In non-drafting triathlon, cycling is all about getting as aerodynamic as possible. Pro cycling legend turned bike designer Chris Boardman told triradar.com how to avoid some of the pitfalls of choosing an aero set-up.
Chris Boardman’s cycling career included an Olympic Gold medal, numerous world records and Tour de France stage wins. He’s been associated with cutting-edge bike design since riding his famous Lotus bike at the 1992 Barcelona Olympics, and now advises the Team GB’s cyclists as well as working on new bikes for his brand, Boardman Bikes, who launched their 2011 range last month, and count some of the world’s top triathletes among their riders including Alistair and Jonathan Brownlee, Hollie Avil and Pete Jacobs.
There are situations where a straight-line aero frame will work against you. I probably spend more time in a wind tunnel than anybody, we get to spend literally a week a month in a wind tunnel, and you can make some lovely shapes that perform beautifully in straight-on flow, but the penalty is when you start to move off that you get hit really hard, because straight flow is fairly sharp shapes and as soon as you go slightly off that sharp edge turns the air turbulent really quickly and the tubes will suck you backwards, so you really don’t want that. Most of the profiles people use are based on aeroplanes, going orders of magnitude faster in relatively clean air and it just doesn’t work. We operate at horrible speeds, 50kph, and it’s a different aerodynamic challenge, so it’s got to be a different shape.
The rider interferes with the frame a lot. The inside and outside of tubes are different [on some of Boardman’s new models], it’s quite a small effect, but there is an effect, you want the air to push round the outside really, so you tune the tube shape to make it do that, and make it relatively flat on the inside.
Light riders [who are more affected by crosswinds] should still go for aero shapes, I don’t think you’ll feel crosswinds in the frame, but you’ll feel it in the wheels. I’d really think about your wheels. I’d go for a really low profile shape, particularly on the front.
Changing something on a bike frame to alter its aerodynamics is like hitting snooker ball that hits a load of other balls, very quickly it gets so messy that it’s really hard to follow and we’re still picking that apart. I work with [Formula One team] McClaren a bit and I spoke to one of the engineers, a guy called Paddy Lowe, and we were sitting on a balcony looking at all the Formula One cars that come out every year, and I said ‘how do you manage to keep making it better every year?’ and he said ‘well back there is roughly where I came in’, pointing at a car, ‘and I remember producing it and thinking oh crap, we just can’t do any better than that, and the next year we did, and the year after that we did,’ so you’ve just got to have faith that you will. It’s probably for diminishing returns, but we already know things we want to do differently for 2013.
I see pointless features on bikes all the time. And some of it doesn’t do any harm, it’s for marketing reasons and you’ve got to stand out from the crowd but, with a lot of this stuff, people should ask more questions. Say why have you done that, why is that tube curved, why have you made kinks in the forks, people should ask those questions, because if you’re genuinely interested in performance and the person who’s selling you that bike is telling you it will improve performance they should be able to answer.
People often focus on the wrong area. It’s a holistic package and needs to be treated as such. The bike is part of that, but just one part of it, so people need to look at the holistic package and not a lot of people do that. I think a lot of the time they do know, but they don’t want to go there.
I love light bikes and I love picking up our Elite SLR 9.4. I can’t help it! But if I had to go out and buy a bike I’d buy one of the aero frames.
There’s hardly anything in it now in terms of weight, between the aero frames and the ‘light’ frames. I’ve got one of these [AiR aero road] frames, kitted up with SRAM Red and light wheels, and it’s bang-on the legal weight limit. I get to have my cake and eat it. So you can do that, but people just want to go mega, mega light.
You have to put the rider weight and the bike weight together so you’ve got an 80 kilogram package, and what’s 200g as a percentage of that, and then you look at what’s weight as a percentage of performance, 20 per cent, then you’re down to 0.004 or something. It’s about perspective.