But you could just ride harder with a smoother chain, or like, carry a pack of gum with you? If you carried an extra water bottle, it'd be orders of magnitude h

But you could just ride harder with a smoother chain, or like, carry a pack of gum with you? If you carried an extra water bottle, it'd be orders of magnitude harder for you than the difference the dirty chain makes. This is hands down one of the silliest things I've ever seen discussed in my decades of being a cyclist and working at bike shops, etc. If you want to exercise there's a million better options than purposefully neglecting your bike.