650B VS 700C Bike Wheel Size
At the most basic level, 700c wheels have a larger diameter (622mm) than 650b wheels (584mm). 700c has long reigned as the default wheel size on the majority of road, gravel and cyclocross bikes. 650b has recently seen a resurgence in popularity from its heyday on 20th-Century French bicycles.
With that said, you may be wondering about the characteristics of the two sizes, and which one suits your riding style.
The 700c wheel and tire combo offers less rolling resistance, gathers more momentum and has better rollover capability than 650b wheels with higher-volume tires. For some, these may be the go-to size for riding on pavement for commuting, training rides or racing on hero gravel.
The smaller diameter of 650b wheels allows you to run higher-volume tires within the same frame. Because higher-volume tires are taller than the tires you could run on a 700c wheel, the wheel and tire diameter end up being similar to a 700c wheel and road tire setup. This means that handling characteristics and geometry are minimally affected by the wheel change, yet you gain the benefits of a higher-volume tire.
So why smaller wheels and higher-volume tires? Higher-volume tires create a larger contact patch, which allows for more grip when cornering, accelerating and braking. Bump absorption is also improved, which cuts fatigue on long rides or rough terrain.
An added bonus for shorter cyclists: 650b wheels are more proportional to small frames, and can reduce toe overlap and top tube height for better standover clearance.
Many riders choose 700c wheels for riding on pavement or racing on gravel surfaces. To soak up the bumps on rougher roads and unpaved surfaces, 650b wheels and large tires might be a good choice—especially if you ride a smaller frame.
Source: Salsa Cycles