Road Helmet Aerodynamics

Discuss light weight issues concerning road bikes & parts.
JamieL
Posts: 381
Joined: Tue Jun 21, 2011 1:05 pm

by JamieL

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.

Image

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.

drchull
Posts: 377
Joined: Sat Jul 30, 2011 6:38 pm

by drchull

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.

bricky21
Posts: 1405
Joined: Tue Sep 14, 2010 3:28 pm

by bricky21

^ 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 :P

Murphs
Posts: 1117
Joined: Thu Feb 05, 2009 12:04 am
Location: Gold Coast, QLD, Australia

by Murphs

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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ave
Posts: 1716
Joined: Sun Dec 28, 2008 10:15 pm
Location: Hungary

by ave

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)

bricky21
Posts: 1405
Joined: Tue Sep 14, 2010 3:28 pm

by bricky21

Murphs wrote: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.


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.

Roeboe
Posts: 243
Joined: Thu May 25, 2006 8:20 am
Location: Zolder, Belgium.

by Roeboe

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

Epic-o
Posts: 621
Joined: Tue Nov 20, 2007 7:18 pm

by Epic-o

JamieL wrote: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.

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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Last edited by Epic-o on Mon Feb 27, 2012 5:21 pm, edited 1 time in total.

beardking
Posts: 261
Joined: Thu Dec 29, 2011 11:22 pm

by beardking

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

HillRPete
Posts: 2292
Joined: Tue Apr 12, 2011 8:08 am
Location: Pedal Square

by HillRPete

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.


Valbrona
Posts: 1485
Joined: Fri Oct 28, 2011 3:25 am
Location: United Kingdom of Great Britain and Northern Ireland

by Valbrona

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.

justkeepedaling
Posts: 1340
Joined: Thu Jan 03, 2008 6:14 am
Location: by Crystal Springs (Sawyer Creek Trail)

by justkeepedaling

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

NGMN
Posts: 1536
Joined: Mon May 30, 2005 7:13 am

by NGMN

justkeepedaling wrote: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.

Valbrona
Posts: 1485
Joined: Fri Oct 28, 2011 3:25 am
Location: United Kingdom of Great Britain and Northern Ireland

by Valbrona

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


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.

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