The incident occurred at around 7.45am on Thursday on Route de St Aubin, which was subsequently closed from the junction of Tyneville Lane and West Park roundabout.
The rider was taken to hospital, but the 53-year-old man driving the other vehicle, a white Nissan, was not injured.
Around an hour later, a pregnant woman was taken to hospital after the grey Volkswagen Golf she was driving flipped over on Rue du Pont Marquet – within the accident blackspot area.
It is believed the vehicle clipped a boulder. The route was closed from between the Lavender Farm to the junction of Rue du Coin.
The incident was the second to have occurred in the area in under 24 hours. At 4.20pm on Wednesday States police officers were called to the same road after a 16-year-old boy on a blue 50cc Aprilia moped was involved in a collision with a white Jeep driven by a 50-year-old man. Neither had to be taken to hospital.