One of the three remote Chicago Basin fourteeners, reached only by train and a multi-day backpack — Windom is the most straightforward of the three standard routes.
Access is via the Durango & Silverton Narrow Gauge Railroad, which stops on request at Needleton (a backpacker fare and advance ticket are required; contact the railroad directly for schedules and reservations). From Needleton, the Needle Creek Trail climbs roughly 6 miles and 2,800–2,900 feet into Chicago Basin, where most parties establish a multi-day camp — no wood fires are permitted anywhere in the Needle Creek drainage or Twin Lakes basin. From a Chicago Basin camp (around 11,100–11,200 feet), the West Ridge route to Windom climbs roughly 3 miles and 3,000 feet of Class 2 terrain to the summit at 14,082 feet, typically climbed alongside Sunlight Peak on the same outing given their shared approach.
Reverse the route back to camp, and eventually back down to Needleton to flag down the train for the return trip — standing on the correct (east) side of the tracks and signaling clearly, since the train will not stop otherwise.