Cycling, Gear, Podcast

Dan Bigham – aerodynamic testing, equipment, and making your bike fast | EP#229

 April 13, 2020

By  Mikael Eriksson

LISTEN TO THE EPISODE HERE:

​Dan Bigham is a multiple British Champion (Time Trial and track), a member of the Huub Wattbike track team, and an aerodynamics consultant who recently helped the Danish track team beat the team pursuit world record. In this episode Dan goes into many of the most important aspects of optimising aerodynamics on the bike.

In this Episode you'll learn about:

  • Aerodynamics testing protocols: on the road, at the velodrome and in the wind tunnel
  • On-bike aerodynamic sensors and their use cases
  • Bike fit and aerodynamics
  • Equipment, upgrades and the £/watts ratio

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Shownotes

About Dan Bigham

03:30 - 

  • I used to be a triathlete but wasn’t that good at either swimming or running, cycling was my by far strongest discipline, so around five years ago I transitioned into road cycling and time trialing and since three years back I have been focusing on track cycling.

    I sat up my own track cycling team, which has been competing and winning at world cup level.
  • My academic background is as an engineer and aerodynamist, and I have been working as that in different capacities, for instance within formula 1 and cycling.

New 1h track world record

04:48 -

  • I was part of the team around the Danish attempt of breaking the 1h world record on the track, I contributed with knowledge around basically everything that wasn’t on the ”physiology side”.

    Before the world record attempt I was quite confident that the record would be beaten, but by as much as it turned out was a bit of surprise, this makes my job even harder as my team is in the process of trying to make an attempt of breaking the world record.

Huub Wattbike track cycling team

06:08 -

  • Shortly after the team was started we had great success at the national championships, winning multiple titles there.

    With time, we started to get the chance to race at the world cup and even the world championships.
  • We are not a part of the British cycling federation and they don’t seem that interested in working together with us despite that we or our riders for most of the time beat the British national team or their team members.

    Also, the British track cycling team doesn’t seem that interested in our riders nor exchanging knowledge, which is a bit of a shame for British cycling as I am sure that we together could achieve pretty outrages results.

Getting faster on the bike - testing

09:10 -

  • At University I was lucky as I had a lecturer that was really into cycling and he introduced me to all the important metrics that influence performance.
  • With the track team we are using wind tunnel testing, velodrome testing and field testing, which all have their place.

    For example, if one finds 50w savings in the wind tunnel but cannot see the same results in the velodrome or the field, then these findings does not have much value.

    We have found that the correlation between the wind tunnel results and velodrome testings are not that great when it comes to helmets and head position but is fairly good when it comes to race suits.
  • We also use special sensors that are attached to the bike, which measures things as body movements, air speed, etc., which also have their place in our testing.

    Another thing is that we are using special head units that can receive data at a much higher velocity than once every 1 second, which is typical for most head units.

    This has made it possible to analyze the data in much more details, which has been very helpful to us in several ways.
  • One very important aspect is to do all the tests in your intended race speed since air flow are quite sensitive to different speeds and could possibly greatly influence aspects like head and arm position.
  • In order to get the right impression of wether the changes you are testing actually does influence your CDA-value or not, a great strategy for this is to have a test circuit, which you on one day are riding at least 6 times (the more the better) and from these rides you calculate your CDA and standard error from this CDA.

    If you later go on and try another position or gear and find that the new CDA after doing the adjustment is outside of your standard error CDA from the multiple test rides, then you can be rather confident that this is an actual change on your CDA.

On bike sensors

23:40 -

  • I have found them to be very helpful tools in my pursuit for more speed, however, wether age group athletes will get the same benefit from them is hard to say.

    For those really interested in aerodynamics or those amateurs at the very pointy end they will definitely become gradually more popular, but they won’t for sure breakthrough to the same extent as power meters in the years to come.

Bike fit aspects

26:35 -

  • In most triathlons and time trials, the important metric is watts to CDA, the weight isn’t that important on most courses.

    When trying to maximize the watts per CDA, one needs to point out that the watts produced have the ability to respond to physiological stimulus, which your CDA does not.

    This means that one could actually when trying out a new position on the bike give up a little power in advantage to a better CDA as over time one can probably make up for this power loss over time in training.
  • Before doing aerodynamic testing I always recommend the rider to do a thorough bike fit and also instruct the rider to feel where his or her limitations in regards to saddle height, cleat position etc. are so that one only can test different possible scenarios.
  • I think that it could be wise to consult several bike fitters and aerodynamisists as they tend to advocate for different ”schools”, and you have to find out what works best for you, and in order to do that it can be really beneficial to bring in someone with a completely new perspective.

Equipment

32:50 -

  • Once you have set a price limit for what you’re prepared to spend for every watt saved, then it is actually rather easy to know where to start the process.

    The most cost effective thing out there is probably aero socks and shoes cover, they can yield a saving up to 10 watts and cost maybe 20-30 pounds.

    Also a clean drive train can save you many watts in power transfer and is basically free.

    Tires is also a pretty cheap upgrade that can save you maybe 10-20 watts, sometimes even more in terms of rolling resistance, many people tend to favor puncture resistance before rolling resistance but if choosing a fast tire then you could actually make up the time for an eventual puncture…
  • On the aerodynamics side the most important aspect is probably position, which is even more complex when it comes to triathlon since you have to take into consideration that you must be able to run well after the bike leg, which makes the comfort aspect even more important.

    To get good inspiration one can look at the British national time trialists and how they are sitting on the bike, this is because the UK doesn’t have the same strict regulations compared to the UCI in regards to how the rider is allowed to sit on the bike.

    One cannot always copy straight from the best but most of the time it poses a good position to start from, picking the same helmet or extensions as one of the best does not necessary mean they are the fastest ones for you.
  • One very interesting aspect of wheels is the stability factor, basically how stable the wheels are, which becomes increasingly more important the more technical the course is, this is also a factor that is often neglected by many.

    Generally I would say that a mid price range wheel set (around 2000 pounds) is ”good enough”, the advantage of getting a really high end wheel set (in the range around 5000 pounds) does for most of the time not generate a significant increased performance.

    If the course is hilly, then also the weight of the wheels come into play, but for most of the triathlon courses, the weight of the wheels is not that important.
  • When it comes hydration system, a very safe position to put your bottle is behind the saddles, it is almost always aerodynamic neutral or in some cases even faster.

    One should generally be careful about putting a bottle between the arms in the front as it can come with an aerodynamic penalty and also decreases the possibility to go really narrow with your arms, which for some people can be massively beneficial.
  • In regards to which products one should not prioritize to spend your money on I would say that ceramic bearings is probably not going to make that much of a difference, the most important thing is to keep the drive train really clean.
  • In general a dry lubricant is better than a wet lubricant and a wax or paraffin based coating is an even faster option.
  • In summary, I think that one needs to be smart to be able to win, make a list about potential improvements that can be made, which can be position, wheels, tires etc. and then start to test the different alternatives.

    Being consequent and methodological in the testing procedure is a key and never ever think that there aren’t any more rooms for improvement!

Rapid fire questions

49:30 -

  • What is your favorite book, blog or resource related to triathlon or endurance sports? Alex Hutchinsons Endure, it made me more interested in the physiological parts of the performance.
  • What is your favorite piece of equipment? My SRM power meter, it just gives me a bit of everything.
  • What is a personal habit that has helped you achieve success Obsessive over details.

​LINKS AND RESOURCES:


Mikael Eriksson

I am a full-time triathlon coach, founder of Scientific Triathlon, and host of the top-rated podcast That Triathlon Show. I am from Finland but live in Lisbon, Portugal. Please contact me if you have feedback on the podcast or want to make suggestions for improvement or send in a question for a Q&A episode. If you are a long-time listener and appreciate the value the podcast brings, please consider taking a couple of minutes for leaving a rating and review on iTunes/Apple Podcasts, or wherever else you can think of leaving a rating and review.

Mikael Eriksson

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