First try I made 140km. It was a hot day and the main issue I had was that I sweat more than I could drink. Also it was getting night and I was afraid of not being able to get a train anymore so I abandoned.
For the second try I started at night (2am) to make sure I had a chance to make it in time. Around 4pm after over 180km I had to abandon because the cycle path ended and it was too dangerous to drive on the road with all that traffic.
Anyway it was a very pleasant experience as you pass many nice towns and other sightseeing. I stopped countless times to take pictures. Riding 100km, or even 200km is less harder than many expect it to be.