Well I guess I'm in the minority here, because I tried using both hand and toe warmers this past weekend...and my feelings were that they did not work very well. I was wearing Smartwool cycling socks and stuck the toe warmers to the bottom of my socks as instructed (after activating them, of course). Put my shoes on, as well as my Pearl Izumi AmFib shoe covers. I felt the warmth for maybe 30 minutes, tops. Perhaps the Smartwool socks were just too thick to transfer the warmth...I don't know.

As for the hand warmers, I didn't feel them at all. I wore a thin glove liner with a pair of Descente Wombat gloves. I placed the hand warmer between the liner and glove, on the top of my hand. I never felt any warmth whatsoever. On top of that, it was extremely difficult to get the placement of the warmer in the correct position once you have 1 glove on. You almost need to have another person shove the warmers up into your gloves for you, because it's just simply impossible to do once you have 1 gloved hand.

I personally, will not bother with using the warmers again...at least not for cycling purposes.