I think the set-up is very important. I sturggled with the wrong sized frame for a year, getting lower back pain before I got it sorted, requiring a new frame in the next size up.
I've have friends who have almost had to give up cycling, until they discovered that they really needed to get their set-up right.
The very nature of the act of cycling can really cause havoc on your body if you've not sorted your position. imo.
Theres a set-up in one of the Zinn books, which helps people get to a good, general position, from which they can then make minor alterations to zero their final set-up.
I set-up as follows:
1st Saddle height
2nd Saddle Fore-aft
3rd Reach
It helped me.
🙂
Solo