This ride starts appropriately at the train station in Samedan and climbs up over the historic Bernina Pass (2253 m; 7392 ft) before crashing down to the train station in Poschiavo. The route generally parallels the tracks of the famed Bernina Express railway which was completed in 1910.
This is a great example of Swiss engineering conquering the rough terrain and the route features numerous stone bridges and tunnels. The Bernina Express is the steepest and highest railway in Europe, but it is less well-known than the Glacier Express that runs from Zermatt to St Moritz.
As you cross through the pass, you'll switch from the Romansch to the Italian speaking regions of Switzerland and from the Black Sea Basin to the Adriatic Sea Basin.
The scenery is stunning as the valley is surrounded by 3000 m (10000 ft) peaks including the 4093 m (13428 ft) Piz Bernina, the highest point in the Eastern Alps from which the Bernina Glacier extends. You'll also pass the glacial Lago Bianca (White Lake) at the pass.
Once you've "finished" the ride in Poschiavo, you take the train back to Samedan. Get off at the Ospizio Bernina station at the pass and race the train back to Samedan. Alternatively, ride down the main road (Highway 29) from Poschiavo into Tirano, Italy. With this option, you'll pass by the famous spiral viaduct in Brusio, Switzerland. You can catch a train from Tirano, Italy back to Samedan, but see the important information below.
This trail is signed as the 673 Bernina Express MTB route, however, see the detailed description about the last several miles and different options.
There are long and sustained downhills on this ride. Make sure your brakes are in good working order before you start, and consider carrying an extra set of brake pads if yours might be near the end of their life.
The Swiss train system is excellent. Generally, there will be a special car for bikes - look for the silhouette of a bike on the outside of the car. You'll need to buy either a daily velo pass or the equivalent half fare ticket to cover the bike, in addition of course to your own ticket. Do not ride the Swiss trains without valid tickets - there are conductors on most trains and fines are steep.
The special panoramic Bernina Express cars do not allow bikes. However, there are regional trains that follow the same route from Samedan to Tirano and back and these allow bikes.
Follow the yellow brick road. The yellow and red waymarking signs are generally excellent so you don't need turn-by-turn directions (but you have probably wisely downloaded the GPX from MTB Project and the MTB Project mobile app
The first 15 miles climb to the pass up the Bernina Valley. I suppose you could take the train from Samedan to the top of the valley and then ride down but that wouldn't be much fun and that's now how the Swiss designed the route. You'll pass through some pasture lands, so watch for cows, calves, and their byproducts. You may have to open and close electric fences along the way. The first 7.5 miles follow the Samedan - Morteratsch Bike Trail
, a gentle climb to Morteratsch station.
When you reach Morteratsch station, cross the train tracks and the river and prepare for a short (0.5 mi) climb of about 20% grade. In this short, steep climb you'll pass under a stone bridge for the railway through which a waterfall tumbles. At the end of this climb, you'll exit a forest, coming to a row of very large stones neatly placed across the valley at around nine miles. Presumably the Swiss placed them here to keep out invading armies. The second section of the climb is mostly singletrack and also at a more reasonable grade, generally less than 5%.
After you reach the Bernina Diavolezza station, you can look forward to about three miles of relatively flat riding through the pass, also mostly on singletrack. When I did this ride in late June, there were still patches of snow, so if you do it earlier you may need really fat tires.
You pass Lago Bianca (White Lake) which is dammed on both the north and south. To the north, the lake drains to the Black Sea via the Danube River and to the south it drains to the Adriatic Sea via the Po River. The Ospizio Bernina station is at the center of the lake and this provides a good reference point if you are planning to get off at this stop for the downhill into Samedan on the reverse trip.
Around mile 17, you begin the first, long 400 m steep downhill (1400 ft in 2 mi). Hopefully, you checked your brakes before the ride! Near the top, you'll pass two mountain huts (Belvedere and in the Alp Grüm station) where you can stop for a good meal with your favorite beverage. From either, you've got excellent views to the north of the 3900 m (12795 ft) Piz Palü with its glacier and lake. To the south, you'll have views of the val Poschiavo (Poschiavo Valley) and a preview of the Alp Grüm Descent
From Cavaglia station, you'll have a "relatively" flat (with several 100-200 ft climbs) section for about five miles. This section follows mostly forest roads and two short connector trails until you reach a small farm at the upper end of the Val d'Urse.
At this point, the waymarking signs failed me, but the only viable option is a fun and challenging val d'Urse
singletrack down the valley paralleling the creek. Watch for farm animals and electric fence openings here. After about one mile, you'll reach a forest road which you can follow down into Poschiavo. Alternatively, if you don't want to do the challenging singletrack or wish to avoid the several 100-200 ft climbs, you can take one of the forest roads down to Poschiavo that intersect with the route at about 22, 22.5, and 23.3 miles.
From Poschiavo station, the official route is to take the train back up to the Ospizio Bernina station and then ride the 800 m (2620 ft) downhill back into Samedan. There is nothing to stop you from simply riding back up to Ospizio Bernina except you have several sustained 20% climbs to contend with.
Alternatively, you can ride the main highway south to Tirano, Italy to the terminus of the Bernina Express. In Tirano, there is a relatively flat 80 km (50 mi) bike trail that follows the Valtellina Valley (Adda River) to Lake Como. Regardless of which route you choose, be sure to check the train schedules so that you can get back to wherever you need to end up.