border crossing czech republic

The German-Czech border is 650 km long. Currently there is only one autobahn crossing anyway. But there are also pedestrian only crossings. No idea if this will change from 21. December 2007 on when the border controls will be abolished.

would be a great help to know from where are you starting out????

If it's from the area of Munich drive via Deggendorf to Bayerisch Eisenstein and on to Pilsen, most direct route, no autobahn, beautiful landscape, but still considerable traffic (though way less than via Furth) - there are smaller ones like Phillipsreuth, Haidmuehle etc - but that's not the most direct route (but nice landscape)

keep in mind:most direct route means that any commercial vehicle will take the same route...

riding... as in bicycle... or motorcycle?

if bicycle... there are great bike/walking paths along some rivers...

I had an interesting river crossing (pedestrians and bikes only) somewhere along the Elba (?) river, not very far from Dresden.
Don't know if you plan to go that far...

There is the Elbe Radweg if you're cycling or walking. It follows the Elbe all the way from as far north as Hamburg through Dresden and into the Czech Republic.