Citi Bike has been compiling daily stats on usage and membership on its blog, and in the 24 hours between 5 p.m. Tuesday and 5 p.m. Wednesday, users logged 7,500 trips on the bike-share system. The number of annual members increased by nearly 2,000 over the same period, bringing the total to 21,300.

Joe Cutrufo at the Tri-State Transportation Campaign dug up some usage stats from the early days of bike-share in Boston and DC, and it looks like the number of trips per bike in NYC is slightly outpacing both of the other cities. In the first two full 24-hour periods that we have data for in NYC — from Monday at 5 p.m. to Wednesday at 5 p.m. — Citi Bike users made 14,930 trips, which works out to about 1.24 trips per bike per day. Meanwhile, Cutrufo reports that when DC’s Capital Bikeshare launched in 2010, users made about 1.05 trips per bike per day in its first 10 days.

CaBi launched later in the year than Citi Bike, and it didn’t have as much hype, but let’s extrapolate a bit anyway. This April, CaBi users made about 8,000 trips per day on a system with around 1,800 bikes, for about 4.4 trips per bike. If NYC maintains a slightly higher rate of trips per bike, a Citi Bike network with 10,000 bikes would see more than 50,000 trips per day during the peak biking months.