Lyon's system is called Vélo'v and the pricing is €2 for every extra hour after the first free 30 minutes. Otherwise, the system closely resembles the one in Paris (see above).

BRUSSELS

(courtesy Mairie de Paris) [enlarge photo]

Despite being the headquarters of the European Union, Brussels' public bike system, called Cyclocity (cyclocity.be), only has 250 bikes available from 23 stations throughout the city. Tourists can sign up for short-term subscription cards (€1 a day or €1.50 a week) from free-standing meters at every station; rentals cost €0.50 a half hour. The sign-up, rental, and return instructions are identical to those in Paris and Lyon.

VIENNA

First you have to get a Citybike tourist card for €2 a day. Request one from your hotel or one of two "issuing offices" (Royal Tours, Herrengasse 1—3, or Pedal Power, Ausstellungsstrasse 3) . Once you have a card, you can pick up a bike from any of about 50 stations around the city, which are usually located near subway stations. The steps to picking up and returing a bike from an individual station are nearly identical to those in Paris and Lyon. (There's one small difference: Instead of waving your card in front of the terminal's screen, you have to swipe it through a slot.)

The first hour is free, the second is €2, the third costs €3; you'll be charged €4 for the fourth hour and for every hour thereafter. You can only rent out one bike per card, and the rental is limited to 120 hours after which it will be considered lost. If you lose the card, you'll be charged €10. For more information, check out citybikewien.at.

HELSINKI

During the summers in Helsinki, you can pick up a bike from any of 26 stands around the city center. All you need is a €2 coin deposit to stick in the lock, which you'll get back when you lock it back up again. (There isn't any rental time limit but you have to stay within the city limits.) Otherwise, the sign-up, rental, and return instructions are similar to the programs described above. See hel.fi for more details.

OSLO, BERGEN, TRONDHEIM, AND DRAMMEN (NORWAY)

Again, you'll need a Citybike tourist card to ride the public bikes in Oslo, Bergen, and Drammen. (Note: Their systems only operate on a seasonal basis, usually shutting down in late fall and reopening in the early spring.) City visitor information offices rent the requisite cards out to tourists.

In Oslo, though, there are some important differences. Oslo's Bysykkel program charges tourists 70 kronor, or about $10, a day. Rentals are a maximum of three hours. After three hours, you have to return it to a bicycle station, but it is possible to rent the bike for another three hours without paying an additional fee.

Note that, when biking, you must stay within Oslo's city limits. Stations will only allow you to take out bikes between 6 a.m. and midnight. They will give you merely 30 seconds to pull your bike from its stand once you've been assigned one—but they will accept bike returns 24 hours a day. (When bikes are properly returned to a stand, a little light in the lock changes from red to green.)

In Trondheim, Norway, people can use a free bike simply by popping in a small coin into the lock, which pops back out again once it's locked back up. More info for the programs in all of these Norwegian cities at adshel.no.

COPENHAGEN

Denmark's capital has 1,300 free bikes for the public to use annually between May and mid-December. All you have to do is find one of the 125 City Bike stations in the city center and deposit a DKK 20 coin (about $3) and start pedaling (staying within the city center). You'll get the coin back when you lock it back up at a City Bike station. Details here.