Marshall, a studio session saxophonist, told cops he couldn’t say how fast he was pedaling down the park’s West Drive when he slammed into Tarlov, source said.
“We don’t know how fast he was going,” one frustrated investigator conceded Friday night.
But Marshall, 31, of East Harlem, likes to go very fast — and boasts about it online almost every day.
He uses a GPS and other software to track his maximum and average speeds during his often twice-daily rides through the park, The Post has found.
His blazing speeds are uploaded — precise to the 10th of a mile per hour — onto a competitive running and cycling Web site.
“New Chain, brakes and RD(7800gs),” he had boasted earlier Thursday on the Strava site, referring to a new rear derailleur for his bike. “All systems go.”
Hours before he slammed into Tarlov, Marshall had logged 32.2 miles of cycling during a predawn spin through the park, the site says — and listed his top speed for that ride at 35.6 mph, well over the 25 mph speed limit for bikes and cars.
His maximum speed during five sprints on that same downhill stretch of West Drive during his Thursday-morning ride was 28.9 mph, his data on Strava says.
Marshall — who appeared to have logged every one of his 9,000 miles ridden so far this year — left no record of the one afternoon ride that put Tarlov in the hospital.
After the crash, he admitted to cops he was in the wrong lane but insisted he wasn’t speeding, had the green light and had shouted to warn Tarlov as he approached, law-enforcement sources said.
But so far, witnesses have told cops that Marshall appeared to be going at a high rate of speed and had tried to swerve rather than brake.