Be the browser you wish to see in this world

I’ve wondered this same thing. I’ve done 200km before and I did a lot of riding up to the point and I haven’t found the secret other than breaking up my rides a little more as I’ve gotten older. I’ve just always chalked it up to a slightly unfit bike, not the most comfortable saddle and maybe not in the exact right riding position for long enough to matter.

A folding bike sounds brutal and I hope you find a fix!