Originally Posted by
Tony (Michigan)
If it were me, I would first ask the doc if riding a bike would make the bulging disk worse. If not, and I had what you have, I would probably get a bike that uses larger wheels than the skinny road/race tires. My larger tires on my other bike are much kinder on my back. They pump up to a max 80lbs. My road/race tires max at 120lbs. Every little bump is felt at 120.
Adding to the above, stay away from aluminum frames. The wrong material for a road bike. I've always stayed with steel until I went with titanium. Carbon fiber can be better depending on the construction. Titanium is good at shock absorption but is more lively than carbon. I use 25 mm tires @ 120 rear, 110 front and the bike is unbelievably comfortable even with a stout carbon fork designed for cyclocross.
Having some arch in the back helps protect from shock as well. I prefer a 45/50 deg back angle myself both road and mountain bikes.