The summer is not over but not many good weekends left! Coming WE looks good so far and I'm planning to do www.vennbahn.eu the old railroad turned into cycling path, quite flat. From Troisvierges to Aachen it is 125km, but I plan to do just 100km to Eupen on Sat, sleep in a hostel there and cycle back on Sun. It is possible also to take the last train from Eupen via Liege to Lux city after 7pm on Sat, takes 3.5h. Or continue 25km to Aachen and catch train from there.
Departure is by train from Lux city to Troisvierges on Sat morning.
The hostel has only a few beds free. Feel free to message me to discuss trip details.