Sacramento is flat and on a grid, which makes it one of the most cycle-friendly cities in California. The city has hundreds of kilometres of bike lanes and the American River Parkway provides a car-free corridor east to Folsom. Bike-share (JUMP/Lime) is widely available downtown and in Midtown.
The Sacramento Regional Transit light rail system covers the major corridors — the Gold Line runs east-west from the airport through downtown to Folsom, and the Blue Line runs north-south from Citrus Heights to Cosumnes River College. Light rail is useful for airport access and reaching the outer suburbs; most central attractions are walkable or accessible by bus.
Walking is the best way to explore Old Sacramento, Midtown, and the Capitol area. The three clusters are each compact and internally walkable, though the distances between them require a bike or transit. The downtown core is less walkable than Midtown — it empties out after business hours and can feel lonely at night.
Rideshares (Uber, Lyft) are plentiful and cheap by California standards. Car rental is worthwhile if you plan to explore the Gold Country towns to the east.