Originally Posted by
Andy_K
Really? I'm not sure I buy that. I've never used road pedals, but I've done centuries using platform-free Egg Beaters and had no comfort problems (at least none associated with the pedals).
Is it just the longer platform that provides the performance and comfort advantage?
You're definitely right with regard to casual riders and commuters, and in these groups MTB shoes have the extreme advantage that you can walk in them easily.
It's a question of pressure. When pedaling, regardless of shoe/pedal choice you are pushing down with roughly the same amount of force, so to change the pressure you feel on the bottom of your foot, you must change the area that force is spread over a larger area. With a road shoe it is spread out over a much larger area (look how much area the cleat contacts on the shoe). Also, since the sole is stiffer, it spreads that force out more evenly over the whole bottom of the foot (while a flexier MTB shoe might give, so you feel it more right under the cleat... although a good MTB shoe with a carbon sole wont have this issue as much). Will everyone notice a difference? Of course not. But there are definite comfort (and performance) advantages that many do notice.
FWIW, my better half rode across the USA twice on cheap, flexy shoes with SPD cleats and didn't have issues, so it certainly isn't a deal breaker... but given a choice between the two on the road, I will take the road style any day just to be safe.