Gritmo started as a personal project. I wanted to understand myself better as a rider and make sense of the gaps I kept running into with models built around a single threshold, such as FTP.
As the research deepened and the implementation took shape, Gritmo became more than a rider profile. The same understanding of a rider could connect the whole experience: explain a ride, guide training, plan the effort for a race or personal-best attempt, build the right workout, and turn a course into a trainer session. That is when the project became a product.
Free at the core
Gritmo will remain entirely free to use for the foreseeable future while it develops with the cycling community.
A large part of the product can already be used without an account. An account is required only when Gritmo needs to store personal data safely, or when a feature carries a real per-use infrastructure cost and needs basic usage limits.
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One rider, one foundation
The rider model begins with Critical Power and above-CP work capacity. Durability and Repeatability join only when your rides provide enough evidence to support them.
Definitions
Critical power (CP)Critical power (CP)
The boundary above which fatigue cannot stabilize and modeled W′ begins to drain.
CP is not exactly FTP, 60-minute power, or a promise of indefinitely sustainable power.
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Above-CP work capacity (W′)
The finite amount of modeled work a rider can perform above CP.
W′ is not a literal tank, a single substrate store, or a purely anaerobic reserve.
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Durability
Ability to preserve performance after accumulated fatigue.
Without relevant late-Ride evidence, Durability is unknown—not weak.
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Repeatability
Ability to reproduce hard efforts.
A large W′ does not automatically imply strong Repeatability.
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The same foundation can then help Gritmo understand what happened in a ride, plan effort across a course, and guide training around the rider rather than a generic percentage.
What that means
Your evidence shapes the rider model. The rider model shapes what Gritmo shows and recommends next.
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Evidence
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Rider model
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Profile
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Decisions
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Built around evidence, not certainty
Gritmo separates what the rider has actually done, what the model can reasonably estimate, and what there is not yet enough evidence to say.
Observed stays observed
Recorded efforts remain evidence points. Modeled curves are shown as estimates.
Unknown is not weak
Missing evidence limits what Gritmo can say; it does not become a weakness in the Profile.
Complexity must earn its place
A new variable belongs in the rider model only when it improves understanding or action.
Gritmo is still being built. The product, the model, and these explanations will change when better evidence or better engineering gives us a reason to change them.