Joined: Jan 2009
Posts: 44,116
Likes: 6,330
From: New York, NY, and High Falls, NY, USA
Bikes: 1962 Rudge Sports, 1971 Raleigh Super Course, 1971 Raleigh Pro Track, 1974 Raleigh International, 1975 Viscount Fixie, 1982 McLean, 1996 Lemond (Ti), 2002 Burley Zydeco tandem
Oh, I don't get that kind of slippage. What I get is basically my feet rattling up and down inside the sandals, not forwards and backwards.
I suspect that too much efficiency leads to fatigue. This is another reason I like combo pedals. I can unclip and then pedal on the uncleated side of my pedals, using alternate positions.