NICTD has removed half the seats from three South Shore cars, and one quarter of the seats from four others. That will allow 26 bikes on the former and 14 on the latter.

Noland said the total number of spots available for bikes on all trains through the course of the summer will be 130,000. Train cars with bike racks will be designated by a decal.

"We believe we're going to be able to meet the demand, but we don't know," he said, acknowledging that demand levels can't be predicted. "We're putting our toe in the water."

All standard bicycles will fit the racks, Noland said. The racks hold bikes at a 45 degree angle, and are "about as easy to use as can be," he said.

Fourteen of the 18 weekend trains will accommodate bicycles. Westbound, those include the trains arriving at Chicago's Millennium station at 7, 9:13 and 10:16 a.m., and 2:39, 5:23, 7:11 and 11:43 p.m.

Eastbound, trains with bike-ready cars include ones leaving Millennium station at 8:40 a.m. and 12:12, 1:35, 6:22, 9:15 and 11:15 p.m. and 12:45 a.m.

Noland said NICTD is ready to expand the service.

"At some point in time I'm sure we're going to be asked to consider off-peak service," he said, referring to non-rush hour weekday trains.