Short answer
Most space efficient full body option: an air rower (Concept2 lists a 108 x 48 inch operating area, and it splits for storage). Hardest intervals: an air bike, but the fan is loud. Quietest: an indoor cycling bike. Treadmills take the most room and need the safety key removed around children.
Compare by space and noise
Cardio machines compared
| Machine | Floor in use | Noise | Works |
|---|---|---|---|
| Air rower | 108 x 48 in (Concept2) | Moderate fan whoosh | Legs, back, arms |
| Air bike | Bike size | Loud fan | Legs and arms together |
| Indoor cycling bike | Smallest | Quiet | Legs |
| Treadmill | Largest | Motor plus footfalls | Walking and running |
Concept2 lists the RowErg’s operating area as 108 x 48 inches and its weight as 57 lb with standard legs (Concept2 specs).
Machines to compare
-
01Rower
Concept2 RowErg with PM5
Best for: Full body cardio that stores away
- Monitor
- PM5 (listing)
- Storage
- Splits in two (Concept2)
-
02Air bike
Schwinn AD6 Airdyne
Best for: Hard intervals with arms and legs
- Resistance
- Rises with effort (fan)
- Frame warranty
- 15 years (listing)
-
03Quiet
Brake pad indoor cycling bike
Best for: Shared walls and small rooms
- Capacity
- 350 lb (listing)
Treadmill safety
Want to try a treadmill before buying? Utah showrooms carry them. Used treadmills need a longer test: see the checklist.
Questions people ask
What is the best cardio machine for a small space?
An indoor cycling bike has the smallest footprint in use. A rower is long in use but stores upright or in two pieces; Concept2 lists the RowErg’s stored size at about 25 x 33 x 54 inches.
Which cardio machine is quietest for an apartment?
A magnetic or brake pad indoor cycling bike. Fan bikes and air rowers move air and are louder; treadmills add footfall noise through floors.
Are treadmills dangerous for kids?
They can be. In 2021 the CPSC warned that children can be pulled under a treadmill belt and urged owners to keep children and pets away and remove the safety key when not in use. CBS reported a CPSC estimate of about 2,000 treadmill injuries to children under 8 in 2019.
Sources
Last reviewed October 29, 2026. Store hours, listings and models change; call a store before you drive and follow the maker’s instructions for setup and weight limits.