The Big Lost is the new name for Rebecca's Private Idaho, the gravel weekend that has run every September in Sun Valley and Ketchum, Idaho since 2013. The 2027 edition runs September 8-11 and keeps the multi-day format: a 35-mile Harriman stage of single and double track below the Boulder Mountains on Wednesday, a 50-mile Dollarhide day with a timed 4.5-mile hill climb on Thursday, an expo and shakeout ride on Friday, and the main event on Saturday with four routes: the 19-mile Tater Tot, 57-mile French Fry, 104-mile Baked Potato over Corral Creek Summit and Trail Creek Summit, and the 118-mile Fully Loaded, which adds the Copper Basin loop.
Organizers Bike Monkey announced the rename in August 2026, after the 14th edition, as Rebecca Rusch steps back from the event; the new name comes from the Big Lost River that riders follow through Copper Basin and Wildhorse. The ride has been named a top-five gravel event by Global Cycling Network and one of Outside's 25 best bike rides in the world. Riders can enter single stages or the full three-stage race, with group, veteran and junior discounts. Registration for 2027 had not opened as of late October 2026.
Race-day forecast is not available yet. Forecast data appears within 14 days of the event, so this section is showing historical race-day averages for planning.
77°
Overcast
Low 47° · High 77°
5 years analyzed
1 of 5 years had precip
Based on race-day weather from 2021-2025 sampled years.