Yes, so I've been thinking (it rarely happens but it does happen!) and figured out why don't I scoop all routes up that I've enjoyed riding on my bicycle and put them nicely in one place for everyone, which (let's be honest here) is pretty much me and ... myself! :) Anyways, if anyone for whatever reason comes to this corner of the Internet (let me dust it off for you real quick, stranger!) perhaps they will find them useful.
I want to start this off with a route that me and my dear friend (yes, it's you!) did a few days back on a nice warm (but not too warm) Saturday. We hopped on a train from Warszawa Wileńska and ended up getting off in Pasieki which is like 2 maybe 3 stations shy of the city of Ostrołęka. Boy, was it worth it! Cool, flat roads, almost no traffic, well taken care of tarmac - can anyone ask for more (other than a company of course!)? Great day, really enjoyed it and hopefully you will too.
Distance: approx. 120km
Time (leisure riding): 6-7h
Road conditions: 99% tarmac, mostly flat
What bicycle: any will do, however road or gravel bike would be my first choice
Here's google map for you: