Complex sentence: Access for 24 hours or 7 days can be purchased, and cycles rented at any time during the period; use for not more than 30 minutes at a time is free of charge.
Split into simpler sentences: Access for 24 hours or 7 days can be purchased. Cycles may be rented at any time during the access period; use for not more than 30 minutes at a time is free of charge.