Bullshit. I have used them for the past 3 or 4 years (INCLUDING on rollers) and I have fallen exactly once and in my defense, my front tube exploded so I was kinda distracted by that. As for using them on a mountain bike FIRST ? Even more poppycock - you are more likely to fall riding a mtn bike so clips are even less useful there (for me at least) and really, dirt is softer ? How about roots/rocks etc. ?