Why are rain jackets so big?

I was asking this on Twitter during Stage 11 of the Giro. As the rain poured down, the desperate chase by the GC contenders and their team mates wasn’t helped by seemingly inflatable rain jackets. The same goes for the breakaway riders, when Dario Cataldo jumped away with 3km to go, he was wasting many watts because of his bulky jacket. The sleeves are cut big enough to house his thighs, no?

My kingdom for an aero rain jacket

Now keeping dry matters. A jacket won’t keep you bone dry but it slows the evaporation and holds in body warmth, so you can’t just ditch the jacket when you need to race. Yet in a sport where aerodynamics is applied even to cable routing, where a Grand Tour is on the line, why are these jackets still so big? It’s not like rain is a freak event, riders have to brave the elements all year round.

So you’d think jackets would be cut to suit the slim build of a rider, or made a material that could stretch?

Respondents on Twitter pointed out that Cervélo Test Team has appropriately enough been testing some new jackets. I too had seen this, take a look for yourself at the video below.

As Heinrich Haussler says “You’re gonna have the biggest advantage because the guys have got their rain jackets on, flapping around. You’ll save so much energy.” But what’s taken so long? Note that these jackets weren’t being used by the likes of Carlos Sastre and Xavier Tondo, they still had the traditional inflatable version.

I can think of two reasons why better jackets haven’t arrived. First, they are an afterthought, no one will get too excited by rain jacket just as umbrellas have barely changed in 100 years. Second, a close fitting jacket is harder to put on and off. It’s not easy putting these on mid-race, they can catch the wind like a spinnaker just when you have the hands off the bars, so a looser fit does have advantages.