Unless you knew it was there, you probably wouldn’t spot the abandoned Catesby Tunnel.
Its entrance is shrouded by trees, buried in the Northamptonshire countryside, while its 2.7km-long body cuts beneath the grassy hills, in the middle of England. Built in 1897, the tunnel was later cast aside by the railway network, and hasn’t seen a train in almost 60 years. Today, however, it enjoys a new life as a state-of-the-art aero testing facility, and this month, it welcomed a series of visits from WorldTour team Red Bull-Bora-Hansgrohe.
The idea to go to the site came from Dan Bigham, the squad’s head of engineering. An Olympic silver medallist on the track, the Brit has dedicated his career to the pursuit of speed. He saw a unique opportunity in Catesby.
“The tunnel is a great one for having the realism of riding a bike, but with very well controlled variables, like speed, yaw angle and road surface,” Bigham told Cycling Weekly.
The facility is arrow-straight, unaffected by wind or extreme changes in climate. Previously used for testing cars, Catesby's conditions make it similar to a real-life wind tunnel, where riders can experiment on moving bikes as in a race, rather than static ones.
“You can be really, really precise and confident in what you’re measuring,” Bigham said.
Earlier this month, Florian Lipowitz became the first WorldTour rider to test inside the tunnel. He then went on to place fifth in the time trial at the Critérium du Dauphiné, and third overall, behind Tadej Pogačar (UAE Team Emirates-XRG) and Jonas Vingegaard (Visma-Lease a Bike).
“I don’t think I can proclaim that one single test has turned [Lipowitz] into the animal that he is today,” said Bigham, “but I guess it’s part of the reason.”
Red Bull-Bora-Hansgrohe’s visits to the tunnel have come as part of a research and development project, which involves testing new clothing, such as skinsuits and overshoes, as well as improving riders’ positions on the bike. Last week, Jai Hindley and Nico Denz also travelled to Northamptonshire, becoming the second and third WorldTour riders inside the facility.
“It wasn’t, ‘Let’s go there and test for the fun of it’,” said Bigham. “It’s part of a bigger project to really understand all our test systems and to get correlations, so that we’re confident when we bring gains from one place to the real world, we’re going to actually see those gains manifest themselves.”
Already, he added, “we’ve made some big improvements – it gave us some really interesting data.”
“When I was trying to push things forward on the track, towards the Olympics and Worlds, I would find half a per cent gain and be like, ‘Amazing!’. Here, we’re leaving with like whole percentage point changes, which is really, really satisfying.”
Bigham and the team now hope that those gains will come to the fore as early as next month’s Tour de France, which starts in Lille on 5 July. The team will go to the race with Primož Roglič as leader, flanked by the promising Lipowitz.
“It’d be nice to really fight on the podium, not just leave Tadej and Jonas to fight on the road,” Bigham said. Any result will no doubt have been crafted on years of training and racing experience – with a small supporting role from an disused UK rail tunnel.
