I think I replied in this thread a while ago but it is still going


I used flats for decades and switched to clipless a few years ago on my gravel/road bike. In my opinion, efficiency, slipping or not, comfort, ease etc comes down to what you are used to and your style. I never as far as I can remember ever slipped off my pedals with flats, that was BMX, MTB, and road bike under all kinds of conditions. Now that I am "used to" clipless and actually built up a trust for them and not just something to hold my feet in one place, I actually do slip or at least get a little light at times on occasion when I go back to flats. Interesting transformation. I still use flats on my MTB but if the trend continues of relearning, I'll probably eventually increase using clipless there too.

In the end in my case I can't say one is better than the other. What clipless did for me along with some other changes and conditioning was get to a higher cadence average allowing longer days with little to no knee pain. I was always a masher but after not riding much for a while and getting back in, mashing didn't work for me anymore above 40 or so miles or sequential days. Maybe that would have worked itself out with or without clipless, who knows. Either way I am using them now.