Marginal Gains – Clothing

For general guidelines on cycling clothing and how to wear it I would refer readers to ‘The Rules’ – mostly they’re about trying to look like a Pro Euro Cyclist, ideally of the Eddy Merckx era. And indeed, I possess appropriate items (steel Eddy Merckx bike with Campagnolo {of course}, Campagnolo woolen jersey and cycling cap etc) to not embarrass myself too much when judged by ‘The Rules’.

However, this is Speedtheory (like Sparta but without the leather) and around here we care about what is fastest with aesthetic considerations relegated to a secondary concern (actually that applies to anything I wear). I shall attempt to avoid Lacedaemonian* brevity in explaining what matters when the focus is on speed.

Rule 1: Make it tight

Flapping clothing catches the wind – as most of us discover with lightweight rain jackets or Gilets. But even wrinkles in clothing disrupt airflow and create extra drag. One of the easiest speed gains you can make is to size down or shop around till you find clothing that is snug all over without being too short. If you’ve watched an elite level time trial you may have noticed that the cyclists all have the zips pulled down when they’re off the bikes – that’s because the skinsuits are so tight that it’s hard to stand up when the zip is fully done up.

Castelli claim significant benefits to using their aero focussed products. Other testing has verified that there is a significant benefit
Castelli claim significant benefits to using their aero focussed products. Other testing has verified that there is a significant benefit

Rule 2: Skin is slow

Much as we all reminisce fondly on the days when triathlons were raced in Speedos and admire Faris Al Sultan for staying true to the ideal – exposed skin is usually slower than well designed fabrics.  Castelli were one of the first brands to make a push for aero features in road and tri clothing and claim to offer substantial benefits in both categories. While truly high tech garments use seams to ‘trip’ the airflow (like dimples) in general you want to look for minimal seams and ensure they’re not running across the direction air will be moving.

Rule 3: You’re unique

I’ve these ‘rules’ in general terms as most things to do with clothing are individual – fit, comfort and speed. A few examples:

  • The prevailing wisdom for years has been that shoe covers are always faster. More recent evidence has shown that booties are like helmets – quite individual. So don’t assume that covering your shoes is necessarily a worthwhile endeavour.
  • Following on from this – just because you see pro cyclists in long socks – doesn’t mean that it is faster (for them or you).
  • Some studies have shown a benefit to compression calf guards – shaping the lower leg and smoothing airflow to improve aerodynamics – but that is undoubtedly also highly individual, just as the effect of bottle placement on the seat tube can depend on the size and proximity of your legs.

Rule 4: White is right

If it is hot. Don’t use this as a general rule – white bike pants are only OK if you are the Road World Champion with the Arc en Ciel emblazoned across your pure white kit and it’s not raining. There is a lot of discussion about treated fabrics to aid cooling but as this runnersworld experiment showed – there is no substitute for the simple physics of reflective colours. So if you’re focussing on a hot race, look for clothing (and helmet) in light colours – even a difference of a couple of degrees will make a difference to thermal stress. Just be aware that you may need to apply sunscreen even to areas that are covered in fabric if the material is very light.

Rule 5: Be Prepared

If you race in New Zealand you are probably going to turn up to an event and be faced with the prospect of rain. For a short race it is possible to suck it up and not suffer any detriment. But if you are doing a long event getting cold could have a significant impact on your performance. So make sure you have back up options that are appropriate – tight fitting thermals, arm warmers, snug gilet (rain vest), skull cap, booties etc. You need to be able to insulate yourself without adding unnecessary bulk (it is still a race afterall). For an event like Ironman it is worth taking a little extra time to put on clothing that will ensure you don’t freeze on the bike – particularly if you’re a smaller athlete. For distance cycling it is a bit easier – you put on your clothes before you start and remove as necessary. At the other end of the spectrum – for very hot races it can be worth looking at arm coolers for sun protection.


Clothing is one of the simplest things you can address in the search for speed. Just choosing a tight fit will achieve most of the benefit of the premium garments with high tech fabrics. And light colours do make a difference in the heat. If you are looking for every advantage Castelli & Pearl Izumi are among the leaders in aero clothing. Whatever event you’re aiming for – be sure to turn up with clothing for a range of conditions – it will give you more confidence (knowing that you’re well prepared) and could make a crucial difference to your end result and enjoyment.

*another reference to Sparta. I’ve waited a long time (~15yrs) to be able to use that word in an article and the reference to Sparta (from the Movie ‘300’) earlier in the paragraph was enough of an excuse.

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