Gran Fondo Larra-Larrau: Course, Elevation & Route Profile

Course & Elevation

The start is at nine in Isaba at 764 metres, in the Roncal valley at the edge of the Navarrese Pyrenees. The first climb begins at kilometre 12 and runs 8.2 kilometres at an average of 7.1 per cent up to the Piedra de San Martín at 1,765 metres – the border pass beyond which the route drops into France.

The French section is the heart of the day. Over the Guilhers plateau the course rolls down to Arette before the longest climb starts at kilometre 61: 13.8 kilometres at 7.7 per cent and over a thousand metres of gain to the Col d'Issarbe at 1,450 metres. Then comes the long traverse through the Sainte-Engrâce gorge to the village of Larrau at kilometre 106, where the last big ascent waits: 4.4 kilometres at 10.7 per cent to the Puerto de Larrau at 1,573 metres. From there the Orhi tunnel leads back into Spain and the Paso Laza and Uztárroz bring you home to Isaba.

The Larra-Larrau is explicitly not a race: no time is taken from start to finish. Anyone wanting to measure themselves can opt into two timed climbs, on the Piedra de San Martín and on Larrau. The field is capped at 1,200 riders, with six feed stations, a broom wagon and the Larra Bus, which will carry riders and bikes from Larrau village up to the pass if needed. 2026 is the 31st edition.

Pacing Strategy

This course punishes a hard opening third more than most granfondos, because its biggest climb sits in the middle and its steepest right at the end. Ride the Piedra de San Martín at kilometre 12 – timed section notwithstanding – well below what you could do there: at 7.1 per cent over 8.2 kilometres it is the friendliest of the three big ascents and still long enough to ruin a whole day.

The 146K is decided on the Col d'Issarbe from kilometre 61. Thirteen point eight kilometres in one go at 7.7 per cent, after three or four hours already in the saddle, is the central demand of this course; it separates the riders who rationed the first sixty kilometres from everyone else. Ride to power, eat at the Arette feed beforehand, and expect over an hour of unbroken climbing.

The trap sits at kilometre 109. The climb to Larrau is the steepest of the day at 4.4 kilometres and 10.7 per cent, and it arrives after more than 100 kilometres and two big passes. Deliberately hold something back for it – and plan around the Larrau village feed, the last before the ramp. Early September is mild in the valley, but at 1,500 to 1,800 metres the passes can be considerably cooler and windier: carry a wind vest for the long descents.

Training plan for Gran Fondo Larra-Larrau: 12-week build

Expect 6 to 9 hours as an age-group rider. The demand is a long aerobic day built on three very different climbs: a medium-length opener, an exceptionally long one in the middle and a short steep one at the end. Just under 30 per cent of the course rises, more than a third falls, and only twelve per cent is genuinely flat.

The most important training content is the long steady climb. Ride ascents of 45 to 75 minutes in the upper endurance-to-sweetspot range regularly – Issarbe asks for exactly that ability, and short hard hill intervals prepare you poorly for it. Add at least two six-hour rides with 2,500 to 3,500 metres of climbing in the build phase.

The second priority is climbing strength under pre-fatigue. The Larrau ascent at almost eleven per cent arrives after more than 100 kilometres – simulate it by placing short steep climbs at the END of long rides rather than the start. Check your gearing while you are at it: on double-digit gradients after five hours, a bigger sprocket is worth more than extra watts.

Fuelling and cold round out the preparation. With six feed stations over 146 kilometres you have to bridge stretches of more than twenty kilometres yourself – practise your eating and drinking rhythm over at least five hours. And train long descents: on this course every big pass is followed by twenty to thirty kilometres downhill, on which you will get cold if your clothing and pace are wrong.