Controlling my back pain is a big motivator for me to ride my mountain bike. However, it took a number of years of experimentation with different mountain bikes and geometries before I found biking to be comfortable and before it evolved into a pain control technique.
I started as a road racer who loved long climbs and stage races. My career ended abruptly during a mountain prologue time trial at the Killington Stage Race. I felt like I was flying up the mountain, having the ride of my life, so I tried dropping my chain into a harder gear. My back and sciatic nerve screamed. I limped to the finish line but dropped out of the stage race overnight. I never raced again. Docs looked at MRIs of my back and declared that they were among the worst that they'd ever seen in such a young person. Frankly, the docs deeply scared me about my prognosis and convinced me that I was going to have to be sedentary. I didn't try to ride a bike again for a number of years.
Over the years since then, I've had two major back surgeries. Both have helped me, but I've been left with an weak left leg and bad reflexes in my left leg (both resulting from a nerve being so badly damaged by discs and bone spurs that it never recovered). I also still have serious neck/arm and headache pain. I've alternated between riding and then having docs scare me out of riding.
Over the past 7 years, I've finally stopped listening to the dire predictions of the docs. One way or another, I need to do what I love. I get only one chance at life, and this is it. I'm not going to let it slip away by being scared of my spine.
A big part of mountain biking becoming a pain reliever for me has been my bikes themselves. I currently have two bikes, both Specialized women-specific frames. I'm very small and Specialized makes the best geometry for me. When I bought my first Specialized (women's stumpjumper 2004), I also bought an adjustable stem. It was an expensive stem but worth every dollar. I experimented and finally dialed in a position that is comfortable. You can see this bike below with the odd geometry of having handlebars higher than the saddle. I also still have the adjustable stem on it. Finally, the black thing strapped to the downtube is my pepperspray which I carry because of my relatively high number of lion encounters. I also almost used it once when a group of coyotes chased my dog, K, back to me.
Another specialization on my bikes is that I get non-stock 165 mm cranks with a 20 tooth inner chainring. The longer stock cranks (175 mm) that are standard on mountain bikes make my hips rock from side-to-side which then makes my lower back bend from side-to-side. I can attest to the serious pain that this causes me over the course of a long ride. The 20 tooth chainring lets me spin when others are lugging harder gears. I use a cadence monitor, and despite the technical and hilly trails that I frequent, I generally average 80-90 RPM over a ride.
This past summer, I treated myself to another bike, a Specialized Safire with a 'Brain'. I absolutely love the Safire. It feels nimble and fast. The 'Brain' reduces the shock compression due to pedaling. It makes a huge difference -- I climb faster, I clear technical trails that I never could ride before, I can fly up super loose and rocky steep climbs, and I don't catch my pedals on rocks anywhere near as often as I did on my Stumpjumper. I probably wouldn't be aware of how much I love the Safire if I didn't still ride my Stumpjumper pretty regularly. The Stumpjumper feels sluggish and inefficient by comparison.
The only problem with the Safire is that the Brain is not set up for very cold conditions, as I discovered during a couple of late fall cold snaps (15 deg or so). However, Specialized was extremely responsive and retrofitted a Brain for me to try out in cold weather. It worked. The very best part was being able to say that "my Brain is currently in the shop" when I did something uncoordinated on my Stumpjumper.
Alas, I love my Safire too much to subject it to the grit and grime of winter riding so it's getting a well-deserved rest in my basement this winter. My Stumpjumper has studded tires and is my current winter steed.
But, there's still a chapter being written. As we speak, Greg at Speedway Cycles is building a Fatback for me. I've been eyeing snow bikes for years but Pugsleys and others are too big for me. The 14" Fatback will fit me, and it'll open up more winter riding to me. I hope to have it by the end of the month! The picture below is not my bike but similar.
My only worry about this bike is that it has *no* suspension. I'm told (and it makes sense) that the huge tires act as suspension. However, today as I bounced along on our dirt road's terrible jarring washboard sections, I was really hoping that the Fatback will have enough suspension for me.