Know what to ride today.
Watt4 is an AI coach for cyclists and runners who already ride plenty and want it to add up to something. It reads every session you have ever done, tells you what to do next and why, and rewrites the week the moment life gets in the way.
Free while we are building. No card. Connects to Strava, Garmin, Wahoo and Zwift.
Form has been climbing for nine days and the race is four weeks out. Tempo keeps the top end honest.
Why this session
“Two tempo blocks keep the top end honest without leaving fatigue you would carry into Friday.”
Reads and writes to Stravasends workouts to GarminWahooZwift
The honest problem
You don’t need a plan. You need someone paying attention.
Every ride becomes the same ride
Not easy enough to recover from, not hard enough to change anything. Week after week lands in the middle, and the middle is where fitness goes to sit still.
The plan broke in week two
A downloaded twelve-week block has no idea you travelled Thursday, that the club ride went long, or that you woke up wrecked on the day of the intervals.
You can’t tell if it worked
Six weeks of effort and no honest answer to the only question that matters: are you actually fitter, or just tired in a more organised way?
Today
The session, and the sentence that explains it
Every recommendation arrives with what it is for, why now, and what it is protecting. You are free to disagree — but you will know exactly what you are disagreeing with.
Endurance + 2 × 12 tempo
Today · Tuesday 22 September · bike
“Your form has been climbing for nine days and the gravel race is still four weeks out. Two tempo blocks keep the top end honest without leaving fatigue you would carry into Friday.”
How it works
Three steps, and the third one is just riding.
Connect what you already use
Strava, Garmin or Wahoo. Watt4 pulls your whole history — every ride, every run, the entire power curve — in one go.
It works out your numbers
FTP, threshold pace, fitness, fatigue and form, estimated from what you have already done — each with how much to trust it stated out loud. No test required to start.
Ride what it tells you
A session each morning with the reasoning attached, built as a structured workout and pushed to your head unit before you get changed.
The week
A week that bends instead of breaking
Travelling Thursday? Say so. Club ride on Saturday you were never going to skip? Add it. Watt4 moves what matters, drops what doesn’t, and tells you in plain words what it did and what it cost.
After the ride
It marks the ride, not just records it
Every activity imports and gets scored against what was planned. Did you hold the tempo blocks, or did the group ride happen to you? The verdict goes back to Strava so it sits with the activity itself.
Both tempo blocks landed within 3W of the 246W target. Heart-rate drift across the second block was the smallest in six weeks.
The last 20 minutes ran at 89% when the plan said endurance — that is where the extra 9 TSS came from.
The coach
A coach you can argue with
Tell it you are ill, that your FTP is 280, that Friday no longer works. It has your whole history in front of it, so you never explain yourself twice — and it changes the plan while you are still typing.
Did a 20 minute test this morning. Averaged 295.
That puts your FTP at 280W, up from 268W. Your zones have moved with it — today’s tempo blocks are now 246–258W.
Your numbers
It tells you what your training is actually doing.
Fitness, fatigue and form over twelve weeks. A threshold estimate that admits how much to believe it. And a ranked read on what has changed lately, where every line is something you can act on.
Insight 1
Your tempo work is sticking
Power at 88–92% FTP has held for three weeks while heart rate at the same effort dropped 4bpm.
Insight 2
Weekly volume has gone flat
412 km three weeks running. The event you picked asks for one bigger week before you taper.
Insight 3
You are losing the easy end
38% of last week sat in zone 3. Your endurance rides drift up whenever you ride with the group.
Events
Training for something specific?
Point Watt4 at an event — a gravel race, a first 100 km, a spring marathon — and it plans backwards from what that day actually demands. Then it tells you honestly how ready you are and where the gap is, which is rarely where you assumed.
Your three-to-five hour endurance is there — four rides over 3h in six weeks. Repeated three-minute climbs are the gap, and four sessions are already planned before the taper.
Questions worth asking
Is it really free?
Yes. No card, no trial timer, no feature held back. Watt4 is early and riders using it are worth more right now than revenue.
Do I need a power meter?
No. Power makes the estimates sharper, but heart rate works and running is planned on pace throughout. You can start with whatever your watch already records.
What if I miss a week?
Nothing breaks. Watt4 re-plans from where you actually are rather than where a plan said you would be — and it will tell you what that costs rather than quietly pretending it is fine.
Does it handle running too?
Yes. Run sessions are built on your threshold pace, and if you do both sports it plans them as one training load instead of two that ignore each other.
Where do the workouts end up?
Garmin, Wahoo or Zwift, pushed straight to the device. Or a .fit file you can put wherever you like.
Who is behind it?
A developer in Belgium who rides road and gravel, got tired of guessing what to do on a Tuesday, and built the coach he wanted.
Start with the ride you were going to do anyway.
Connect Strava and Watt4 will have your numbers, your zones and your first session ready before you have finished your coffee.
Takes about two minutes. Nothing to cancel later.