As long as you are somewhere between 80 and 100 RPM, cycling cadence probably does not matter. That is the short answer. But there is an important nuance for triathletes that the research often misses.
Why the Research Is Misleading
Most studies conclude that cadence has no impact on 20-minute power output. And that is probably true - over 20 minutes. But most triathletes are not trying to improve over 20 minutes. They are trying to sustain effort for multiple hours and then run off the bike.
The Problem With Low Cadence Over Long Efforts
Lower cadence means higher torque per pedal stroke. Higher torque means more muscle damage per revolution. Over a 20-minute effort, this difference is negligible. Over a four-to-six-hour bike leg followed by a half marathon or marathon, it compounds significantly.
The muscle damage accumulated from grinding at low cadence across a long ride directly affects your ability to run afterwards. This is the part that 20-minute lab tests do not capture.
A Simple Session to Fix Low Cadence
If your natural cadence sits below 80 RPM, this session should bring it into the right range within about four weeks. Include it once per week, inserted into one of your aerobic midweek rides.
8 x 1 minute at tempo intensity, 110 to 120 RPM, with 1 minute recovery.
Do this in your time-trial position if that is relevant to your event. Focus on staying smooth and minimising any bouncing. The goal is to make higher cadence feel natural rather than forced.
Every athlete who has been given this session has had their cadence comfortably inside the 80s within a few weeks.
Cadence does not matter over 20 minutes. But you are not racing for 20 minutes - and your run off the bike will thank you for spinning faster.