Why not just use regular detergent instead of those pods? Put a little on the door, a little in the cup and watch the magic. Those pods don't get the prewash with detergent and therefore don't get the really tough stuff.
Flout
As someone who's completely self taught over the last 10 years in this industry, I constantly feel like I don't know about these universal principles. I try to make up for this by searching for the best ways to do new things but I often find myself falling back to the lens of my first language. It sucks even though I really love what I do. I can feel the frustration working with formally educated devs and it doesn't feel like there's anything I can do about it. I wish there was a "catch up" class I could take somewhere to learn the most important concepts and review some of these fundamentals.
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!
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