Footage shows motorcyclist reaching speeds of up to 170mph before horror crash that killed his best friend

This harrowing dashcam footage shows a motorcyclist reaching speeds of up to 170mph - just minutes before his best friend was killed in a horror crash.
The video has been released by police as a warning to drivers tempted to break the law by speeding during the recent sunny spell.
The terrifying clip shows the bikers Fred Bowden and Andrew Prowse weaving in and out of traffic at the highest speeds ever recorded.
The 25-mile ride in Devon and Cornwall left witnesses fearing for their lives.
Police officer Tim Swarbrick said: 'I would appeal for all motorists to adhere to the speed limit.
'Watching this video was not pleasant viewing and the subsequent incident was a tragedy for everyone, not least the traffic officers who had to attend the collision.
'At that speed, there is just no time to react and what we have seen on the video is truly shocking.
'The footage shows the bike carrying out dangerous overtaking manouvres, contravening white lines and actions which force other motorists to move out of the way.
'Other drivers being overtaken during this journey made comments that one or both of these motorcyclists may die - sadly this proved to be the case.'
With a camera strapped to his motorbike Bowden followed Prowse as the pair broke the speed limit 30 times in just 20 minutes.
He was still filming after 25 miles when his friend clipped a car with his Kawasaki ZX10R and was thrown under an oncoming camper van. Mr Prowse, 46, was decapitated and died instantly.
In a horrific scene inadvertently caught on camera by Bowden, he became 'tangled up' in the vehicle's wheels and his legs and head were torn off.
Off-duty St Ives policeman James Gallienne found a scene of 'blood and unrecognisable body parts' and immediately called 999, the court heard.
The officer told a previous hearing: 'I could see a small video camera mounted on the fuel tank of the black bike - I could see it was still running.'
It later emerged that Bowden had been clocked during the chase at a top speed of 156mph - but his speedometer had reached speeds of 170mph, Truro Crown Court heard in 2009.
The court was told that Bowden was caught speeding 30 times - riding 70mph in a 40mph limit, 100mph in a 60mph limit and 124mph in a 70mph limit.
Bowden, a 42-year-old father-of-four from Helston, Cornwall, pleaded guilty to a charge of dangerous driving but escaped a jail term.
He was given a 51-week jail sentence suspended for two years, fined £190 and disqualified from driving for three years.
The prison sentence was suspended after the dead man's family asked the court to show lenience because he and Bowden had been close friends.
Judge Christopher Elwen told Bowden at the time: 'This wild ride came to an end with the tragic death of your long-time and close friend Andrew Prowse.
'What has been seen on the video was a prolonged course of dangerous driving with grossly high speeds and inappropriate overtaking.
'Motorists were alarmed and afraid for their lives. You will have to live with this for the rest of your life.
'In view of exceptionally powerful mitigation I will suspend the prison term for two years.'
Bowden, a car mechanic, had intended to take his son for a ride that day but Mr Prowse, his friend since school, arrived at his house and suggested they go for a ride.
Mr Prowse, also of Helston, then fitted his video camera to Bowden's petrol tank and the pair raced along the A30 in Tolvaddon, Camborne.
One witness told his passenger as they were overtaken by the speeding pair: 'Those idiots are going to die if they carry on driving like that'.
Minutes later Mr Prowse overtook a Ford Mondeo at 100mph, clipped a hatchback and was thrown under a van.
At an inquest into Mr Prowse's death, the couple driving the camper van, Michael and Julia Clements, said they were 'traumatised' by the accident.
Mr Clements, an artist, said: 'That scene will stay with me for the rest of my life.'
Defending Bowden, Robert Linford said: 'Nobody can punish him as much as he has punished himself. They had ridden together a lot.
'Mr Prowse was known to the defendant since their school days. They were best friends and their family were close. He must now live with the knowledge of what happened to his friend.'