According to
NY Daily News, the bicyclist was originally in the bike lane, but swerved into vehicle lane only to avoid hitting some other pedestrians:
Police say Marshall, 31, was riding in the bike lane when he swerved to avoid colliding with a group of pedestrians and wound up striking Tarlov, police said.
“He was in the far left bike lane,” a police official said Friday. “When he approached the crosswalk, he swerved out of the bike lane to avoid other pedestrians and he crossed over went into the traffic lane and hit her.”
That part of the loop being the latter part of a stretch of downhill, most bikes are faster than usual, most probably coast.
One of the pictures at Daily News shows the road quite clearly, where you can see some slope.