Even his fellow “Tridorks” and “Freds” are turning on him.

Cyclists are racing online to rage against speed demon Jason Marshall — and show their support for the tragic victim he mowed down in Central Park.

As Jill Tarlov, 59, remained on life support from her massive head injuries at an Upper East Side hospital, cyclists took to blogs and Twitter to jeer Marshall for slamming his $4,000 racing bike into the Connecticut mother of two on Thursday at a West Drive intersection.

Some insiders blasted Marshall as a triathlon-obsessed “Tridork,” and a “Fred,” both derogatory terms for Lycra-clad cyclists riding pricey, tricked-out bikes.

“The very worst Freds and Tridorks — in fact the very worst cyclists period — are the ones using the parks to launch their personal hour record attempts,” wrote Eben Weiss on his popular blog Bike Snob NYC.

Marshall, 31, of East Harlem, doted on his top-of-the-line Jamis Eclipse racing cycle and kept precise records on the Web site Strava.com of his blazing rides through Central Park — in which he boasted of reaching speeds exceeding 35 mph.

“There’s no reason to be doing hot laps in the middle of the g–damn city,” blogged Weiss, an author, frequent racer and former bike messenger.

“There’s a time and place for everything — and Central Park is neither,” agreed one poster who called himself “il Pirata est Mort.”

Added another poster named “dop,” “If there are joggers, roller bladers & kiddy strollers out there, you should stay around 15 mph.”

Rather than side with Marshall, the Century Road Club issued a statement saying the group’s “collective thoughts are with Jill Tarlov and her loved ones during this very difficult time . . . We know it only takes one moment of bad judgment from one individual to cause major problems for all of us.”

Bike Snob NY even started a #nostrava Twitter campaign to urge athlete bikers to turn off their Strava.com accounts for the weekend out of respect for the Tarlov family, and to “show the world that we’re not just a bunch of Lycra-clad weenies.”

“You know people are going to cross against the light and if you choose to ignore that, inevitability the blame should fall on you,” Weiss blogged.

Marshall spoke to cops and an assistant district attorney in the hours after Thursday’s bloody crash, telling cops he was only going around 8 or 9 mph when he struck Tarlov, sources said Saturday.

But at least one cyclist told police that right before the crash, Marshall blew past at around 25 mph. Doctors have told police that Tarlov “looked like she was hit by a car,” sources said.

The Manhattan DA’s office is investigating possible charges.

Marshall has since retained an Upper East Side lawyer and is declining to answer reporter questions.



Additional reporting by Kevin Fasick and Andrea Hay