Coach’s Corner — Is It Better to Ride a Smaller Bike?
Our Coach’s Corner series is your chance to have your biggest cycling questions answered — right from longtime cycling coach Darryl MacKenzie. In these short Q&As, Coach Darryl speaks from his 35+ years of cycling and coaching experience to help you become a stronger, smarter cyclist.
Curious Cyclist:
Coach, I see many cyclists getting bikes that are smaller than they look like they should be riding. Is it better to get a smaller bike?
Coach Darryl:
I’m noticing this trend too. More riders are showing up to bike fits on bikes that appear smaller than what their height and leg length would suggest is ideal. Recently, I worked with a cyclist who was only about 2 inches shorter than I am — yet he had purchased a bike that was four sizes smaller than what I ride. That’s about over 3 inches smaller — a significant difference!
The reason for smaller bike sizes seems to be a style choice, but I don’t recommend following the trend. The size of your bike influences how strong and fast you can pedal, how comfortable you are on longer rides, and even what repetitive motion injuries might develop over time.
Having the proper size bike supports those things. The wrong size makes them worse.
What Happens When a Bike Is Too Small?
Bike size is measured by the length of the seat tube, which runs from the bottom bracket where the petals attach up toward the saddle. As the seat tube gets shorter, the other tubes get shorter too. That means reach, body position, and weight distribution all change.
Generally speaking, the longer your legs are, the greater the distance should be between your hips and the pedals. That typically requires a larger frame.
There is an optimal position for pedaling power. At the bottom of the pedal stroke, the knee angle should be about 35 degrees (which fitters calculate as 145 degrees of bend subtracted from 180 degrees at a fully straightened leg). That angle allows for strong, efficient pedaling.
On a bike that’s too small, it becomes harder to achieve that position.
The Saddle Height Problem
Many cyclists simply set their saddle at what “looks right” and ride. On a smaller bike, that usually means the saddle is too low.
To reach proper saddle height on a small frame, the seatpost must be extended farther out of the seat tube. But there is a minimum insertion requirement for safety. If the seatpost isn’t inserted deeply enough, you risk breaking the seatpost or frame.
If the seatpost isn’t long enough to safely achieve proper height, I have to pause the bike to source a longer post. That adds time and expense — all to compensate for a frame that may be too small.
Power and Knee Stress
When the saddle is too low, the knee angle increases beyond the ideal 35 degrees.
I tell riders that a 45-degree knee angle has a technical name: terrible.
A 55-degree angle is horrible.
Why? Because you’re not reaching full leg extension at the bottom of the stroke, where your legs generate the most power. Instead, you spend more of the pedal stroke in the upper range, where less power is available. You’ll really notice that power shortage when climbing — especially when riders who aren't as strong as you start to pass by.
A low saddle also increases pressure on the front of the knee and is often associated with anterior knee discomfort and long-term repetitive motion problems.
Knee Position and Frame Length
A smaller frame also has a shorter top tube — the tube between the saddle and handlebars. That typically places the rider farther forward.
Ideally, when the pedals are level, the knee of the forward leg should sit 1–2 centimeters behind the center of the pedal spindle. This allows the leg to push slightly forward during the power phase.
On a bike that’s too small, the knee often ends up too far forward. That shifts the force backward, reducing power and again increasing stress on the front of the knee. In some cases, the saddle simply cannot be moved far enough back to correct this without replacing components.
Handling and Safety Concerns
There’s also the issue of weight distribution.
On some small bikes I’ve fitted, the rider’s body was positioned so far forward that their nose was actually ahead of the handlebars. That moves the center of gravity forward, which can compromise braking and cornering and increases your risk of going over the handlebars.
The Coach’s Bottom Line
A smaller bike might look more aggressive and save a few grams. But it can cost you power, comfort, control, and potentially long-term knee health.
Bike fit is about optimizing what your body can do, not forcing your body to adapt to a frame that doesn’t match your proportions.
Smart cyclists choose a bike size that supports strength, efficiency, and longevity — not just appearance.
Photo by Andrea Piacquadio on Pexels
