I have been several times here, both in summer and winter. I spent a couple of weeks here at the end of July 1995, and would like to report here on the place in general, and in particular which kind of cycling you can do here.
Gsies is a transversal of Val Pusteria/Pustertal. It is a closed valley. There is a pass at the end of it, leading to Austrian Osttirol, but it's only for hikers. Therefore Gsies is a quiet place: you get there only if you want to get there. Until the early seventies, there was no paved road through the valley. Although the valley has seen some touristic development since, it is not intensely crowded by tourists as the twin Anterselva/Antoholz valley. Still there are several hotels of various categories, and every other house has flats to let.
In winter, it is a paradise for cross-country skiing. There is a very small lift for downhill skiers at the end of the main road, where my children learned to ski. However, for serious downhill skiing one should refer to other nearby areas, such as Kronplatz/Plan de Corones.
In summer, there are many walks, of various degrees of difficulty. Many of them double up as off-road bike trails.
Three of these Alms I'd recommend are Uwaldalm, Kaseralm and Stumpfalm. At these you can get food and drink. Try the Kaiserschmarrn, a delicious Alpine omelette with raisins and jam, and the Brettljause (speck, sausage and cheese with Bauernbrot). Don't expect too much in terms of variety: the minestrone is most likely straight from the tin. If you like beer, a Weizenbier is to be recommended.
The access roads to the Alms are good for mountain biking too. I tried the one to Uwaldalm on a very hot afternoon, and found it a bit steep at times. Some friends of mine went up to Stumpfalm and Kaseralm, and found it acceptable. You can then proceed to Uwaldalm, and get down that way. This involves some carrying on illegal trails.
If you're terribly good at downhill, you may try coming down on the Abkürzung (shortcut) from the Uwaldalm: refer to a map for details. Note that this is extremely steep, and the road-bed, altough mostly good, can be treacherous at times. Also, slow down before blind spots, to avoid running down hikers. I undertake no responsibility if you get seriously killed by trying this trail, nor if you injure bystanders.
A not too difficult ride takes you up the valley, toward the pass. This is at first paved, then gravel, and ends on an illegal trail.
The way I did it, I started from the end of the main Strada Provinciale/Landestrasse, near to the ski lift and a small restaurant. The official start is in Monguelfo/Welsberg, at the other end of the valley. A sign shows a possible diversion to Pidigalm, on the way to the pass.
One starts down on the main road, staying on the right of the river (looking downstream), going through St. Magdalena. Just before the church, one may take a brief diversion to the left, to visit an old mill. The building is falling to pieces, really, but let's hope that they restore it before it's too late.
Further down, at the blue St. Martin sign, one has to turn left onto a bridge, and then immediately right, over another bridge. On a narrow paved road one reaches St. Martin. Here after 50m on the main road one turns right, and then hits the dirt for the first time by turning left after a bridge. On reaching a group of houses (one of them nicely decorated), one turns left, and rides for a few hundred meters on the main road. On reaching Preindl/Prateria one turns right, then immediately left, and immediately after the Hotel, with the saw-mill in front, right (try and find the sign here: there is one, but difficult to spot). One stays on pavement, pointing to the Steinegg houses, at the margin of the wood. Here one joins the Talblickweg, a very comfortable hikers path, legal for bikes here.
This part is very nice, and runs through the woods. Immediately after a small stream crossing, one is faced with the main choice. To make the path really simple, one has to turn left onto an evident, although lightly marked, path through a meadow. One crosses the main road, reaches the first houses of Oberplanken, and turns right into the old road of the valley, that takes you comfortably to Monguelfo/Welsberg..
Instead, I stayed on the Talblickweg, aiming at a slightly more challenging option. At some point you have to leave the Talblickweg on the right and turn left instead, but that's clearly signposted. After a stream crossing that may well turn to be unmanageable if there's plenty of water, one reaches the pavement at Innerpichl, turns right, and starts ascending. On reaching Ausserpichl, at the church I avoided the wider road which would have lead downhill, to rejoin the old road of the valley, and took the narrower road on the right, which keeps ascending. At a fork, I took the right branch, guided by a wooden sign to Schindholz. From there it's all downhill to Taisten/Tesido, and then, on the steep main road (you may be tempted to enjoy the pleasure of speeding here), to Monguelfo/Welsberg. The town would be nice, but it's doomed by the Strada Statale going through it. After some days in Gsies, Welsberg looks like New York to me.
I didn't join the perennial queue, and stayed on the side-walk, soon to find the signs leading back to the Path and the Castle. I actually followed the signs to the Castle (which deserves a visit), managing the one steep but brief ascent of the day.
This part of the trail is now very nice, leading you up the valley with no visible gain. I couldn't resist a bit of hammering, taking care of slowing down when passing or meeting other bikers and hikers. At the first houses of Oberplanken, I turned left, and across the main road to rejoin the Talblickweg. Retracing my steps, after St. Martin I went back to the starting point staying on the left of the river. All in all it was about 40km.
If you're using public transportation, there's a railway line going through Val Pusteria/Pustertal, and some buses up Gsies.
The most important point is that they require you to ride only on trails that are at least 1.5m wide, so to allow transit to a vehicle.
This may appear as a severe restriction, banning the fun of singletrack riding. One should consider, however, that people from these places have been leaving among these mountains for centuries, and know a thing or two about erosion.
I visited a museum of local traditions, and saw an impressive depiction of the work that farmers used to do to fight erosion on the steeply slanted meadows up in the mountains. They used to bring back loads of earth from the bottom to the top of the meadows, carrying them on their shoulders in huge baskets. Today, I found a team of workers securing the terrain at 2300m, to prevent landslides. And every small village has a team of voluntary firemen, consisting of all able men (not terribly p.c., huh?), ready to fight in emergencies. Four years ago, during a previous visit to the valley, I heard a siren scream through the night. A stream was being blocked by debris, and a flood might have resulted, with damage to some farms. Everybody ran to help, and the problem was fixed.
Therefore my opinion is that these people know what they're doing, and if they think that one should not ride on singletracks, they probably have a good point. Please note that this is only a recommendation right now. However it is safe to comply, to avoid real trail closures. The network of forestry road is so extensive here, that there is enough for a lifetime of mountain biking.
The second book of the Margoni brothers has some rides in the area. Other books have more: look them up in one of the local bookstores. Some Tourist Offices have some small guides to local trails.
The Castle is now managed by a local association (Kuratorium Schloss Welsperg), that keeps it open from 1988, and uses it for exhibitions, concerts, and other cultural event. In 1991 I took a tour with one of the founders of the association, and was very impressed by the strong feelings he had for the local heritage.