Endurance data, read against what is possible
Digital EPO: Strava Data Tools, Plausibility Checks and GPX Audits
Instruments that reconstruct what a recorded performance demanded, and a reference for the platforms that do the recording.
Endurance sport runs on numbers that almost nobody inspects. A segment time, a climbing rate, a power figure and an elevation total are read as facts, when each is the output of a device making estimates under difficult conditions. Most of the time the estimates are good. Sometimes they are not, and it shows.
Digital EPO exists to inspect them. The instruments below take figures that any public activity already displays, or a file you hold yourself, and report what those figures require of the person who produced them. Where a result exceeds what a human body can supply, they say so and leave the reason open.
Every reading is endurance data pushed back through the physics that produced it. That is the whole method, and it needs no account on any tracking platform, no upload and no permission of any kind, because the handful of figures a public activity already displays is enough to work backwards from.
Strava data tools: read a result, or read a file
- 01
Strava plausibility check
Distance, time, climbing and rider weight go in. Implied watts per kg, VAM and a verdict against the professional ceiling come out. No file and no account needed, because the figures are the ones already on the screen.
→ - 02
GPX and TCX file audit
Drop in your own activity and the parser walks every recorded point, reporting elevation spikes, position jumps, impossible accelerations and gaps. The file is read in the browser and never uploaded anywhere.
→ - 03
Watts per kg calculator
For when the power number is already known. Converts watts and body mass into relative power, then places the result on the duration-adjusted scale that decides whether a figure is strong, elite or outside the record.
→ - 04
VAM calculator
Vertical metres per hour, the one climbing measure that compares cleanly across riders, bikes and disciplines. Useful precisely where aerodynamic assumptions are weakest and gravity does nearly all of the work.
→ - 05
Cycling FTP calculator
A twenty-minute or ramp test converted into threshold power, placed on a chart by ability, and set against the way sustainable power changes across a riding career.
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What digital EPO was, and why the name still fits
From about 2013 this address carried a satirical tool. It read a Garmin device or a TCX file, raised the speed stored inside it by a chosen percentage, and returned the altered file ready to upload. The cycling press covered it widely, and forum threads argued about what it implied for segment leaderboards.
The joke worked because it was pointed. Nothing about a tracking platform can confirm that a file describes something that happened. It records what a device reports, and a device reports whatever it is handed. That gap was the target of the satire, and the gap has not closed since.
The tool is gone. Digital EPO now works that same gap from the other side: if a file can be made to say anything, the defence is to check whether what it says is possible. The instruments here do that arithmetic openly, with their assumptions printed alongside the result instead of hidden inside it.
The original pages are kept in the archive: the earlier build that altered heart rate and climbing too, the argument the satire was built against, and the parody brand page that ran alongside it.
How a tracking platform records your endurance data
Why a ride gets flagged
A flag is a data state, not an accusation — and the appeal runs through the file, never the comments.
Flags · 5 min
→Why your climbing total is wrong
Gain only sums upward, so sensor noise can never subtract. A flat ride grows a climb of two hundred metres.
Elevation · 4 min
→How KOMs are actually verified
Less runs automatically than most riders assume. The rest depends on somebody local noticing.
Segments · 5 min
→Multipath, drift and phantom sprints
A reflected signal puts you through a wall, confidently — and the accuracy readout stays healthy while it happens.
GPS · 5 min
→Estimated against measured power
Within a few percent on a steep climb; a statement about the assumed drag area on the flat.
Power · 5 min
→Getting your data back out
The bulk archive returns what your device wrote. The per-activity download quietly throws the power away.
Export · 4 min
→About this site
What is DigitalEPO?
A reference and a set of instruments for endurance data. The tools reconstruct the power a recorded result demands and inspect activity files for recording faults. The written side explains how a tracking platform measures elevation, verifies segment times and decides that something needs a second look before it ranks.
What was the original digital EPO tool?
Between roughly 2013 and 2016 this address hosted the satirical digital EPO tool. It accepted a Garmin device file or a TCX upload and inflated the speed recorded in it, so the altered file could be sent to a tracking platform. It was widely written up in the cycling press at the time.
Does anything here still alter activity files?
No. Nothing on the site writes to a file, and no upload leaves the browser. The GPX audit parses an activity locally and reports only what it finds. The direction of the work is the exact reverse of the original tool: these instruments exist to identify data that cannot possibly be right.
Is a flagged result an accusation?
It is not. The instruments report what a set of figures implies and where that sits against recorded human performance. Errors in distance, elevation, weight entry or device recording produce impossible numbers far more often than deliberate manipulation does, and none of them can be told apart from the outside by arithmetic alone.