Profile of Ernst Pfeiffer
Ernst Pfeiffer is an old hand when it comes to wind tunnel measurements. After working for aircraft manufacturer Dornier in Immenstaad on Lake Constance for many years, the 60-year-old graduate engineer founded the Gesellschaft für Strömungsmesstechnik (GST) with two colleagues in 1994. He has been running the wind tunnel himself for almost 13 years and, in addition to measurements for the aerospace industry, also carries out aerodynamic tests for the bicycle industry. In co-operation with TOUR, Pfeiffer developed a measurement method that still sets the global standard today.
Interview with Ernst Pfeiffer
The interview was conducted by Julian Schultz
TOUR: Mr Pfeiffer, which road bike do you actually ride?
Ernst Pfeiffer: (laughs) To be honest, I have nothing to do with racing bikes.
TOUR: We thought you were riding one of the fastest road bikes thanks to your expertise in aerodynamics ...
Pfeiffer: No. I've never ridden a bike as a sport. I came into contact with cycling as a television viewer during the heyday of Team Telekom. I already knew back then that cyclists also went into the wind tunnel when we built the test rig. But I didn't expect it to become such a hype.
TOUR: Together with TOUR, you have been carrying out aerodynamic measurements of racing bikes in your wind tunnel in Immenstaad for ten years now. How did this come about?
Pfeiffer: During the economic crisis in 2008, the GST (Society for Flow Measurement Technology, editor's note) and I thought about a new area of business. At the time, I wasn't focussing on individual racing bikes, but on the riders in combination with the racing bike. I then built a bike test stand and placed an advert under the heading "Bike in the wind tunnel". A few people got in touch - including Robert Kühnen (TOUR test engineer, editor's note). Shortly after the Eurobike in Friedrichshafen, we took our first measurements together - and got talking shop. When Robert left, he said: "Now I've seen how to do it well."
TOUR: Not only TOUR recognised the advantages of your facility. Numerous manufacturers such as Canyon and Giant have also been testing at your centre for some time now, and renowned triathletes such as multiple Ironman champion Jan Frodeno have also been guests.
Pfeiffer: That makes me a little proud. My customers appreciate that the GST wind tunnel sets the standard in Europe. They get very accurate and reproducible results here. I have TOUR to thank for the wind tunnel becoming so well known.
TOUR: Nowadays, there is hardly a new competition bike on the market that has not been aerodynamically optimised in the wind tunnel. How do you see this development?
Pfeiffer: Aerodynamics is a huge hype. Bikes are already extremely sophisticated. The last few watts that you want to squeeze out are becoming incredibly expensive. At some point, the realisation will prevail that one or two watts are no longer decisive. Of course it's important for the manufacturers to have the fastest bike in the TOUR test. But apart from the bikes, I see even more potential in helmets and jerseys.
TOUR: Hand on heart: Are there any road bike manufacturers who have tried to cheat the measurements to achieve a better result? After all, aerodynamics are a strong selling point.
Pfeiffer: No, I wouldn't go along with that either. Every manufacturer makes their bikes as fast as they can. I know that there have been discussions between manufacturers because of different results. But this is usually due to measurements with different tyre widths. The thing is quite simple: I get wheels from the manufacturer - and I measure them. I'm a measurement technician and not a developer. The customers tell me what to measure. How the results are interpreted is up to the customer. Of course, there are times when apples are compared with pears. For example, when a bike with 25-millimetre tyres is compared with a model with wider tyres. But that's for everyone to judge for themselves.
TOUR: What proportion of your wind tunnel is dedicated to cycling-related measurements? You also have other test benches for wind turbine rotors or aeroplane propellers.
Pfeiffer: In total, there have been well over 1000 bikes so far. Over the past five years, half of the wind tunnel's capacity has been utilised by measuring racing bikes and components. The second basis is small wind turbines. This year there was also a lot of aviation, such as air taxis. That's why I had to cancel three top triathletes this year who were planning to compete in Kona. (Ironman World Championship in Hawaii, editor's note) have started.
TOUR: What is the particular challenge of measuring racing bikes in the wind tunnel?
Pfeiffer: On the one hand, the rider, whether it is a dummy as in TOUR or a real rider, has a major influence on the resistance. Pedalling creates forces that are greater than the air resistance. This must of course be taken into account and factored into the measurements. On the other hand, the rider's sitting position influences the measured values. For reproducible results, the rider must always sit exactly the same way on the bike. These measurements are the most difficult ones I take.
TOUR: Are measurements of aerospace products easier in comparison?
Pfeiffer: You can't say that. The actual measurement is certainly more complex with bicycles, as there are so-called detached flows. This means that air turbulence and pressure fluctuations occur, which influence the cw value. With aeroplanes, on the other hand, the flow is in contact with the wing. In this case, however, the low flow velocity compared to reality and the necessary modelling scale make the measurement procedure more difficult.
TOUR: You have been running the wind tunnel for almost 20 years. Were there any breakdowns or did anything break?
Pfeiffer: (laughs) I can't remember any major incidents. With the bikes, things mostly went smoothly. Perhaps that's also down to my temperament. Among the German manufacturers I have the nickname "Bastel-Ernst". Because I would say that I know how to help myself when a minor problem arises. Even my family now call me that.
TOUR: Let's take a look into the future: the UCI changed the regulations last year and now allows more aerodynamic frame shapes. With the Simplon Pride II, a racing bike has already surpassed the 200 watt mark. Will such values become the rule in future?
Pfeiffer: I can imagine that, yes. Once the new bikes have been developed according to the new regulations in the coming years, these 200 watts will drop more often. There will be another jump. I reckon that we'll soon see 195 watts. An already really fast bike can become another five or seven watts faster.
Julian Schultz
Editor
