Aero gains: Myths & Maths.

We all know triathletes love a bit of bling. They can’t resist the new kit, gadget or fad. Equally, road cyclists love to roll their eyes at this phenomenon.

Not only do I notice an awful lot of money being spent on the flashy kit in the triathlon community, but I also get asked often what will actually make a difference on the bike with regards saving time and energy… and without breaking the bank.

My answer usually trips off the tongue pretty quickly… your position on the bike is BY FAR the highest priority and the best way to save time and energy but is also very cheap to achieve. After that – an aero helmet is also another inexpensive (relatively speaking) method to cut through the air better. Third on the list would be some deep dish wheels, bearing in mind it is the FRONT wheel that cuts through the air first!

Your position on the bike is easily corrected and enhanced with clip-on aero bars, and an investment in a full bike fit based upon your event. In other words, your position in a sprint distance triathlon can be very aggressive (i.e more uncomfortable), whereas your position for a full distance Ironman MUST put comfort first.

Returning to the topic of wheels… the track cycling community has been using deep dish and disc (spokeless and solid) wheels for decades. As I said, the most benefit you get from deep dish wheels would be to place one on the front of your bike, rather than the rear. Of course, we think this would look weird and not aesthetically pleasing (refer my very first sentence above!) The track cyclists have been using disc wheels on the front and rear for this very reason, however they don’t have wind to contend with, and the front wheel would become un-steerable for a triathlete or time-trialist on the open road.

With all this being said, you don’t have to take my word for it… have a look at the article below – it’s ten years old, but the science hasn’t really changed. Some eye-opening statistics which I am firmly aiming at those feeling pressure to buy a shiny new TT bike. I’ll guide you towards the bottom line of the table…. time trial tubing on an aero bicycle is the most expensive and least effective way to gain time and save energy.

Another opinion I enjoy sharing is to explain that there has to be a tipping point for testing this gear. The simplest way I can describe this is to point out that a human on a bicycle pushes air forward, in addition to trying to cut through it. Once these two variables have been balanced out, the sweet spot for aero measures to make the most difference is way over 40km/h (in this article, the rider was traveling at 50km/h!!). So… the further you get above and below this speed, the less effect these things have on your speed and energy saving.

Take a look at the top of the table… a skin suit will make the most difference, perhaps not obvious but human skin just ain’t designed to move quickly through the air (or water by the way)… a stonking 134 seconds improvement over 40km. So… without the chance to wear a complete cycling skin suit, a very snug-fitting tri suit with sleeves to the elbow (have a look at the elite line-up at Ironman events these days) will help. Then we arrive at aero bars, aero helmet, and body position. 

I love the tongue-in-cheek comment about adding an “amount you look more pro” column! which comes to the nub of the issue… I’ve experienced the feeling of running a super-light time trial bicycle out of T1 in races. It feels good, and boosts the confidence, and yes okay… you look smashing. So… if you can justify the spend, go for it!

My point however remains firm… please don’t feel pressured to go out and spend your hard-earned cash on a time trial bike if you just can’t justify the outlay. Yes your peers probably did just that, but don’t feel left out. (I raced a couple of events on a road bike with an aero helmet and really enjoyed the confused expressions from men on full time trial rigs as I sailed past!)

By way of advice… I have a few pet peevs in the swimming pool, and just a couple watching the bike portion of triathlons…. 

Please please please don’t get a time trial bike then spend most of the event sat up with your hands on the bull horn handlebars rather than tucked deep into the aero bars… you have now made your position about 30% less effective than being on a simple road bike while holding the drop bars!!!

Finally… and there’s no soft way to say this… consider the air being displaced by your body shape too.



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