Not sure if people have seen this shot of Alex Dowsett in the KBK this weekend but it seems that the pros are becoming more and more interested in the aerodynamics of their helmets (see world RR 2011 as well). These guys are obviously limited in helmet choice to a set manufacturer and therefore the best they can do is get a helmet cover.



I have just started racing in a new region where the race organisers seem to want to keep the racers away from any gradients and additionally i need a new helmet (number of reasons, main one being my current one doesnt match my new team kit...). Does anyone have a link to an aerodynamic comparison of normal road helmets? i've had a look at google but all i get is TT helmet comparisons.

These are covers for the stock helmets. Lazer, I believe, started it a couple of years ago with a fantastic looking lion of Flanders cover for their helms. It really was started more for inclement weather than aerodynamics. I guess figure it is nicer to clip cover over the helmet than stuff a cap underneath.

Later the aerodynamics were looked at and found to be more aero. There was an article back in the fall after Cav won WC wearing one. At that time though I thought the UCI said that they were illegal because they were a non-structural aero enhancement. Obviously only illegal for Cav. Man they need to fix the UCI.

^ I agree. Those things may give a little bit of aero benefit, but I doubt you'll see them after the temperatures rise.

Racing starts here in 2 weeks, and I'm wondering how many people are gonna show up one of with those covers on there helmets now that it's produced a world champion

The Kask helmets are filled in like that, that is not a helmet cover. Sky have been using them for a number of years in the classics etc

Removable covers are illegal however.

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Why those Kasks mimic the wents if it's not a cover only? A smooth even surface should be better, no? (or with dimples if you believe so)

Which model? The Sky rider behind looks to be using a standard helmet. I can't find that helmet on the Kask website, but I can't find a helmet cover either. Iirc Cav was wearing a cover in the WC road race on his specialized prevail.

I think the main reason is for keeping the head wind and water free, since you lose most energy (heat) trough your head.

0 yaw 30mph. I don't know what they exactly tested, the drag numbers suggest that it wasn't bicycle+rider+helmet so I think it's only rider+helmet

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are all the vents closed or just the ones on the blue stripe?

The issue I have is that rider (head) position in a road race is much more variable than in a TT. That's not to prevent anyone from seeking the holy aero grail, but don't drop your chin when in the wind.

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Something good in a 0 degree yaw is by default useless in a 90 degree or more yaw. Aerodynamics data is not very useful until they start giving you the 0 degree - 180 dgree figures. Cycling is not like making aeroplane parts that move through the air at much higher speeds.

0-180? What the hell are you talking about. Are cyclists now riding in reverse?

You must be unfamiliar with Valbrona, he takes every opportunity where aerodynamics comes up to make a complete ass hat of himself. He is in complete denial of the fact that yaw is not the same as angle of wind because the rider is moving forward and so one must use a vector analysis. When one uses such analysis, effective wind angle as actually experienced by the rider rarely exceeds 20 degrees. However, I have called him out on his ignorance in less forward, and less demeaning ways, and yet he continues to be ignorant and so I again call him out.

Yaw is not the direction someone is cycling in, it is the direction of air flow. And if anyone who has ever ridden a bike knows, you can actually get wind direction in a 360 deg. fashion. Vector analysis does not translate to real life cycling very well - cycling speeds are generally quite low and variable, and wind speeds can be comparitively high. Vector analysis works with objects that move at higher speed than your average cyclist.