The road was closed for three-and-a-half hours to allow officers to carry out investigations at the scene. Officers would like to hear from anyone who witnessed the collision or saw the motorcyclist prior to it.
Anyone with any information should contact Totton Roads Policing Unit, quoting Operation Froggen, on 101, or the Crimestoppers charity anonymously on 101.
More top news
A report by Dogs' Trust revealed dogs in the care of local authorities couldn't be returned to their owners.
The company was fined after the court heard an engineer "felt pressure" to get the ride back into service after an earlier fault.
A challenge to the decision not to take further action against Sir Cliff Richard over alleged sex offences has been dismissed.