I don't really see it as a matter of efficiency. It's more that I never have to really think about where my feet are on the pedals. They're just always in the right spot and no extra work has to go into keeping them there.

They’re not even that efficient.

I’m curious why you say that. I put clip ins on my bike and it made a world of a difference being able to pull and push while pedaling. Are there better options?

There’s no better option, it just didn’t make as much of a difference as you think it did. They add about 10 percent more power but more at the high end. If you’re pushing 500-600 watts that’s where the difference is clear.

I think the difference is worth it for amateur riders also, stability on the pedals and being able to both push and pull on your stroke should give you at least 15-20% more power. It might not benefit you in your 5Km commute to work, but it will in that 50Km weekend ride.