The wheel diameter of 26 inches mountain bike is about 673mm, and the diameter of the rim is 559mm.
The 27.5 inches mountain bike has a wheel diameter of about 698 mm and a rim diameter of 584 mm.
After installing an outer tire, the wheel diameter of 29 inches mountain bike is about 736 mm, and the diameter of the rim is 622mm.
26 inches is the most traditional mountain bike wheel diameter. The wheel diameter of early mountain bikes was all 26 inches. Until now, many manufacturers are still producing 26 inches wheels for mountain bikes. Because it has the advantages of light weight, low center of gravity, good stability, excellent handling, but slightly worse on passability.
In recent years, the 29 inches mountain bikes have become popular among cycling enthusiasts. The large wheel diameter allows for better passability when crossing gullies on off-road riding. However, large wheel diameter means heavy weight, riding on flat road and climbing are laborious, and the handling is poor.
To balance handling and passability, some manufacturers have appropriately reduced the wheel diameter of 29er and introduced the 27.5 inches (650B) mountain bike. Its climbing performance is close to 29er, downhill performance is relatively poor, but the rider’s riding position is more natural and relaxed.