, but be sure to try these strategies out in training so you can be confident and comfortable with them. Also, keep your spare kit as compact and simple as possible. Don't think that just because you have spares and bottles behind your seat that the wind isn't hitting them. It probably is! Inexpensive aerodynamic water bottle placement options abound. One of the best, and simplest, is to mount a cage between your aero bars with zip ties. This setup was used by Macca while winning the 2010 Ironman Championship with an aggressive attack on the bike leg. Others prefer the larger Profile AeroDrink style setups with a straw. Be sure to cut that straw short, though – round shapes are among the least aerodynamic possible. ATC stocks a wide selection of bottles and cages you can try.

Race numbers are sometimes provided as large pieces of paper. You can attach these in an airfoil shape around the seat tube with a bit of tape. (This way if you don't already have an aero seat post, now you do!) Also you do not have to wear your race number during the bike leg of most triathlons. Get yourself a race number belt and leave it in transition until the run so it isn't flapping around in the wind while you bike. WTC/Ironman brand races do require you wear the number however.

4. Tires and Tubes: There's a great tragedy in the world of triathlon and bike racing, and it occurs all too often. A cyclist will spend $2000+ on a set of fancy race wheels, and then put a slow tire on them. The result is sometimes a race wheel setup that is slower than the person's training wheels! Two things make a tire fast: rolling resistance and width. It doesn't matter much if you go with clincher or tubular, since they perform similarly when you use the same level of tire. Use the free rolling resistance chart provided by biketechreview.com to get an idea of what tires are fast. ATC stocks some great ones like the Vittoria EVO CX 320tpi and Continental GP4000s (Recent findings from many sources indicate the 4000S has excellent aerodynamics as well as rolling resistance). If you use clinchers, pick up some latex tubes for a little extra rolling resistance improvement (and don't worry, the fast tubular tires have latex in them already). Latex tubes can be hard to find at most bike shops, but ATC always has some in stock. The good news is as you upgrade to these faster tires and tubes, you are also getting more comfortable tires and tubes! The downside is often shorter life and less puncture resistance, so save your premium tires for race day (and maybe the ATC Saturday Ride).

Tire width also plays a role in speed – the narrower a tire is, the less aerodynamic drag you will get. This is especially important up front, where the tire is not shielded by the frame at all. A good compromise for time trials is to use a narrow (19-21mm) tire up front and a normal (23mm) tire in the rear. You'll get the benefit of increased comfort and flat resistance on the rear tire, and optimum aerodynamics up front where it matters most. For road races and crits, stick with 23mm all around for better cornering stability. The author, being an aero weenie, tried a 19mm front tire in a crit once....once.

5. Aero Helmet: These are relatively cheap for the drag savings they offer. You'll want to pick the smallest size that fits comfortably, and the tail of the helmet should lay flat against your back when in your aero bars. Helmets with vents offer extra cooling on hot days, but those vents also slow the helmet down a bit. You can always tape the vents over on cold days, though. Don't worry if you tend to ride with your head down a lot. Aero helmets are faster than road helmets even when the tail is sticking up in the air.

6. Clothing: Another cheap way to go quicker – make sure your clothes don't flap around. A fancy skin suit would be ideal, but any tight-fitting clothing will work. (Some have even been known to just borrow their wife's shirts for a snug fit!) Consider avoiding gloves – it seems crazy but since they're up at the front of the bike there's a measurable drag increase from wearing them. Those looking to split aerodynamic hairs should look for suits without pockets if they don't need them. If you plan to do bike races or time trials, be sure the suit has sleeves, as sleeves are required at most cycling events. (Update: as of 2011, USAC cycling events no longer require sleeves for time trials)

If you do bike racing events, numbers are often provided that must be attached to your jersey. While it is required that you use at least four safety pins to secure it, you can also use 3M spray glue to keep it tightly attached to your jersey instead of flapping in the wind.

7. Aero Wheels Aero wheels look super cool, and they do work, but they are expensive. A disc wheel in the rear is almost always the fastest option, even on hilly courses. If you can’t face the price tag you can always get a wheel cover from wheelbuilder.com. Despite being a bit heavier, they are just as fast aerodynamically. For front wheels the best choices are deep rims from HED and Zipp, as they have patented rim shapes that outperform most generic wheels. Other brands, such as SRAM, license Zipp rims and can be a better value at the expense of a bit of extra weight (which, trust us, does not matter as much as people claim). The deeper the better as long as you can handle them in crosswinds. If you aren't sure how deep of a rim is right for you, feel free to drop by ATC and ask about a demo set to try. And don't be afraid to run a disc in the rear. Since the rear wheel doesn't turn and steer you, most find that they are no problem to handle at all.

8. Front End: The front of the bike hits undisturbed air and is the most important part to improve aerodynamically. Be sure that your aero bars, fork, and brake levers have nice aero shapes and minimal size. A good rule of thumb is to go with the narrowest aero bar option available, since any extra width would just be extra frontal area. (And you shouldn't be touching that basebar much anyway.) Vision makes a great line of very affordable aero bars that are also among the most aerodynamic. Those looking for the ultimate might step up to the 3T Ventus, or 3T’s uci legal options if you plan to go to some big-time bike races. For brake levers the Vision aero brake levers are incredibly aero and light, and not too expensive, so are a good choice as long as you can handle grabbing the sharp edges.

Forks are probably the single most important bike component aerodynamically. 3T makes a great line of aerodynamic forks with their Funda series, and most good TT frames like Cervelo P1/2/3/4 and Cannondale Slice come with great aero forks from the factory.

9. Cable/Wire Routing: Another freebie! Make sure your cables are not any longer than they need to be, and keep them nice and tidy. Sometimes a zip tie to make things orderly can be a help. If you have an aerodynamic shaped frame, run wires for computers and power meters along the trailing edges of tubes, not the leading edges.

10. Chainrings: A minor detail but easy to install and pretty cheap. Aerodynamic chainrings can save as much as six seconds per 40k. Once your current chainring wears out, you might as well try an aero one.

We hope these tips help to improve your races this season, but don't forget to train! Also, feel free to comment with your own aero tips.