The team time trial which opened this year’s Giro d’Italia may only have been 22km and 25 minutes long, but it packed in more drama and tactical intrigue than many 200km-plus stages. Let’s examine why a little rain makes such a big difference.

The course

Belfast offered a well-balanced course which presented two distinctly different challenges – opening and closing sections which were twisty and technical, and two long straights dominating the middle portion of the stage.

At under 22km, the final time gaps were larger than expected. Only five teams finished within 50 seconds of winners Orica-GreenEDGE. Or, put another way, for every minute the Orica riders were on the course, 16 of the 22 teams were at least two seconds slower (four seconds for every minute in the case of 21st-placed Europcar). That’s a huge difference.

Some race favourites such as Joaqium Rodriquez, whose Katusha team has a known aversion to time-trialling, would have expected to lose a chunk of time. But the Spaniard would have been hoping to limit his losses against other GC rivals to perhaps 45 seconds. Instead he conceded nearly double that (1:28, to be precise) to Rigoberto Uran, who will expect to take even more out of him in the stage 12 individual time trial. Not good.

OPQS’s performance was hugely impressive given the disadvantage of riding in the wet (Image: Giro d’Italia)

The single biggest factor in the increased time gaps was, of course, the variable weather. Orica, the second team out, enjoyed dry conditions, but by the time the other front-runners such as BMC and Omega Pharma-Quick Step headed down the start ramp rain had been falling over much of the course for over an hour.

Wet roads mean treacherous handling, greater caution and slower cornering speeds at the best of times. But in a team time trial the effect is much greater than in a standard road stage.

Disc versus standard wheels

The differences are exacerbated by the use of solid disc rear wheels, which further increase the disadvantage for those running in wet conditions.

Rear disc wheels are de rigueur in track cycling but are only seen in time trials on the road. They offer significant aerodynamic benefits over regular wheels, where turbulent air passing between the spokes causes significant drag, allowing higher speeds to be achieved with less effort when travelling in a straight line.

However, they come with the downside of being trickier to handle in the corners – think how much harder it is to change direction in a yacht versus a rowing boat – which is why they are not used on standard road stages and also why you never see bikes being ridden with two disc wheels, as the incremental aero benefit comes at too high a cost in terms of handling.

Disc wheels are a huge benefit in dry conditions, but make bikes a real handful in the wet (Image: Giro d’Italia)

The resultant effect in individual time trials is significant. Corners which are comfortable in the dry become tip-toe affairs the moment the road surface becomes even slightly damp.

In team time trials, the uncertainty of how grippy or slippery any given corner is results in lower cornering speeds, which reduces the aero benefit afforded between one rider and the next. It often also results in a visible increase in the distance between teammates as they pass through a turn. It may only be a matter of 10cm, but in aerodynamic terms the increase in drag between following 20cm behind the man in front of you and 30cm can be measured in double-digit percentages.

And that’s the issue that faces teams riding in the wet: they face the double whammy of less grip and reduced aerodynamic gain in the corners. Although Orica-GreenEDGE were the fastest team according to the clock, for me the most impressive team performances of the day came from OPQS and BMC, who finished five and seven seconds behind in far less favourable conditions.

To watch both these teams’ speed, discipline and focus in such terrible conditions – and with the knowledge of Dan Martin’s crash (he lost control hitting a manhole cover), which scuppered not only his but his entire team’s hope of GC success – spoke volumes of the bravery and trust between these men. It’s that which made yesterday’s TTT such a fascinating spectacle.