UPDATE: This morning Jorgen rightly called me on declaring the Overshoes watertight before wearing them in the rain. Tonight I put them to the test under the tap. I think Kurt got it right earlier today in the comments. Though some neoprene can be waterproof, open cell neoprene typically allows a little water to permeate the fabric, and that water stays warm when heated by the body. That was the case tonight. The inside of the overshoe got damp, but not wet after 10 minutes under the tap. I didn't detect any leakage through the zipper or top seam.
The mornings got chillier last week. The bedroom floor let me know the score the minute my feet touched ground... it was time to break out Rapha's Merino Hat and Overshoes. For the next four months both will see regular commute action in the season that passes for winter here in California. The Merino Hat is a proven performer, the Overshoes are new.
Getting in and out of overshoes is often their Achilles heel. You want a close fit, but don't want a profanity-laced, death struggle every time you wear them. Tug too hard and some designs come apart. Rapha have done a terrific job getting the fit just right with formidable stitching. I will say I opted to go with Medium even though the Rapha fit chart indicates the upper bound is a size 42 shoe, and I wear a 43.
The black neoprene comfortably accommodates a pair of Specialized BG S-Works with Look cleats. The full-length rear zipper runs collar to heel, and its the primary reason the overshoes are so easy to put on. That said I'm following Don Powell's advice and leaving the overshoes on these shoes for the duration. It's actually quite easy to get in and out the shoes without removing them.
I've yet to get them wet but the snug fit around the cleats and collar (the collar is secured with a velcro closure) leaves little doubt they'll perform admirably. Layered over ventilated summer shoes and winter socks they should be good down into the mid 40s. Below that you might pair them with a heavier shoe like Specialized's Defroster.
Having assured their function, Rapha delivers in the style department as expected. It's a refined look, almost formal with a very nicely placed logo on the outside of each foot and a reflective tab on the heel. Wipe the neoprene with a damp cloth and they should continue to look smart for several seasons depending on how much abuse you give them.
The Rapha Overshoes are available in black, (S,M,L) $70 | £50.00