Equinox

I noticed throughout the tour this year that a number of riders were using helmet covers, The yellow jersey wore one today. I thought they were mostly for cooler weather. I was curious why?

chasm54

aerodynamics

colombo357

Insect barrier

DiabloScott

They aren't covers, they're a new helmet design that doesn't use vents in the top.
Performance advantage is probably BS, style doesn't appeal to me, helmet cam mounts won't work.

chasm54

Not to reopen the argument from the other thread, but that isn't what the wind tunnel data says...

Equinox

They look strange because it appears that they just filled in the vents. The ribbing is still present, and I assume that is to break up the air mass similar to the dimples on a golf ball. I wonder if the aerodynamic gain is enough to offset the reduction in ventilation.

Bacciagalupe

I'm sure the guys in the solid helmets are cooking, but it's not bad enough to bother them.

I'm rather skeptical that they do any good. Fortunately, I don't need to wear 'em.

Equinox

I just find it interesting that they seem to invest so much research and development into coming up with the best ventilation systems, and then, they basically just cover it up. When you balance the two factors; aerodynamics v. ventilation, is this a solution to a problem that doesn't exist.
It is like runners who wear those amazing skinsuits with high tech fabrics and custom fit, then the athlete wears a big honking necklace.
Also with cyclists, they do all of this exquisite wind tunnel testing to design clothing and determine the most aerodynamic position. But did you ever notice how the back collar of the jersey (at the back of the neck) always seems to catch the wind and flutters in the breeze. You'd think they'd be able to figure out a way to limit that aerodynamic drag.

DXchulo

Yeah, that filled-in helmet probably isn't the best solution. The new helmet that Giro came out with (https://velonews.competitor.com/2012/...-helmet_224988) makes more sense if you want an aero road helmet.

FWIW, the high in Paris was only 73 F yesterday, but it wasn't the only day Sky was wearing those helmets. Wiggins seemed to wear his quite often, which really stood out in yellow. I wonder how high it got on the warmest day he wore it.

DXchulo

You'll see guys wear skinsuits on sprint stages sometimes. Cav was wearing one yesterday.

Bacciagalupe

Yeah, well.

It's mostly marketing. The reality is that the equipment is about as good as it's going to get, so the next step is "specialization." Instead of one helmet that is sufficient for all your rides, you can now buy two! One for climbing days, and one for sprint days. Instead of one bike that does everything well, you can have two or three! An "aero" bike for sprint days, a super-light bike for climbing, a bike with disc brakes for wet days....

fly:yes/land:no

well, the aero road helmet is kind of new in terms of the road market. take giro and lazer as two examples. they made the genesis and atmos several years ago, and have not really updated they much since then. when they made those helmets, the most important characteristics that roadies wanted was weight and ventilation. so they made a lightweight, well-ventilated, "cool-looking" helmet. incidentally, lazer also made a "rain cover" - a clear plastic shield that covers the helmet for rain or cold weather.

if you look at pics from track racing going back to the early 2000's, you see lots of track riders using traditional helmets with rain shells. at the same time, roadies have taken the approach that aero is king in terms of equipment. everything from bikes, to wheels, to components, to uniforms have been refined to be more areo over the past 5 years. so, roadies, after inferring that helmets make a significant factor in the aero equation, looked to improve the aerodynamics of helmets. it isn't quite acceptable to wear an aero helmet to a road race, so the roadies adopted a shield/shell approach. the first time i can remember seeing it was the 2008 tour de georgia team time trial when slipstream and giro created fabric shield covers for their helmets (they weren't allowed to use them, but the product was never offered for sale). in 2010, katusha used the lazer rain shields at the tour of flanders. in 2011, cav used a rain shield to win worlds. the uci clarified its position so that rain shields cannot be used, it must be manufactured as one unit. so, companies had two options - manufacture the helmets with the rain shields 'mounted' to the helmet, or make an entirely new aero road helmet. lazer went with the previous approach. after all, it required almost no retooling - they already had the helmets and the covers produced, now they just have to bond them together and ship them to the team. that is why lazer and many other helmet makers have shields covering the vents that they invested so much into designing. giro, on the other hand, went all out and developed an all new aero road helmet.

why i would not deny the fact that the helmet companies are trying to make money by selling products, i would certainly not dismiss the idea that the shields can help if their is data or evidence to support it. i have been training and racing with a rain shield on my lazer since late 2010. initially, i caught a lot of flak. after cav won with the specialized shield, though, a lot of the local guys have gone out and gotten a rain shield. i have even seen some guys riding aero helmets at crits.

Equinox

Very interesting

Bacciagalupe

I spent a bit of time crunching the numbers of Tour de France ITT's since 1970. I excluded ITT's with serious climbs, but included prologues and split stages.

For 1970 to 1976, the average ITT winner's speed was 45.62kph. 1980 to 1989, 46.47kph. 1990 to 2000, 50.08kph. 2000 to 2010, 50.74kph.

As best I can determine, in 1991 Indurain used a metal round-tube frame, solid spoke and disc wheels, aero bars and an aero helmet. Indurain averaged 51.24kph on stage 21 (57km course) using a bike that probably weighed 25 pounds.

No one would be caught dead using a bike like that today. Yet in 2010, Cancellara averaged 51.15kph on Stage 19's 52km course. Wiggins averaged 50.16 on stage 20 (53.5km)

There was a big improvement in ITT times after 1989, i.e. after aerobars went into wider use. After that, the improvements in ITT's appear to have been extremely small -- despite vastly improved training techniques, users switching to power meters and power-based training, the switch to carbon fiber, carefully sculpted frames, internal cable routing, reductions in bike weight, greater attention to aerodynamics, significant reductions in overall Tour length and the rise of the "Tour specialists."

Obviously, teasing out one specific factor like "bike aerodynamics" from the various figures is very difficult, and I don't know if we would see the same thing for flat sprint stages. So I hesitate to draw too definite of a conclusion. But at the moment, yeah, I'm kinda skeptical.

fly:yes/land:no

the fastest time at alpe d'huez was set in 1997 by pantani. in the all time top 10, one is from 1994, one is from 1995, three are from 1997, one is from 2001, two are from 2004, and two are from 2006. the best time from 2008 (sastre) is 17th. the best time from 2011 (s. sanchez) is 24th. despite the vastly improved training techniques, users switching to power meters and power based training, the switch to carbon fiber, carefully sculpted frames, internal cable routing, reductions in bike weight, greater attention to aerodynamics, significant reductions in overall tour length, and the rise of tour specialists, the more recent riders are slower. why could that be, and given the results from this data point, are you similarly skeptical that lighter weight results in higher climbing speed?

using time trial times from a tour is kind of a bizarre way to discredit the benefits of aerodynamic improvements given there is so much noise involved in those events - i.e. wind direction, speed, elevation change, etc. and especially when considering the recent history of cycling and doping. bike racing is not the product of 1 input, and simply because one input may be outweighed by a culmination of other inputs does not mean that it has no effect or that it should be ignored.

when multiple independent testing labs validate claims of aerodynamics and quantify the results to something that i can understand as a racer, then, yeah, i'm kinda convinced.

Bacciagalupe

Actually, if you do a chart dating back to 1985, you will see patterns.

There is a precipitous drop in Alpe climb times between 1985 and 1995. Times stabilized until around 2006, and have ticked up a bit after that. Unsurprisingly, when you selectively pick out isolated data points, you miss the trends.

From there, you'd need to get a list of the bike weights used on those climbs, and look for potential correlations. Even so, we know that bike weights stabilized at 15 pounds around 2000. Thus, we might hypothesis that "something started happening in 2006 to increase times."

More importantly, it isn't hard to determine that weight changes might not be responsible for most of the changes. For example, if Alpe D'Huez is roughly an 8% grade for 8 miles. At 400 watts on a 15 pound bike, hypothetically you'll climb it in 39' 45". Every pound adds about 15 seconds to your time; so a 21 pound bike adds 90 seconds. That's definitely significant. However, we see times dropping by over 10 minutes between 1985 and 1995. If there's a 10 minute improvement with only a 6-pound weight savings, presumably something else is going on.

The Alpe timing, though, has numerous shortcomings. Riders also aren't consistently soloing up the hill; sometimes they have teammates, others they do not. The timing was not rigorous until recently, and there are only 13 years out of the last 25 when it was timed. In theory you could say "riders got significantly slower between 2006 and 2011," but we only have data for 3 years out of that 6-year period. It's just not a good enough data set to draw a strong conclusion.

ITT's are a better means for examining trends, especially with bike aerodynamics.
• There's at least one ITT every year, going back decades.
• Every Grand Tour has ITT's. (I.e. the data will get better as more ITT's are added.)
• There's a large data pool.
• The riders are not drafting.
• The timing is rigorous.
• Manufacturers routinely express aero gains based on TT's, e.g. "save 60 seconds on a 40k ITT with this widget."


We're talking about around 120 time trials since 1970, and about 50 since 1990. The changes in temperature, elevation and length get averaged out.

Needless to say, we expect vast improvements in ITT performances since 1990. Again, we see a visible pop right after aero bars went into common use -- but almost nothing after that. If the improvements are not large enough to rise above the noise, then on what basis should we assert they are, in fact, significant?

Similarly, should we really be that surprised that all the geegaws are, in fact, offering minute improvements over the round-tube TT-specific bike, since the overwhelming majority of drag is just a result of rider position...?

(By the way, I've noticed that people are happy to take sketchier stats to make sweeping claims, such as "average TdF speeds are lower now, so obviously people aren't doping anymore.")


When those lab results don't produce tangible results, I'm not.

My favorite example of this is Cavendish, who has used a variety of bicycles in his career so far: Scott Addict, Specialized Tarmac, Specialized Venge, and now a Pinarello Dogma 2. Cav crushes everyone, regardless of what bike he's using, including blasting right past everyone on Stage 18. Most of the time, at least one rival sprinter is on an aero road bike. (Many times, the winner is not -- cf Sagan and Greipel this year.)

So on what basis would we say that aerodynamic thingees have measurably contributed to Cav's successes? Or, if his natural and trained abilities overwhelm those aero advantages, then why should we regard them as significant?