A road bicycle is 10 to 30% faster than a mountain bike and is 15% faster on average at the same power output on smooth, paved surfaces.

• Riding posture, rolling resistance, frame geometry, and weight are the main reasons for road bikes being faster with the same level of effort.

Riding position & speed

The greatest determining factor of speed over 8mph (13 kph) is riding position.

• Cycling in an upright posture, as you would on a mountain bike, can be twice as slow as being tucked down while riding in the drops. The faster you go, the larger role aerodynamics and riding position have on your speed.

Rolling resistance: MTB vs Road

The interaction between the tire and terrain is known as rolling resistance. Rolling resistance is affected by:

• Tire Width

  • Wider tires have more contact with the terrain and are slower and heavier

• Tire Pressure

  • Less pressure increases contact with the ground and thus are harder to pedal (slower). As tire pressure increases, the tire holds its shape more firmly, which reduces tire deflection

• Tread Type

  • Larger tread is slower

• Wheel Diameter

  • Smaller diameter tires at the same pressure are easier to deform, making them slower

All of these make larger, knobbier, low-PSI, and heavier mountain bike tires slower than the sleek and narrow road bicycle tires.

Weight difference between bikes: Road Vs MTB

For every 12 pounds gained or lost there is a 1-mph difference in speed. A full-suspension mountain bike will usually weigh at least 12 more pounds than a road bike.

• Full-Suspension MTB = ~ 30 lbs

• Road Bicycle = ~ 17 lbs

Just from the weight factor alone, a road bicycle will be at least 1 mph faster compared to the heavier mountain bike.

Frame geometry differences: Road & MTB

Road and mountain bikes have vastly different frame geometries, which affect both aerodynamics and pedal efficiency.

• Road bikes place you in a more optimal position for pedaling while trail bikes focus on rider stability for descending technical singletrack.

• Mountain bikes are engineered to be sturdy while maximizing clearance and control. Road bikes are designed to maximize aerodynamics and pedaling economy

Gearing

Most mountain bikes, especially trail bikes, are geared for climbing and riding off-road, which is why they lack big gears. Road bikes are designed with a broader range of gear combinations. Once you reach high speeds on smooth surfaces, the difference in gearing becomes obvious.

Jesse is Director of Pedal Chile and lives in Valdivia, Chile. Jesse has a Master of Science in Health & Human Performance and a Bachelor of Science in Kinesiology. Hobbies: MTBing, snowboarding, reading, taster of craft beers, and researcher.

More articles from Pedal Chile

Sources

• Chowdhury, Harun & Alam, Firoz & Khan, Iftekhar. (2011). An experimental study of bicycle aerodynamics. International Journal of Mechanical and Materials Engineering. 6. 269-274.

• Glaskin, Max. Cycling Science: How Rider and Machine Work Together. Ivy Press, 2019.

• Petersen, Grant. Just Ride: a Radically Practical Guide to Riding Your Bike: Equipment, Health, Safety, Attitude. Workman Pub., 2012.