All Fitbit trackers are optimized for walking, running, and general household and lifestyle activities.
It will not be as accurate for activities like biking, but will record steps if you wear your tracker.
For increased accuracy, go to http://www.fitbit.com/activities or click the "log activity" icon from your dashboard to manually log activities like cycling. This will allow for a more accurate estimated calorie burn to be included in your daily totals. Our online database of workouts makes it easy to save and access your favorite activities. For detailed information see How do I log or record an activity?