How Route Pacer works
Route Pacer reads two things — the course in front of you and the running you've already done — and turns them into a predicted finish time with split-by-split paces. Here's what's happening under the hood, in plain runner terms.
Why raw pace lies on hills
Your watch says 10:30 per mile and it feels like a tempo run. That's what hills do: raw pace tells you how fast the ground went by, not how hard you were working. A mile up a steady climb and a mile on a flat road at the same pace are completely different efforts — so judging a hilly race by flat-pace math sets you up for splits you can't hold.
Grade-adjusted pace (GAP) fixes the comparison. It asks: if this stretch had been flat, what pace would the same effort have produced? Route Pacer computes that using the Minetti energy-cost model — laboratory measurements of how much energy running costs at every gradient from steep descents to steep climbs. Under that model, a roughly 11:00 mile up a steady 6% grade costs about the same energy as an 8:00 mile on flat ground.
One nuance runners often find surprising: downhills help, but less than you'd hope. On steep descents, braking forces take over — your quads are doing real work just to control the drop — so the model deliberately caps how much credit steep downhills get rather than predicting free speed that isn't there.
Want the citations? The full methodology, with the published research behind every model, lives on the science page.
The four colours you'll see everywhere
Every segment of your race is classified into one of four effort zones based on its energy cost relative to flat ground. The same colours run through the elevation chart, the splits table, and the downloadable plan, so once you know them you can read a course at a glance.
Downhills and flats up to ~1% grade
Terrain that costs no more energy than flat ground. Descents land here too — metabolically they're the cheapest running there is.
~1–3.5% climbs
Gentle, sustained rises. You feel them, and the model expects your pace to ease accordingly even though the effort stays steady.
~3.5–6.5% climbs
Proper hills. Energy cost climbs sharply here — the model predicts a markedly slower pace for the same effort.
Steeper than ~6.5%
Power-hiking territory for most runners. The model knows paces here look nothing like the rest of your race.
From your recent runs to a personal pace profile
A generic pace calculator assumes every runner handles hills the same way. You don't — nobody does. Route Pacer builds the prediction from how you actually run, using your recent Strava history. (No Strava? You can also start from a goal time or goal pace instead.)
Sync recent runs
Connect Strava and Route Pacer looks at your recent training runs — three is enough to get started, more sharpens the picture.
Analyse grade vs. pace
Each run is analysed point by point: at every moment, what grade were you on and what pace did you hold? That converts every hilly mile into its flat-equivalent GAP.
Build your pace profile
Those flat-equivalent paces are combined into a personal pace profile, weighted toward your most recent weeks — so the prediction reflects your fitness now, not last season's.
Apply it to your course
The profile is run over every segment of your race course, with adjustments for surface type, heat and humidity, altitude, and a fatigue correction when the race is much longer than your training runs. The result: a finish time and the splits behind it.
Honesty is part of the model. If your race has terrain steeper than anything in your training, or it's far longer than your longest recent run, the prediction is shown with an uncertainty range and a plain-language warning rather than a falsely confident single number. And your raw GPS data isn't kept — runs are analysed and the coordinates discarded.
What you'll see on your plan
Every prediction lands on a plan page built to be read twice: once at your desk, once nervously the night before the race.
Predicted finish time
The headline number, with a range when confidence is moderate or low. Underneath, a one-line breakdown shows how the time was built: your flat baseline, then what grade, surface, weather, altitude, and distance fatigue each added or took away.
Elevation profile & predicted pace
The course profile with the predicted pace drawn over it, coloured by effort zone — you can see exactly where the course will be slow before you get there.
Splits, three ways
A per-mile (or per-km) table is the default. A toggle switches to terrain-based splits — the course narrated as climbs, descents, and flats — or to terrain sections, contiguous climb/descent/flat stretches each with its own predicted pace. Rows are colour-coded by zone, and hovering a row highlights that stretch on the chart.
Surface mix
How much of the route is paved, gravel, or trail, with a pace allowance applied where the footing is rough or technical.
Adjust & recalculate
Enter a goal finish time or a goal flat-equivalent pace and the splits redistribute across the course instantly — useful for seeing what a particular goal implies on this specific terrain. A km / mi toggle switches every number on the page.
Exportable split card
Download your plan as a PDF split card — print it, share it, or keep a screenshot on your phone for race morning.
Course map (library races)
Races from our course library include an interactive route map with the effort zones drawn along the route. Courses you upload yourself are processed without storing any location data — by design — so they skip the map.
What this is — and isn't
Route Pacer is a prediction tool: it computes what your training history suggests is achievable on a specific course under specific conditions. It's not a coach, and it isn't medical or training advice — race day always involves judgment calls that no model can make for you. We'd rather show you an honest range with a warning than a precise-looking number the model can't actually back up.