Originally Posted by
SBRDude
Regarding bike tourers, pure conjecture on my part.
Regarding lower back pain in general, I got that from poking around on the web because I tend to get lower back pain after about 2 hours. Since that's usually about the time I stop for food and water, I do a quick stretch and I'm usually fine for another hour or so. Anyway, I was hoping I could do something to get rid of that pain (I already do a fair amount of abs and core work), either through exercise or bike fit, and everything I came across said it was a very common problem even among those who race for a living and it was the result of being in a bent over position for such a long time and putting pressure on the back or hip flexors that weren't meant to be bent for so long.
"Conventional wisdom" folks frequently repeat what they've heard, rather than write from personal experience. That's a big reason for a lot of foolishness on the web. The traditional road bike position with bars even with or lower than the saddle is that way because it's easier on the back. It's also more aero, but the larger reason is that it's more powerful and comfortable over the long haul. The reasons for this are very simple. The biggest reason is that our backs are much comfortable when they can respond to loads by flexure rather than compression. The more upright, the more your spine is loaded in compression which is exacerbated by riding a bike on bumpy roads, and all roads are more or less bumpy to a bicycle. The second is that back flexion opens the dorsal side of the lumbar vertebrae, which decreases pressure on the nerves and the facets.