A cyclist who was trying to break his own speed record for a stretch of road has been charged with manslaughter after he smashed into a pedestrian and killed him.

Chris Bucchere was travelling at over 35mph in a 25mph zone in San Francisco when he hit 71-year-old Sutchi Hui, who was crossing the road. He could now face up to six years in jail if found guilty.

The San Francisco Examiner reports that Bucchere has now been charged with felony vehicular manslaughter. The charge was elevated from a misdemeanor because Bucchere had allegedly violated multiple laws prior to the collision, which shows gross negligence, District Attorney George Gascón said.

Bucchere was riding with a friend from Marin County to San Francisco, and an examination of his GPS unit and CCTV from a local shop confirmed his speed before the incident. Crucial to the charges, say prosecutors, is the fact that his riding partner managed to stop without hitting anyone.

We reported a couple of months ago how Bucchere had apparently taken to the web following the crash, and sparked outrage after he described the incident and lamented the fact that his helmet had been broken.

"I was already way too committed to stop," the post, which was made by a user named ‘Bucchere Chris’ from an account linked to Mr Bucchere’s email address, said. "The light turned red as I was cruising through the middle of the intersection and then, almost instantly, the southern crosswalk on Market and Castro filled up with people coming from both directions... I couldn't see a line through the crowd and I couldn't stop, so I laid it down and just plowed through the crowded crosswalk in the least-populated place I could find."

It went on to say that the bike helmet "died in heroic fashion today as my head slammed into the tarmac. ... May she die knowing that because she committed the ultimate sacrifice, her rider can live on and ride on. Can I get an amen? Amen."

The prosecutors say that their decision was not based on these comments, however.

Some 4,834 cyclists and 59,925 pedestrians were killed by motor vehicles in the United States between 1999 and 2009 (the most recent year for which figures are available), according to the Centers for Disease Control and Prevention. Cyclists killed just 63 pedestrians, or about six a year, during the same time period.

Although this type of incident is rare, it has led to calls from campaign groups to better protect pedestrians from cyclists.