My wife gave me Bar Mitts for Christmas and today was my first chance to try them out. The XL size MTB mitts fit over my bar ends perfectly with plenty of room for even heavy gloves. Today I went out in a slightly below zero F windchill wearing only light fall gloves that I would normally wear at maybe 35-50F. I was out for an hour before my fingers even started to get cold. I really recommend these for winter riders. Normally I'd be wearing heavy Ice Armor snowmobile gloves or mittens in this weather.
While I was out, I was wondering, has anyone tried just dropping chemical hand warmers into the bottom of the Bar Mitts? I was thinking of maybe adding an elastic loop inside the mitts near my fingertips to keep a hand warmer in place. I've tried the small warmers, but in water/windproof gloves, they don't get enough O2 and quit working after 30-60 minutes and they tend to heat the back of my hand instead of the fingertips. The medium sized warmers claim to last 8 to 10 hours and with the slight ventilation from the gaps where the cables go through the mitts and the openings at the rear, I was thinking they'd get more O2 than they would inside a glove. There is also a fair amount of air space around your fingers inside the mitts.