Doge

I didn't do so well on my tire thread. Maybe there is some advice on this.
Given the same ratios, so with a 32T front we'd have larger cassette teeth in the rear than with a 28T front - which is preferred 32T or 28T?

I know 28 we have about 200g less mass and 32/28% of the stress from chain tension to compression on the chain-stays etc.

This is for a hard tail (and does it matter?), 150# rider.

prathmann

More teeth for greater durability vs. fewer teeth for less weight. Not sure why you put the per cent sign in there (it doesn't belong).

Reynolds 531 

The problem is in the rear. Any reduced friction from lower tooth count in the front, will be MORE than offset negatively by the smaller rear.

A smaller rear sprocket causes the chain to articulate more as it tries to wrap around the smaller sprocket, which creates more friction from the chain pivots.

The negative of this (9 tooth is particularly bad) more than outweighs any friction advantage from wrapping "14" front teeth compared to "16".

disclaimer: I know there are studies. I know there are watts. I also know that this is infinitesimal, but the guy asked a question.

Final analysis: A racer will be better served by putting an extra hour per week into interval training instead of spending an hour calculating frictional losses.