first of all i'm sorry, but the following links are all in german, can't help it. but as you're there now, i guess you'll get along.
i would recommend the heckmair route over the transalp challenge route anytime. far better landscape and trails, although you'll carry your bike a hell of a lot.
here's the wiki link for the heckmair route and this is the book where we got the infos for the transalp route.
as we did this first in 2000 and the second time in 2008 we used actual maps, but i guess tempus fugit and the gps thing is the way to go. the wikilink has a link for this too, the book had a CD with it, i guess it contains something similar.
i rode my bike a lot in preparation and although being a lazy DHer at heart i clocked up a massiv (for me) amount of km's. i lived near stuttgart at that time and rode a lot on the schwäbische alb. but to get used to really long ascents we went and did week-end trips to the alps or the schwarzwald to ride a lot of vertical meters at once, as the ascents in the alps are rather longish. i also trained every once in a while with a backpack loaded to approximate weight of what i would carry along with me, as i usually don't ride with backpacks that big (30 l, ca. 8-9 kg).
go and get one of those ultra nerdy german bike magazines (BIKE, Mountainbike), they have a yearly returning transalp fury that's kind of bizarre, but there are usefull infos like packing lists on them.
bike wise just be sure that your bike is in a good shape, not too heavy but still robust enough to take a beating. i think ca. 120 -140 mm rear travel should do the trick, i would not use a pure race whipet, rather something like a specialized carver / stumpjumper
if you want / need more detailed infos let me know.
Sweet, good info...if you think of anything else please add in. May be buying a new Cube this spring w/ TA in mind, but also my run with my Altitude 70. A guy named Crazy Larry is planning this, so it should be interesting...
Any good places along the route you reccomend for eats/scenery/vino/massage/etc?
Stuttgart ODR has some MTB rides when the weather is warmer. I would look into that for getting back on some local trails first (unless you already ride local).
I'm bouncing between Grafenwoher, Stuttgatrt, and Mannheim @ the moment, and don't ride too often any more. I hope Weisbaden has some nice rides this summer as thats our final stop and will stay there for a little more than a year.
Check out the LBS's around the area, and the bookoo website. I have seen some nice GHOST bikes and even a stumpjumper for sale on there. You can get some decent prices when people need to unload before a deployment or PCS. Picked up my car for 800 bucks
question for you germany knowing folks,
hows the riding secne in the southwest Schwarzwald/ frieburg area? ill be there fora year starting in fall and stoked to bring the bike out. and hopen to get some mega gnar alp rides in too
there's a DH trail from the Schauinsland peak with a cablecar from the city center and there's a good DH / FR park in Todtnau, which is more or less around the corner... For XC (or whatever the actual acronym for riding up and down a mountain at the moment is...) there are a abundance of trails around freiburg and in the Schwarzwald.
here's a link to the biggest german mtb forum, it also has local subforums.