Quote:
Originally Posted by
Bill Smith 
Ok for the runners in the studio audience, why are Nike Lunerglide 3+s a faster running shoe than the Lunerglide 4+s?
I swear I'm a half minute faster per KM pace wise in my old shoes compared to my new shoes.
Oh, that's easy. You've been wearing down the soles of your 3+'s so they become lighter. Wear them long enough and they'll feel like track spikes. Put a few hundred miles in your 4+ and you'll be just as fast.
Okay, true answer - it varies. Sometimes a shoe can be too stiff initially and fight you in the toe-off. It can also be heavier. And the cushioning can be less springy - some updates are complete fails and I'm looking right at the Nike Span 3 (2002) when I say this - it was like running in egg whites. Also: more than just your shoes could be culpable - variances in speed during the training cycle are not at all uncommon.
For instance, 2 1/2 weeks ago I was turning 89 second quarter miles, no problem. Earlier this week I struggled to keep it under 100. Same shoes.