If you don't mind me asking Steve... why the past tense? Why not still ride?
I don't have a super-short answer but I'll explain as best I'm able.
Before my back injury, I ran, swam, and bicycled. As I returned to health, I realized I needed strength and began strength training. As I began deadlifting, I noticed a pattern as regards my back, bicycling, and deadlifting. Here's how it works for me.
I do very little stretching of my lower back. My problem originates with lax connective tissue in my lower back - it was weak and overstretched from whatever I did in my life up until age 42, and although it's no longer weak, the damage that's been done to tendons and ligaments is done. My back, as a rule, doesn't generally feel great, but it's acceptable - I must leave it be a little on the tight side for it to work properly in my activities of daily living.
Now when I ride a bike, my back _feels_ better because it gets stretched out very nicely, but it functions worse. In particular, I wake up that night with leg cramps, which are really phantom leg cramps because it isn't muscle fatigue that causes them but rather it's pressure on the nerves to my legs that run through my lower back. And I've also noticed that deadlifting just feels plain wrong right after a bike ride, and even the day after a bike ride; I have to wait a couple of days before I can deadlift again.
So if I ride a bike, it means derailing my weight training and potentially causing me a rather painful, sleepless night.
After my back blew out, I was on Percoset 24/7 for 3 weeks. I don't ever want to live like that again. The medicine would work for about 2 hours at a time, so I'd sleep for about 2 hours at a time, and, well, you get the idea.
I can ride once in a while, if I don't do it for very long and if I don't do it again for at least a few days afterwards and if I don't mind not lifting. That kind of schedule doesn't happen for me very often, and I don't try to make it happen, either. I'm content with my slightly stiff, amply strong lumbar spine, thank you very much.
-S-