Having used these for a couple of months now I've found they make very little different in terms of how my hands feel biking in winter. Still cold, perhaps slightly less than without these but not much. And they make it much harder to get your hands on and off the handlebars, which could pose a safety issue in certain situations. In short, I am puzzled by all the 5-star reviews since in my experience these, while not exactly useless, did not solve my cold hands problem.

These make your bike look silly as all get out, but you wont mind, because your hands will be inside with liners, or nothing at all and they will still be warm. I rode on a 20F degree day with these bad boys on and my summer gloves with hand warmers in them, and they were TOO hot... while it was 20F out... Ill deffinitely ride with a fashion fauxpas attached to my bike if it means my extremities are warm! Now I just gotta find something similar for my feet!

Controls of the shifter and brakes is not affected by these covers. However you should be comfortable with control positioning before attempting to ride with these on, as they will block your view. Getting your hand in and out of them is extremely easy, as they hold their shape quite well when installed and stay put once the velcro straps are secured tightly. Installing them on the bike took less than 2 minutes per side.

I was initially worried that the hand openings were going to be too small, and that the mits would be too tight on the handlebars. I've come to find that they need to be somewhat snug in order to help retain heat. These mits work great when wearing a light pair of mittens or gloves (I have large hands), but are difficult to slide heavier gloves/mittens into. Once "on" though, these mits really have done the trick in providing that extra layer of protection against sub-zero temps. I've ridden at -13F with these and a pair of heavy mittens have been good. Great price, would recommend.

These are surprisingly warm! Much better than just gloves in the cold. Around 20F, I was able to go bare handed on my bike ride; any colder than that, and light to medium gloves are recommended.

PROS:
-Warm
-Lightweight
-Easy to Install with short brake levers
-Same performance as another brand that's charging over $100 a pair for mitts made from the same material
-Looks better than other bar mitts
-Only goes to your wrist or just past it

CONS:
-Opening for hands is on the small side, so people with bulky gloves or super large hands may have fitment issues
-Still looks kinda dorky
-Hard to install if you have long brake levers

P.S. Sorry for the blurry image. My camera kept fogging up!

They're pretty small. From the pictures you think they would be bigger but they're not and that is its only real downfall as it makes it somewhat difficult to put on your bike and a little awkward putting your hands in when you're wearing somewhat large gloves.

The part of my bike that I use to change gears is a part of the handlebar where I can just twist it up or down to change it; I haven't had any issues changing gears.

I have used these in 14 degree Fahrenheit temperatures so far with a my usual winter gloves and a non-insulated glove underneath meant to just wick away sweat and they're absolutely wonderful. My hands and fingers never get cold anymore! For a few weeks I used hothands, which also worked really well but those made my hands sweat more and they started to tear apart the seems on my gloves forcing me to buy new ones.

Despite the size I'm giving it 5 stars for being good so far down to 14F degree temperatures, not even including windchill, and for the affordability. These definitely make cycling in these kind of temperatures more comfortable! I'll use these in the single digits and teens but anymore than that and I'm just going to wear gloves. These are incredibly warm.