EuskalTrail 130 km: How I Built My Race Strategy with Segly

5 days to go. My favourite moment before an ultra. The legs are fresh, my head is full of scenarios, and the excitement starts to build. This week, I barely run at all — I prepare. And that preparation goes through Segly.

Today I'm taking you step by step through the construction of my strategy for the EuskalTrail 130 km / 7,900 m D+ on 15 May. It's all there: the target, the segments, the terrain adjustments, nutrition, the plan B. Fasten your seatbelts.

1. The context: 130 km, 7,900 m D+, and rain

The EuskalTrail is serious. 130 km, 7,900 m of positive elevation in the Basque Country — technical terrain, committed passes, descents that eat up the quadriceps.

And this year, the weather isn't going to help. At D-5, the forecast calls for rain and around 10°C. That means humidity, slippery trails, thermal discomfort over the long haul. Nothing insurmountable, but it has to be anticipated.

2. The target: 21 hours, with a plan B at 23 hours

I set myself a main target of 21 hours. It's ambitious but realistic if everything goes to plan. And because an ultra is also about handling the unexpected, I'm building a plan B at 23 hours in parallel. A minor injury, a passing dip, capricious weather — better to have a spare wheel in your pocket.

3. Opening Segly: automatic split no. 2

I import the EuskalTrail GPX file into Segly and choose automatic split mode no. 2: the one that adjusts segment length according to gradient. The result: short segments in technical or very steep zones, longer ones on rolling sections. Far more relevant than a uniform kilometre split.

I rename the project EuskalTrail 130 — 21h and save it. It sounds basic, but finding your strategy again on D-1 without having to redo everything is priceless.

4. The fatigue factor: why I start at 15%

I set the fatigue factor to 15%. That means I plan to run the second half of the race 15% slower than the first. It's not pessimism — it's clear-headedness.

On an ultra, wanting to run at constant intensity from start to finish is an illusion. And if you still doubt it, look at the analyses I did of the UTMB 2022–2025 winners (see the article on the UTMB fatigue factor): their fatigue factors all hover around 10 to 15%. Starting too cautiously often means losing time where you're still fresh. The key is to accept a positive split and control it.

5. Visualisation: map + profile, everything lights up

We run the analysis. Immediately, the map and the elevation profile light up: each segment has its colour, its progression factor, its estimated time. At a glance, I can see the profile, where it's going to hurt, and how the effort is spread over 130 km.

This is where preparation becomes truly concrete.

I also look at the overall statistics, which can be daunting when taken as a whole but far more manageable when broken into pieces. I also lock the total duration so that future adjustments don't change it.

6. Terrain adjustments: because the GPX doesn't tell everything

An algorithm doesn't know the trails. I do. Thanks to my reconnaissance, I refine segment by segment:

• Km 0–10: very rolling, easy route. I slightly raise the progression factor.
• Km 23–35 (Iparla area): very technical, scree slopes, committed ridges. I lower the factor — no question of burning out here.
• Km 100–120: will be run at night, moderately technical terrain with reduced visibility. I lower the factor a little to stay cautious.
• Weather: no major heat forecast, so no need to reduce the factor between 11 a.m. and 6 p.m. as I would on a summer race.

Each adjustment is immediately reflected in the split times. It's iterative, and it's powerful.

7. Segment comments: the built-in logbook

This is the step I love. I go through each segment and add personalised comments. It becomes a real logbook:

• Geographical landmarks: names of passes, villages, key passages — to orient myself during the race even when my brain is tired
• Crew points and aid stations: which ones not to miss, what I need to pick up there
• Nutrition strategy: on which segment to fill up, how many gels / bars / drink, what I'll leave with the crew
• Clothing strategy: changing socks, shoes, adding a layer — everything planned in advance
• Poles: I note whether the segment is run with poles in hand (climbs) or stowed (technical descents, flat and rolling sections)

By the finish, each segment tells a story. It's no longer just a time — it's a complete race plan.

8. Re-splitting: the aid stations must fall in the right place

We check that the important passage points coincide with segment ends. That isn't always the case with automatic splitting.

For example, I split segment 6 in two:

• Segment 6: from the summit of Iparla (km 23) to the Col d'Ispegui (km 32)
• Segment 7: from the Col d'Ispegui to the summit of Autza (km 36)

Result: I now have a precise split time at the Col d'Ispegui, where my crew is waiting for me. Nothing is left to chance.

9. Export and sharing: everyone in the loop

The strategy is finalised. Last review, then export:

• Full PDF: all segments, all comments, the whole strategy — for my crew
• Condensed PDF: the essential split times — possibly printed and put in my pocket

I then generate the read-only share link and send it to my crew. They can access my whole strategy from their phone, with no account and no hassle.

10. The plan B: duplicate in 30 seconds

I duplicate the analysis, rename it EuskalTrail 130 — 23h, and all the times recalculate automatically. I also share this link with my crew.

If plan A goes off track, everyone knows what to do. No panic, no improvisation.

11. Strategy complete. We're ready.

The strategy is in place. My crew has everything in front of them; we'll talk it through together before the start so they know every detail.

On my side, I know exactly what's waiting for me segment by segment. The split times, the aid stations, the nutrition, the clothing, the hard moments I've anticipated.

All that's left is to run.