Concept2 Ergo Monitor

Connect your Concept2 rowing machine via USB to see live metrics, force curves, and stroke-by-stroke analysis — all in the browser, no install required.

Connect your erg. Plug the USB-B cable from your Concept2 PM3/PM4/PM5 into your computer. Turn the monitor on.

Click Connect. Your browser will ask you to select the Concept2 device from a list. Pick it and click Connect.

Start rowing. Switch to the Live tab to see metrics and force curves update stroke by stroke.

Opens a browser device picker. The erg must be connected before clicking.

Chrome / Edge only, served over http://
WebHID requires Chrome or Edge. It also requires the page to be served over http:// — opening directly from a file will block output reports.

Quick local server (Terminal/CMD): python3 -m http.server 8080 Then open: http://localhost:8080/ergomonitor.html

No erg available right now? Load demo data to explore the interface with a sample session.

Session

00:00

Pace

–:––

per 500m

Power

0

watts

Stroke Rate

0

strokes/min

Distance

0

metres

Calories

0

kcal

Heart Rate

–

bpm

Drag Factor

–

×10⁻⁶

Stroke Phase

Waiting

Stroke log

Strokes will appear here

Force curves require imported CSV data. Live rowing provides Power & Pace History.

Per-stroke inspector Click any stroke to examine it in detail Stroke 1

STROKE SELECTOR — click to inspect

Force Curve

Biomechanics

Peak Force vs % Drive Position

Scatter of all strokes — ideal: high force, early position (top-left)

Impulse vs Drive Time

Each dot = one stroke — larger impulse in shorter time = more powerful

Rowing blocks Automatically detected from gaps >5 s in the session

Block Comparison

Mean Force Curve by Block

Peak Force Across Session

Each bar = one stroke, coloured by block — shows fatigue and between-block recovery

Stroke trim Remove first Remove last

Phase markers Click the timeline to add/remove phase splits — colours update across all tabs

Average Force Curve

Row some strokes or import a CSV to see your force curve

Session Statistics

Total strokes0

Avg power– W

Peak power– W

Avg pace–

Avg stroke rate– s/m

Peak force @ % drive–

Avg drive time–

Drive time CoV–

Avg recovery time–

Drive:Recovery ratio–

Avg work / stroke– J

Avg catch slip–

Curve CoV (consistency)–

Kleshnev shape parameters

A70 catch gradient–

A100 peak position–

D70 finish gradient–

Negative work–

→ Full Benchmarks Report Card

Technique Classification

Load strokes with force data to see technique classification.

Split markers Click on the stroke timeline to add/remove split points % change vs

STROKE TIMELINE — click to place splits

Add strokes and place split markers to compare segments.

Time periods Split by stroke count, active time, or detected rowing blocks

Split by

Row at least 6 strokes to see time period analysis.

Period Comparison

–

Force Curve by Period

Mean force curve for each time period — darker = later in session

Session A

Current session — loaded automatically

No data loaded

Label (optional)

Session B

Load a second CSV to compare against Session A

No file loaded

Label (optional)

⚖

Load a Session B CSV above to begin comparison.

Session A is the current session. Tip: trim startup strokes with the trim controls on Force Curve first.

PM4 Session Data

Drag factor–

Workout type–

Workout state–

Calories–

Computed Session Summary

Strokes logged–

Rowing blocks–

Session span–

Active rowing time–

Mean power–

Peak power–

Mean pace–

Mean stroke rate–

Mean drive time–

Mean recovery time–

Mean peak force–

Peak force (max)–

Total work (est.)–

Power & Pace Over Session

⚡

No strokes logged yet

Kleshnev Force Curve Report Card

Three shape parameters from Kleshnev's biomechanics framework — each compared against published target ranges for competitive rowing. Based on your mean force curve across the current session.

A70 — Catch Gradient

–

Drive angle to reach 70% of peak force (Fmax). Target: ≤17% of drive at training pace (Table 9.2, sculling/rowing mean). Requires leg and trunk activation — small muscles alone cannot reach 70%.

0%Target ≤17%35%+

A100 — Peak Force Position

–

Where in the drive peak force (Fmax) occurs. Front-loaded styles with leg emphasis produce an earlier peak. Target: ≤40% of drive. Late peaks (>55%) indicate trunk/back dominance or poor sequencing.

0%Target ≤40%100%

D70 — Finish Gradient

–

Width of force plateau above 70% of Fmax after the peak. Target: 28–40% of drive (sculling mean 35.6°T/38.2°R; rowing mean 30.3°T/34.0°R — Table 9.2). Wider = effective use of arm and trunk finish.

0%Target 28–40%60%+

Curve Quality Flags

Per-session averages. Flags indicate technique issues visible in the force curve shape.

Negative work (wasted effort)–

Drive curve humps / glitches–

A70 catch gradient–

Drive:Recovery ratio–

Drag factor–

Work per stroke (est.)–

Per-Stroke Quality Flags

✕ NEG negative work ~ HUMP curve glitch ⚡ LATE late peak

Annotated Mean Force Curve — Kleshnev Targets

Vertical lines show your catch gradient (blue), peak position (green), and finish gradient (orange) against the drive phase. Shaded zones indicate the Kleshnev target windows.

Kleshnev Force Curve Parameters — Reference Table

Normative values from Table 9.2 in: Kleshnev, V. (2011). Biomechanics of rowing. In V. Nolte (Ed.), Rowing Faster (2nd ed., pp. 105–121). Human Kinetics. Values expressed as % of total drive angle. T = training rates (<30 spm); R = racing rates (>30 spm). 🔍 Google Scholar ↗

Parameter	Sculling (T / R)	Rowing (T / R)	Your session	What it means
A30 — blade grip	5.8° / 3.8° ± ~2°	6.7° / 5.2° ± ~2°	–	Drive angle to reach 30% of Fmax. Tests blade entry quality and initial handle control. Correlates with blade propulsive efficiency (r = −.34).
A70 — catch gradient	17.2° / 13.4° ± ~5°	16.7° / 13.6° ± ~3°	–	Drive angle to reach 70% of Fmax. Requires leg and trunk involvement — small muscles alone cannot achieve 70%. Correlates with maximal leg velocity (r = −.28).
A100 — peak position	front-loaded <40%	front-loaded <40%	–	Position of Fmax in the drive. Leg-emphasis styles produce an earlier peak. Earlier peak improves initial boat acceleration and temporal effectiveness of the drive.
D70 — finish gradient	35.6° / 38.2° ± ~7°	30.3° / 34.0° ± ~8°	–	Width of sustained plateau above 70% of Fmax after the peak. Correlates with maximal leg velocity (r = −.38). Wider = effective arm-and-trunk finish through the handle.
Ra-m — rectangle index	50.9% ± 4.5%	50.9% ± 4.5%	–	Ratio of average to maximal force (Faver / Fmax × 100%). Range across rowers: 38–64%. Higher = more rectangular, more even distribution of effort. Correlates with blade efficiency (r = .32).
Drive:Recovery ratio	~1:2 (0.50)	~1:2 (0.50)	–	Drive takes ~1/3, recovery ~2/3 of the stroke cycle. Rushing the recovery increases fatigue and reduces hull balance.
Negative work fraction	<2% of impulse	<2% of impulse	–	Area of force curve below zero as % of total impulse. Indicates antagonist muscle activation or jerky movement — both waste energy. Kleshnev p.119: "negative power is the most inefficient."

Technique Signature

Drive:Recovery ratio, force ratio (f_p,r), and peak position benchmarked against elite ergometer rowing norms. Reference: Černe et al. (2013) Human Movement Science, 32(4), 691–707.

📊

Import a CSV session to see technique signature analysis.

Drive:Recovery Ratio vs Stroke Rate

Elite rowers' D:R ratio falls predictably as stroke rate rises — the shaded band shows the elite norm corridor (Černe et al. 2013: 1:2.04 @ 20 s/m → 1:1.31 @ 34 s/m). A flat ratio across stroke rates is characteristic of novice rowers.

How to read: Each dot = one stroke. The shaded corridor shows the expected D:R ratio range for elite rowers at that stroke rate. Dots within the band → elite-like timing. Dots below → too little recovery. Dots clustered horizontally (no slope) → novice pattern.

Force Ratio (f_p,r) — Avg/Peak

Elite rowers maintain f_p,r of 0.43–0.45 consistently across all stroke rates (Černe et al. 2013, Tables 1–3). High values indicate a broad, sustained drive; low values a sharp spike with poor force application.

Peak Force Position

Elite peak knee torque occurs at ~89% of handle position during the drive (Černe et al. 2013, Fig. 5). For handle force, the front-loaded target is ≤40% of drive (Kleshnev 2011). Both reference lines are shown.

Stroke-to-Stroke Consistency

Variance-to-Mean Ratio (VMR) of key parameters. Černe et al. (2013) classify VMR <0.05 as insignificant (consistent). Elite rowers show VMR ~0.03 for drive time and peak force; non-rowers average VMR ~0.14 for work.

Reference: Černe, T., Kamnik, R., Vesnicer, B., Gros, J. Ž., & Munih, M. (2013). Differences between elite, junior and non-rowers in kinematic and kinetic parameters during ergometer rowing. Human Movement Science, 32(4), 691–707. https://doi.org/10.1016/j.humov.2012.11.006 · 🔍 Google Scholar ↗

Stroke Log

No strokes logged yet. Connect and start rowing, or import a session CSV.

Import Session Data

Reload a previous session — with its force curves — without a live erg. Use the JSON — full backup file from the Export menu (top-right ↗). That is the only export that re-imports completely.

📊 Sample session ↓ CSV Real Concept2 session · 23 strokes · 3 rowing blocks

Drop your `ergo-session.json` backup here

or click to browse — JSON backup, or a CSV with a force-curve column

File loaded successfully.

Which export re-imports? The Export menu offers several files for different uses — only some carry the raw force curves needed to rebuild a session:

✓ JSON — full backup — re-imports completely (force curves, blocks, phases). Use this to reload.
✓ CSV with forceMap — legacy/Ergo Monitor CSV where each row is a stroke and one column holds the force curve.
✓ CSV — strokes + force curves — one row per stroke incl. the force curve; re-imports. (JSON keeps full timing fidelity, so prefer it for reload.)
✗ CSV — raw force curves / XLSX — analysis-friendly layouts, not built to reload here.

Concept2 Ergo Monitor

Session

Force Curve

Biomechanics

Peak Force vs % Drive Position

Impulse vs Drive Time

Block Comparison

Mean Force Curve by Block

Peak Force Across Session

Average Force Curve

Session Statistics

Technique Classification

Period Comparison

Force Curve by Period

Session A

Session B

Session Summary Comparison

Mean Force Curve — A vs B

Peak Force Distribution

Drive Time Distribution

Stroke-by-Stroke: Peak Force Trend

Biomechanical Metrics

PM4 Session Data

Computed Session Summary

Power & Pace Over Session

Kleshnev Force Curve Report Card

Curve Quality Flags

Per-Stroke Quality Flags

Annotated Mean Force Curve — Kleshnev Targets

Kleshnev Force Curve Parameters — Reference Table

Technique Signature

Drive:Recovery Ratio vs Stroke Rate

Force Ratio (f_p,r) — Avg/Peak

Peak Force Position

Stroke-to-Stroke Consistency

Stroke Log

Import Session Data

Drop your `ergo-session.json` backup here

Concept2 Ergo Monitor

Session

Force Curve

Biomechanics

Peak Force vs % Drive Position

Impulse vs Drive Time

Block Comparison

Mean Force Curve by Block

Peak Force Across Session

Average Force Curve

Session Statistics

Technique Classification

Period Comparison

Force Curve by Period

Session A

Session B

Session Summary Comparison

Mean Force Curve — A vs B

Peak Force Distribution

Drive Time Distribution

Stroke-by-Stroke: Peak Force Trend

Biomechanical Metrics

PM4 Session Data

Computed Session Summary

Power & Pace Over Session

Kleshnev Force Curve Report Card

Curve Quality Flags

Per-Stroke Quality Flags

Annotated Mean Force Curve — Kleshnev Targets

Kleshnev Force Curve Parameters — Reference Table

Technique Signature

Drive:Recovery Ratio vs Stroke Rate

Force Ratio (fp,r) — Avg/Peak

Peak Force Position

Stroke-to-Stroke Consistency

Stroke Log

Import Session Data

Drop your ergo-session.json backup here

Force Ratio (f_p,r) — Avg/Peak

Drop your `ergo-session.json` backup here