Spin or Grind? Ask Your Run Split.

A cyclist asked me what cadence he should ride at. I asked him what he was doing after the bike.

He looked at me like I had misheard the question. He was a cyclist. Nothing came after the bike.

For him the answer is one thing. For a triathlete it is a completely different conversation, and that is the part most cadence advice misses, because most cadence advice was written for people who get off the bike and go home.

In a triathlon, cadence is not a cycling decision. It is a decision about which muscles you want to be tired.

The Actual Trade

At any given power you can produce it with high force and low cadence, or lower force and high cadence. Same watts, different route.

Grinding, roughly seventy to eighty revolutions, means higher force per pedal stroke. That loads the muscular system, particularly the quads, and it is mechanically efficient in the narrow sense that you waste less energy moving your legs around.

Spinning, roughly ninety to a hundred, means lower force per stroke and more strokes. That shifts the cost toward the cardiovascular system and away from the muscle.

For a standalone cyclist, either can be correct and most self-select somewhere sensible without being told.

Why the Run Changes the Answer

Here is what I actually care about. Your legs have a finite amount of muscular work in them on any given day, and the run is going to ask for a large share of it.

If you grind for three hours, you arrive at T2 with quads that have done a great deal of high force work. Then you ask them to run, which is also high force, and they have nothing. That is the athlete who feels fine on the bike and falls apart in the first five kilometres.

If you spin, you have spent more on your cardiovascular system, which recovers faster during the transition and which the run does not tax in the same way. Your legs are less chewed up.

So for most triathletes, most of the time, I want a slightly higher cadence than they would naturally choose, and I want it because of the run rather than because of the bike.

The other reason is neuromuscular. Riding at eighty five to ninety five is closer to the rhythm of running than riding at seventy is. The transition asks your nervous system to change tempo, and a smaller change is a faster one. That is why the ugly first kilometre off a low cadence ride tends to last longer.

What I Actually Prescribe

Somewhere around eighty five to ninety five for most athletes on the flat in a race. Not a hundred, unless that is genuinely natural to you, because very high cadences carry a cardiovascular cost of their own and can spike heart rate in a way that is unhelpful over hours.

On climbs, let it fall. Trying to hold ninety up a real hill either means an unrealistic gear or a power spike, and both are worse than accepting seventy for two minutes.

And in the last ten minutes before T2, deliberately raise it. Higher cadence, lower resistance, easier gear. You are pre-loading the leg speed for running and flushing some of the accumulated load. This costs you almost nothing in time and it is the single most effective thing I know for making the first kilometre off the bike feel normal.

The Caveat

Self-selected cadence is not arbitrary. Riders converge on something efficient for their own physiology, muscle fibre distribution and limb length, and forcing a large change is usually counterproductive.

So I do not take somebody riding at seventy five and tell them to ride at ninety five. I take them to eighty, then eighty five, over a couple of months, with high cadence work built into their sessions. Five to ten percent at a time, and let it settle.

And if an athlete rides at ninety five naturally and runs beautifully off the bike, I leave them entirely alone. The evidence you actually care about is not the number on the head unit. It is the first kilometre of the run.

How to Test It on Yourself

Two bricks, two weeks apart, same route, same power. One ridden at your normal cadence, one ridden five to eight revolutions higher. Then twenty minutes running at race pace off each.

Compare the run, not the ride. Pace at a given heart rate, how the first kilometre felt, and whether you held form to the end. That is your answer, and it is yours rather than a general rule.

The Bottom Line

Ride a little higher than feels natural, let it drop on the climbs, and spin easy for the last ten minutes before T2.

Then judge it by your run split rather than by anything the bike computer told you.