Originally Posted by freeskihp
so flipping the stem, bad or good idea?
Flipping the bars is a good idea for pretty much any pain. It looks like you saddle is all the way back and those bars don't allow many good hand positions except far forward. If the pain continues you may want to get a shorter stem or some road drops. If the saddle is not intentionally set that far back you could move it up too BUT adjusting the saddle is the wrong way to fix reach issues if it's corectly adjusted now. Also aero bars with risers are very comfy especially if you are going to be doing the century brakeless and therefore not drafting.
While it will suck, if you cannot ride 40+ miles without pain DO NOT attempt a century. You may finish it but you will likely end up injuring yourself and being out of commission for a while. There will be more centuries to do next year unless you have a large bet on this one or don't ride during the winter it's not worth it.