How accurate are 2k erg predictions from longer tests?

For most New Zealand club rowers, predictions from 5k and 6k tests land within 4-8 seconds. Extending to a 10k or 30-minute test increases the typical range to 6-12 seconds because the aerobic-anaerobic split diverges further from the 2k profile. Heavier rowers tend to come in ahead of the prediction on 2k day because body mass supports sustained aerobic output; lighter rowers can fall short for the same reason. Running all three confidence bands and matching the one closest to your historical pattern between distances is the most practical approach for any NZ squad preparing for ergo trials.

Why does the calculator give three different times?

Physiological makeup sits on a spectrum. The best-case estimate uses a Riegel exponent of 1.05, characteristic of rowers who close hard and hold pace well between a 6k and a 2k. The likely estimate uses 1.06, the population average across endurance sports. The cautious estimate uses 1.07, typical for rowers carrying accumulated fatigue from heavy training or those with a more purely aerobic profile. Think about how you normally bridge from a 6k pace to a Maadi or NZ Champs 2k standard: if you fade through the third 500m on hard pieces, lean toward cautious. If you consistently negative-split, lean toward best.

What is a sensible 2k pacing strategy?

An even split or slight negative split covers the majority of successful 2k performances. An even split targets the same 500m pace at each marker. A negative split opens 1-2 seconds slower and closes the last 500m 1-2 seconds faster. Going out 5 or more seconds under target, the fly-and-die, almost always costs more time between the 1000m and 1500m marks than it gained off the start. At Lake Karapiro or Lake Ruataniwha, that collapse is visible from every club tent on the bank. The calculator gives you explicit 500m targets for each predicted time so you can choose your approach before you sit down.

Should I use a 5k, 6k, 10k or 30min test for prediction?

The 5k shares the most metabolic overlap with the 2k and is statistically the sharpest predictor. The 6k is a common test distance across NZ university programmes and Rowing NZ development squads, making it the most available data point for many New Zealand rowers. The 10k and 30-minute results sit deeper in aerobic territory and need careful interpretation - they tend to slightly overpredict 2k performance in rowers who have not done dedicated speed work. If you have results at several distances, run the calculator on each and use the average. Squads that test across 2k, 5k and 6k consistently through the season develop a personal Riegel exponent for each athlete, which is what experienced coaches mean when they say they know how a crew performs under pressure.

2k Erg Prediction Calculator for NZ Rowers: Predict 2k from 5k, 6k or 30min

Race-day pacing

2k Prediction Calculator

Enter a 5k, 6k, 10k or 30-minute erg result and get three confidence-banded 2k estimates with the 500m-split race plan to hit each one. Built on the Riegel endurance formula with three exponent presets to match your physiology.

How do you predict a 2k erg score?

The Riegel endurance model is the standard method: T2 = T1 multiplied by (D2 divided by D1) raised to the fatigue exponent. For most New Zealand club rowers and university athletes that exponent sits at 1.06. Feed in a 5k, 6k or 30-minute result and the formula returns your expected 2k. Rowers in peak race condition ahead of the Maadi Regatta or NZ Rowing Championships lean toward 1.04; athletes deep in a winter base block sit closer to 1.08.

Your test result

Test type

Time

: min : sec

Distance covered (metres)

Typical 30-minute distances: 7,000m (recreational), 8,000m (club), 8,800m (university), 9,500m+ (national).

Test summary

Predicted 2k (likely)

Best case

Cautious

500m race plan for each prediction

Even-split target (recommended for most rowers). Negative-split alternative below.

Prediction	Target time	500m	1000m	1500m	2000m

All four 500m segments at the same average split. In practice the opening 500m runs 2-3 seconds fast off the start; the closing 500m runs 2-3 seconds fast in the sprint. The two middle segments are where your prediction holds or breaks.

Negative-split alternative

Open 1.5 seconds slower than your target average and close 1.5 seconds faster. For your "likely" prediction of , that means:

Negative splits suit rowers who close strongly on hard pieces. If your third 500m is historically your worst segment, an even split is the more reliable choice.

How the prediction works

The Riegel formula with three exponents

Pete Riegel's endurance formula T2 = T1 * (D2 / D1)^c converts a known time at one distance into a predicted time at another. The exponent c captures how quickly a given athlete fades as distance increases. Across endurance sports the population average is 1.06, but individuals range from about 1.04 (strong anaerobic closing speed) to around 1.08 (predominantly aerobic). The calculator runs all three - 1.05 (best case), 1.06 (likely) and 1.07 (cautious) - and shows the resulting 2k for each.

Why predictions are not perfect

The Riegel model assumes the same physiology governs performance at both distances. A 2k is roughly 75-80% aerobic and 20-25% anaerobic. A 5k is around 90% aerobic. A 10k sits at about 95%. As the distance between test and target widens, the model extrapolates more heavily into anaerobic territory that the test itself did not evaluate. That is why a 30-minute prediction carries a wider margin than a 5k prediction for the same rower.

Pacing strategy decoded

An even split is the safest plan for most rowers: every 500m segment hits the same target. Negative splitting - opening conservatively and closing hard - works if you have a genuine anaerobic kick and the pacing discipline to hold back early. Going out hard and hanging on, the fly-and-die, nearly always costs more time in the 1000m-1500m segment than it gained off the start. Lactate accumulation at that point outpaces clearance, and the result is visible from the clubhouse at Karapiro. The calculator gives you splits for each approach at each predicted time.

Use this with the training pace calculator

Once you have a predicted 2k, plug it into the training pace calculator to get your UT2, UT1, AT, TR and AN target splits. Use the rowing pace chart to see where the prediction sits across every distance. Use the erg score calculator to convert it into a weight-adjusted, age-graded percentile that holds up across crew selection at different weight categories.

Predicting your 2k is one calculation. Selecting a crew from squad predictions is twenty.

A coach at West End Rowing Club or Waikato Rowing Club building a Maadi squad wants 2k predictions for every crew member from their last 5k and 6k tests, weighted by recency, grouped by confidence band. That is what Row HQ does inside coach tools, pulling lineups from live data through training session tracking. See it in action or read the crew selection guide.

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