What factors affect success or failure in an Hour Record attempt? Just about everything, from the altitude, temperature and humidity, right down to the rider's shoes. With Dame Sarah Storey's attempt on the women's record looming, we take a look at the elements of success or failure in breaking cycling's blue riband record.
On February 28 Sarah Storey will take to the track at London’s Lee Valley VeloPark to attempt the hour record.
Storey is the first female athlete to attempt the record since the rules were changed and she will need to beat the 46.065km (184.26 laps) marker set by Leontien Zijlaard-van Moorsel in 2003.
Thomas Dekker at the Aquascalientes track in Mexico
Storey has chosen to undertake her attempt on the velodrome at London's Lea Valley VeloPark. It's among the world’s fastest and the 4000m record set there in 2012 still stands.
If Storey breaks the record this would be the first time a successful attempt has been made outside of Switzerland since the rules were changed allowing modern track bikes.
Voigt and Dennis broke the record at the Velodrome Suisse, Grenchen, and Brändle used the UCI’s World Cycling Centre Track, Aigle. Bobridge tried at the DISC Velodrome, Australia, but failed.
According to sports scientist and performance consultant Dr B. Xavier Disley, this will not be a coincidence.
He says: "Velodromes have varying characteristics, ranging from lap length, wood type, geometry, altitude and ability to control ambient conditions. The Swiss tracks in Grenchen and Aigle are both at altitude (450m & 380m), resulting in a gain of between 350-500m over the course of an hour compared with the equivalent track at sea level due to reduced air density at altitude.”
According to Disley, the DISC Velodrome’s high temperature in January should have also made it quick, but this would also increase dehydration.
And while Dekker’s attempt, which took place at the Aquascalientes track in Mexico (1880m), didn’t break Dennis’ record, he fell just 270m short and sits second in the record book.
Altitude has been important in the history of the Hour Record too. Perhaps the most iconic record, Eddy Merckx's 49.431km of 1972,was set at 2,200m in Mexico City. Merckx broke Ole Ritter's 1968 mark of 48.653km, also set in Mexico City, but the previous mark, Ferdi Bracke's 48.093km, was set at in Rome in 1967.
Modelling of the power output needed to set their respective records reveals that Bracke generated significantly more power than Merckx.
Lee Valley Velodrome can't duplicate the reduced air resistance at 2,200m, but it does allow some adjustment to the atmospheric conditions for Storey's ride.
Disley says: “Lee Valley Velopark in London is unique with an airlock style construction around the outside of the building, allowing for atmospheric conditions to be regulated to a far greater extent than other velodromes.
"Being able to manage temperature and humidity will provide a benefit equivalent to a few hundred metres altitude, but without the small decrease in power output due to reduced oxygen partial pressure levels."
In an interview with the Guardian, Storey said: “I expect the last 20 minutes to be brutal so I had better enjoy the first 40. I’m trying hard to prepare, but there is this sense that I’m venturing into the unknown.”
She added: “There’s an element of doubt in our minds when thinking about a whole hour. Men are more used to it because their time-trials and stage races are longer.”
Wednesday’s attempt by Dekker suggests Storey is right to be apprehensive. Dekker's power dropped by approximately 20 watts in the final third of the ride.
Wattbike’s lead sports scientist, Eddie Fletcher says: “To cope with those last 20 minutes, she’ll need to get the pacing spot on from the off.
"We saw Bobridge go too hard and then the inconsistency crept in.
"Dennis on the other hand was consistently running 17-second laps and while this started to drop at around 45-50 minutes he never dropped below 17.8 seconds and could, unlike Bobridge, climb off the bike easily.”
Storey has already announced the bike, which will be built around a Ridley Arena Carbon Track frame with an F-Split fork that has twin vertical slits to reduce turbulent air between the fork and wheel.
The Arena also uses Ridley’s F-Surface, in which slim strips of material are applied to the leading edge of the frame in key places to trip the passing air into turbulence and shift the separation point further along the tube profile. Ridley reckon on the Noah Fast frame road.cc tested a couple of years ago, the F-Surface is good for a 4.02% decrease in drag at 50kph.
The frame will be equipped with a Verve Infocrank crankset with integrated power meter, Shimano Dura-Ace chainrings, chain, sprocket and SPD-SL pedals. The gear ratio hasn’t yet been announced, but Voigt and Dennis both used comparatively modest gears - 56x13 and 56x14 respectively - to enable a high cadence; Dekker went for 58x14 gear ratio but was unable to keep the required cadence for the full hour.
In a recent interview on product development with Team Sky’s head of technical operations Carsten Jeppesen, and helmet-maker Kask, Jeppeson told road.cc that cycling has seen a huge leap in understanding and performance in recent years, but it’s getting harder to make gains.
“If we want to have the same gains again, it's going to be really tough to make that big a difference. We know more or less what a total drag of a rider or the unit is, the whole thing. And we [now have to] try to look as much as we can at the full package, so we make a helmet that fits the clothing and the bike and so on.”
So far the riders who have attempted the Hour Record have left nothing to chance. The gains from skin suits and aero helmets are well known and Storey has announced she will be using a Pearl Izumi skinsuit, with the same design as Rohan Dennis used in his world record ride, and Team GB’s Lazer helmet.
But these are not the only areas where companies are turning to the wind-tunnel when developing. Even rider's shoes are being examined for their aerodynamic impact.
According to a report by aerodynamic analysis firm dqbd, Rohan Dennis’s hour-record shoes have the lowest coeficcients of drag (cx) of any tested by the firm.
The report’s abstract says there are three factors to consider: skin friction drag (the air resistance on the shoe); the form drag (the pressure drag from the shape of the object); and the wake (the flow of air behind the moving body).
“In the case of Dennis’s fi’zi:k R3M-B shoe, the very clean upper surface not using too many exposed objects such as Velcro flaps and 2 boa wheels, etc. are beneficial to the overall skin friction [drag] of the shoe.
“Form drag or pressure drag arises because of the shape of the object. Here you can notice that the R3M-B shoe has a very streamlined shape that decreases the pure drag area with narrow wake and therefore lowers the drag coefficient.”