Long before the bikes arrived, the cars came. Ballaugh Bridge formed part of the Highland Course, a 52.15-mile circuit used for early motor racing on the island - amended to 40.38 miles in 1906 - and of the 37.50-mile Four Inch Course used for the 1904 Gordon Bennett Trial and for the RAC Tourist Trophy car races that ran between 1905 and 1922. In the very earliest configuration, the bridge was the western edge of something called the Sandygate Loop, used for the 1904 Gordon Bennett British Eliminating Trial and the 1905 Tourist Trophy. By 1906 the loop had been abandoned in favour of a route running the A3 Castletown-Ramsey road from Ballacraine corner all the way to Ramsey. The story of British motorsport in its first two decades passed across this bridge before motorcycles entered the picture at all.

In 1911, the Auto-Cycling Union adopted the Four Inch Course for the Isle of Man TT motor-cycle races. Ballaugh Bridge was inside the route. That same course - or rather, what it has evolved into - is now the 37.73-mile Isle of Man TT Mountain Course, used continuously for the TT since 1911 and for the Manx Grand Prix since 1923. The Mountain Course is unusual in nearly every respect. It runs across closed public roads, climbs over 1,300 feet of mountain, passes through several villages, and has approximately 264 corners over its lap. Riders memorise it in sections, learning the cambers of individual stretches of tarmac the way a violinist learns a concerto. Ballaugh Bridge is one of the corners they cannot afford to misjudge. Land flat and the bike's frame can be damaged; land badly tilted and the rider can be thrown.

The bridge has not survived unchanged. Over the winter of 1953-1954, in preparation for the 1954 TT, the road was widened and the bridge profile altered. The garden wall of the adjacent Ballaugh Railway Hotel - now the Raven Hotel, named for the river - was removed to give racing motorcycles a wider line. Even after that adjustment, Ballaugh Bridge remains the only humpback bridge left on the TT Course. Sulby Bridge was removed in the 1920s. Ballig Bridge went in 1935. The Manx racing authorities have, over the decades, made the course faster and safer by smoothing out the most dangerous geometry - but they kept Ballaugh's hump. The leap has become part of the identity of the race.

Just by the bridge stands a small memorial to Karl Gall, an Austrian motorcycle racer who was part of the pre-war BMW works team. During evening practice for the 1939 Isle of Man TT, Gall crashed near the bridge and died from his injuries. The roadside marker remembers him by name. He was one of the many riders the Mountain Course has claimed over its long history - more than 270 since 1911, including spectators and officials - and the memorials scattered along the route are part of how the island carries that weight. The Manx public roads become a racetrack for two weeks each year. The same hump-backed bridge that launches motorcycles into the air also carries the grocery vans of Ballaugh for the other fifty weeks. The contradiction is fundamental to what the TT is, and Karl Gall's memorial is one of the small honest reminders that the cost of running motor races on real roads has always been real.