Colle di Zambla by bike: the climbs from Ponte Nossa and from Ambria

You leave Val Seriana at Ponte Nossa and climb the SP46 via Erdeno, Oneta and the Cantoni d'Oneta. The salite.ch profile shows a climb in steps: the first 2 kilometres are almost flat, then up to kilometre 4.5 the gradient stays between 7 and 8 per cent; two false flats follow, at 2 and 3 per cent, around Oneta, and from kilometre 9.5 a long ramp between 7.5 and 8 per cent broken only by half a kilometre at 6.

Maximum gradients depend on how they are measured: climbfinder finds 12.2 per cent over the steepest hundred metres, CyclingCols gives 10, myCols 8.5, and salite.ch never goes above 8 on sections of half a kilometre or more. Wikipedia describes it as winding and, in its last part, without shade. Valle Seriana Bike's Arera Tour avoids the first stretch of main road with the Val del Riso cycle path, which runs on its own track from Ponte Nossa to Riso, and then climbs the SP46 for the last 10 kilometres.

From the Brembana valley main road you turn off at Ambria di Zogno onto the SP27 and climb through the gorges of Val Serina, the hamlet of Galleria, Algua and Serina. According to salite.ch the first 5 kilometres stay between 2 and 3 per cent; from the sixth kilometre the road climbs steadily between 4 and 6.6 per cent to Serina, at 830 metres, and carries on like this to the hardest kilometre before Valpiana, at 7.3 per cent. The Percorsi MTB Val Brembana description calls this stretch steady and easy to ride.

From Valpiana to the twentieth kilometre the road hardly climbs at all: six kilometres of false flats and short descents, with Oltre il Colle halfway. The last three kilometres after Oltre il Colle climb again, at 7.4 and 6.1 per cent, before the final 3.1. Wikipedia counts 23 kilometres from Zogno with steep sections that do not exceed 11 per cent, the same maximum as CyclingCols; climbfinder finds 9.6 per cent over the steepest hundred metres.

On 11 June 1976 stage 21 of the Giro, from Terme di Comano to Bergamo, 238 kilometres, crossed the Croce Domini, the Colle Gallo, Zambla and Selvino (BikeRaceInfo). Gianbattista Baronchelli was first over the Colle di Zambla (CyclingCols); on the descent the leader Johan De Muynck crashed, the bunch waited for him and then the racing started again (OA Sport). The stage was won in Bergamo by Felice Gimondi, who the next day, in the Arcore time trial, also won the Giro (OA Sport).

On 9 June 1977 stage 19, from Pinzolo to San Pellegrino Terme, 205 kilometres, crossed the Tonale, the Presolana and Zambla: Renato Laghi went over first and won alone after a long breakaway, 1 minute 32 seconds ahead of Baronchelli; it was his only professional win (CyclingCols, BikeRaceInfo, Wikipedia).

Il Lombardia came back to the area in its 2023 and 2025 editions, both from Como to Bergamo over 238 kilometres, with the sequence Roncola, Berbenno, Passo della Crocetta, Zambla Alta and Passo di Ganda (RCS Sport): in 2023 Tadej Pogačar won, attacking on the descent of the Ganda. The 10 October 2026 edition, from Bergamo to Como, does not pass through Zambla.

The Colle di Zambla is one of the key passages of BERGHEM#molamia, the sportive organised by SC Gazzanighese starting and finishing in Gazzaniga: in its seventh edition, on 14 June 2026, all three routes, of 73, 120 and 185 kilometres, included the feed station at the Passo di Zambla and a timed section from via Costa in Oltre il Colle up to the pass.

The Brembana side depends on the SP27, which this year was closed for more than a month: from 28 August 2026, after a large boulder fell at Rosolo di Algua, with traffic and line B buses diverted via Costa Serina, until it reopened on the afternoon of 1 October 2026 (Valbrembanaweb, Arriva). Before setting off, check the Province's road news.

At the pass there are bars, restaurants and a fountain, useful before descending the other side (Wikipedia, L'Eco di Bergamo). The fountains along Val Serina are at Galleria, Serina and Valpiana (Percorsi MTB Val Brembana).