I gained too much weight and need the exercise. I was going to the gym riding the upright bicycle but I actually prefer riding the real bike out there since riding in the gym is really boring
So I decided to use my real bike again which I had for 20 years now. I did not use it much over the past few years and last year I started riding again more often.
Now my problem started end last year that after several days of riding to work (7.5 miles one way) I developed some strong back pain. Not in the lower back but above the waist line to the side of the spine. I never had this in the past riding the same bike. It was so bad that I had to so a chiropractor. After several sessions with the chiropractor and I was able to get rid of the back pain. I am still going to the gym doing the same back exercises which I learned from my chiropractor.
So a few weeks ago I started riding again. The pain returned. So I thought I needed to change my position on the bike. I never had problems in the gym when using the upright bike. So I modified my real bike to have a more upright position. But the back pain did not go away.
I also rode my mountain bike for a while which has a lower handle bar position just to test having a less upright position. Also here I got back pain.
I am kind of frustrated now since I don't really know how to adjust my bike properly without getting the back pain. I wonder if I should see a back specialist or a bike specialist.
To my person: I am 6'4" and at 293lb. Too much but I am in the process to get rid off it. Already 20lb down from where I started two months ago.
The bike: A European touring bike with 63cm frame size and 28" wheels. Large bike for a large guy. No suspension except the saddle.
My guess is that your weight is a contributor to your back issues. I also have back issues, which are well under control, but I see a chiropractor regularly and spend time each day, almost always first thing in the AM, doing stretching and core exercises and have for many years. I would keep up with chiropractor visits and begin exercises. Maybe seeing a physio-therapist for applicable exercises would be good.