Best winter investment since my screaming yellow winter jacket. Bar mitts at 30F have me riding without gloves. Only negative is that you will ride on the hoods. No other hand position. I'm about your height and the medium is OK. A little large, but my jacket fills the gap well enough and I like the ability to quickly get my hand back in after signalling a turn. Can't say about the zipper...guess I never gave it a thought.Now, if I could just find something that kept my toes as warm....