You're getting fitter if you can do more work before feeling the same, and recover faster afterward. You don't need a lab to see it. The same climb at a lower heart rate. Longer rides that leave you less wrecked. A fitness number that trends up over weeks, not days. If those are moving, you're moving.
Riders have always measured fitness without instruments. Faster up the climb you know by heart. Hanging with the group that used to drop you. "Six months ago I could barely do ten miles, and Saturday I did thirty." Those instincts are right, and they're right for a reason: they're all repeatable tests. Same course, same you, different result. That's the definition of getting fitter.
The catch is they're occasional. You don't ride the benchmark climb every week, and memory is a generous narrator. A good fitness number is just those folk tests made continuous: every ride measured, the trend visible.
It's a rolling trend of your honest per-ride effort over about six weeks. Not a score for today. A trajectory. This is how RideTool computes fitness: every ride gets an effort score in one currency, from power where power is honest and from heart rate where it isn't, and fitness is the long-term trend of those efforts.
One rule for reading it: single rides are noise, the trend is signal. A monster Saturday doesn't make you fit and a skipped week doesn't make you unfit. Look at the last four weeks against the four before them. That comparison is slow to fool and slow to panic, which is exactly what you want from a number you're going to make decisions with.
Some days you're fitter than ever and your legs feel like sandbags. That's fatigue sitting on top of fitness, and the two are different numbers. Fitness is the slow trend of your training. Freshness is how recovered you are right now, and it swings in days. After a big week, freshness tanks while fitness quietly rises. This is why RideTool shows both, in plain words with the reasons. When you know the flat feeling is fatigue, you rest instead of concluding the whole spring was wasted.
Steady weekly riding moves fitness slowly and surely. Ride a few times a week, every week, and the trend climbs at a rate you'll barely notice day to day and can't miss month to month. Weeks to build, days to lose.
Be suspicious of big jumps. If a number claims you got dramatically fitter in ten days, the number is wrong, because bodies don't work that fast. The honest shape of progress is a slope, not a staircase. It's less exciting to look at and much better to stand on.
Here's the part I wish someone had told me sooner: fitness lost over months comes back in weeks. The first rides back feel terrible and the numbers look worse, and that's exactly when most comebacks die. But the trend turns fast once you're consistent. Ride three or four times a week and in a month the same loops feel different. In two, the chart is unambiguous.
I built RideTool partly for this moment, because the comeback is where you most need proof that the work is landing before your legs believe it. The number climbs when you ride and slips when you don't, and watching it climb is what keeps you going out. So the real answer to "am I getting fitter?" is: ride steadily for six weeks and the question answers itself. Just keep riding.
Connect Strava, Garmin, or Wahoo and RideTool turns every ride into a plain-English read on your fitness. Three short emails a week tell you if the riding is working. $29 a year, no ads, your data stays yours.
Start with your next ride