Does anyone have advice for someone who is returning to bicycling after a multi month hiatus.
I have advice for someone who is returning to bicycling after a multi year hiatus.
It's easy! I used to ride a road bike 50 kilometers nearly every day. Then I just for some reason stopped bicycling for 7 years. I was already somewhat overweight before the break, and far more overweight after the break. I barely did any exercise during the break. I didn't get rid of my bike, though. The bike was stored outside for some of the years so sunlight degraded its brake lever hoods.
When returning to cycling, the only thing I had to do was to inflate the tires. Initially I couldn't find spare lever hoods so I bought gloves to make the sticky hoods less irritating. Then I managed to find spare levers, and extract the hoods from these spare levers and install them to my existing levers.
On the first day, I rode 2 km.
On the second day, I rode 15 km.
On the third day, I rode 22 km.
Two weeks after starting cycling, I already rode 45 km. I think this qualifies to be your "20 mile long ride".
The only thing you'll notice is that the saddle is uncomfortable. It's not due to the saddle. It's due to the break from cycling. Start gradually. My second and third day indeed hurt quite a lot but after two weeks the saddle pain had went away, using the exact same saddle that was on my bike before the 7-year long break.
Even the old chain oil that was already in the chain lasted 400 km after the break. This is because I use a thick wet thixotropic chain lube. After riding those 400 km and finding the chain a bit noisy due to marginal lubrication, I measured the chain and after finding about 0.5% elongation, decided to change the chain instead of relubricating it.