Many new to the sport will hear about triathlon bikes which is normally followed by the question “What is a triathlon bike?”
These are very specialised bits of kit which are designed with one thing in mind, raw speed. In nearly every triathlon, you cannot ride directly behind another rider, and must leave a gap of 12 metres. This is as sitting behind another rider can save up to 50% energy relative to riding solo, giving the rider behind a significant advantage, as they will be fresher for the run.
As a result, triathlon bikes are build to be as aerodynamic as possible, to help you cut through the air as efficiently as possible.
Introduction to aerodynamics.
Most of you will be familiar with formula one cars, which have all sorts of wings and panels on them to improve their ability to cut through the air. When travelling at low speed, aerodynamics have very little impact, but the faster you go, the harder it gets to punch a hole in the air.
Most people could ride a bike at 10MPH, this is not especially difficult or challenging. Even the old boy that lives near you and rides their squeaky bike to the shops can probably hit 10MPH with a bit of effort. However, hitting 20MPH is a LOT more difficult, as the air provides progressively more resistance the faster you go.
Like formula one cars, we can make ourselves faster by becoming more aerodynamic. On bicycles we do this by making ourselves as low and narrow as possible. This way we present the smallest possible shape to the air, allowing us to punch a smaller hole in the air, requiring less effort.
Think of a triathlon bike as being the opposite of a city commuting bike. Many bikes you can buy, or hire are designed to help people cut through traffic and get to work. They place you in a bolt upright position, with the handlebars notably higher than the saddle. This is a very slow, inefficient way to cycle, but speed is not a concern for these riders, they just want to get home.
On the flip side, a triathlon bike is (fairly) uncomfortable. This isn’t to say that you can’t get comfortable on them with the right setup, but it will require a lot of work. If riding in the time trial position was inherently comfortable, safe and fast, everyone would be riding around on these bikes.
How triathlon bikes make us more aero
The most aerodynamic part of the rig will always be the bike itself. It’s narrow, and triathlon bikes are shaped in a way that optimises airflow around it, rather than having rounded tubes found on road bikes.
What is less aerodynamic is the thing sat on top of the bike, you. The rider creates infinitely more drag than the bike ever will, so we need to find ways to reduce the drag the rider creates.
We can wear aero triathlon suits, aero helmets and other gadgets such as shoe covers, but the position our body is in on the bike makes a much bigger difference than the bike itself. In fact, in most cases the rider creates 90% of the drag, while the bike is only responsible for 10%.
There are two riding position on a triathlon bike, on the aero bars (or “the bars”) or on the bullhorns (also known as “the horns”), which is a term used to refer to the handlebars.
We should be spending 95% plus of our race on the aero bars, only coming onto the bullhorns for braking, climbing or sharp corners.
When on the bars, our body position is low and narrow. How low and how narrow you get depends massively on your setup. Triathlon bikes are very adjustable, allowing you to move the bars, pads, saddle and many more components around to get comfortable. The difficulty is in balancing aero with comfort. We can have the most aerodynamic position possible, but if we can only hold it for ten minutes without back pain, is it really going to be the right position to ride 180KM during an IRONMAN?
We not only have to think about comfort, but also efficiency. Being as low and narrow as possible isn’t always fast either. If our whole body is contorted to the point we can’t get enough air in or our hips are restricted, we are both slower and more uncomfortable then we would be on a road bike.
Do you need a triathlon bike?
The answer to this is a big old no. In fact, if you had no idea what a triathlon bike was when you opened this article, if is definitely a no. They are expensive, difficult to ride and generally only for seasoned triathletes looking for that extra edge. I have recorded a podcast episode you can find below that will help someone understand when the right time is to step up to a triathlon bike. Take a listen, and subscribe if you find it useful.
In fact, even if someone owns a triathlon bike, it may not be the right choice in every race. Remember when I said that you should be spending 95% of your time in the aero position? Well what if we’re taking on a very hilly triathlon? Tri bikes are not only heavier, they also don’t handle as well on the descents, so we could be giving away a lot of time on the hills. In the vast majority of races you will make up any time lost by going so much faster on the flats, but there are certain events which include so many corners and hills that you may struggle to really get up to speed on a triathlon bike before you’re starting to slow down again. I have spent many races on my triathlon bike pulling away from the competition on the flat, only for them to pass me in the twisty or hilly sections.
If a time comes when you are looking to upgrade to a triathlon bike, don’t get drawn into the marketing. Remember how we talked about a bike frame being responsible for only 10% of the drag? Well if a bike is advertised as being 5% faster than last year’s model, that’s only a 0.5% reduction in drag, which will be worth well under a minute at most IRONMAN events. If you want to win the world championship then this is going to be essential (you’re probably getting the bike for free anyway), but if you’re just trying to get round, you would be much better off buying a cheaper bike and hiring a coach instead, which can take hours, not seconds off your time.
What about clip on aero bars?
A set of clip on aero bars offers you the best of both worlds. Bolted onto your handlebars (by a mechanic or with a torque wrench), these allow you to get into that nice low, narrow position without buying a new bike. So why do triathlon bikes event exist, if you can achieve the same results for £40?
Well, when using a pair of clip on aero bars you won’t have access to your gears. On a triathlon bike you will be able to change gears when in aero, while this will not be possible on a road bike with clip on bars, unless you spend the money to buy new shifters and wire them into the bars.
The result of this is needing to reach back to your shifters every time you need to change gear, which can get frustrating. You also need to shift your saddle slightly forward to get comfortable, which makes riding in the road position less comfortable.
Riding with clip on aero bars is definitely a compromise, but costs an absolute fraction of a triathlon bike, so I recommend all athletes try racing with them before investing in a full triathlon bike.
Conclusion
Triathlon bikes are the fastest bike out there, but are overkill for every triathlete in their first year of competition. I would recommend any competitive triathlete looks at upgrading to a triathlon bike at some point, but make sure you can actually afford it before you blow money you don’t have.
