Last August, Citi Bike introduced 200 pedal-assist e-bikes into their 12,000-bike fleet as part of a pilot program. Not surprisingly, technology that giddily propels you up steep hills with very little effort proved to be enormously popular: normal CitiBikes saw five rides per day, while the electric models got 15 rides in before their batteries conked out. Beginning today through end of spring, Citi Bike says they will introduce 4,000 new pedal-assist e-bikes into their fleet.

The juice is gonna cost you: $2 per e-bike ride, starting on April 27th. For reduced fare members, it will be an extra 50 cents. An unlimited number of 45-minute rides on the "classic" bikes will still be included in a membership, according to a press release.

Under this pricing scheme, a Citi Bike commuter who wants to use an e-bike to get to and from work every day of the year would pay an extra $1,000 on top of their $169/year membership. Cheaper than an unlimited monthly MetroCard, but less useful.

Citi Bike will waive the fee for certain stations along the L train corridor during reduced service hours (and given the current state of the L train repairs, there could be a lot of them). In the unlikely and amazing event that a rider finds only e-bikes at a dock, they will not be charged the $2 fee.

Citi Bike spokesperson Julie Wood says the increased costs are necessary to expand the system, ensure it's sustainable, and to hire more employees to travel from dock to dock and replace dead batteries with fresh ones. The 750 docking stations citywide aren't strong enough to charge the batteries themselves because they run on solar power.

"What we’re seeing is, e-bikes are really going to compete with other modes of transportation," Wood told Gothamist. "What was a subway ride, a taxi ride, a ride in a Lyft, can now be an electric bike ride." (Lyft bought Citi Bike last summer). Wood said that unlike the pilot, these e-bikes will soon be "a very reliable new option for people."

Once Citi Bike figures out how people use the new e-bikes, the company will introduce some new membership options in the spring that may include a certain number of e-bike rides in a yearly membership. Look for another 2,500 docks to be installed over the next few months as well.

While the "vast majority" of Citi Bikes won't be electric, by the beginning of the summer, the company says it will have 13,000 bikes, 4,000 of them pedal-assist. That number is supposed to jump to 40,000 bikes over the next five years, covering 35 miles of New York City (and parts of New Jersey).

Citi Bike's e-bike expansion comes as the City Council is attempting to legalize throttle e-bikes, which are cheaper than pedal-assisted e-bikes and popular with New York City's immigrant delivery cyclists. The delivery cyclists receive fines and have their bikes taken from them for utilizing what is essentially the same technology.

Asked if Citi Bike supports the legislation package, the company pointed to a blog post published on Medium by Caroline Samponaro, the head of bike, scooter, and pedestrian policy at Lyft.

"We also believe in sensible regulations around electric bikes that make them available to everyone who needs them, including working cyclists in New York City," Samponaro wrote.