Bioflex's Sub-Zero overshoes are designed purely for keeping you warm rather than keeping out water. As you can guess by the name the Sub-Zeroes are designed for use in freezing conditions thanks to a neoprene outer with a fleece lining.
Straight off the quality looks very good indeed with no gaps in seams or frayed stitching. I get through at least one or two pairs of overshoes a year but little touches like a rubberised toe cap and twin pull tabs for getting them on and off easier should hopefully see these last a little longer than the norm.
They are regulation black but have a few reflective highlights to get you seen and thanks to the thin material they don't look overly bulky, more like oversocks than overshoes. The YKK zip is at the rear like most which makes them easy to do up plus a storm flap at the top adds some water resistance.
There are four sizes, S-M-L-XL starting at 36 up to 48 of which the test ones are a large and my size 45 feet are right at the maximum of the 42-45 band. This did means things were pretty snug but after five weeks of virtually daily use there has been no issues with the zip being under strain. The only issue there has been is with the zip on the overshoe sitting directly against the one on my tights causing some rubbing on my Achilles.
The toe is another place where I find a lot of wear usually, the short walk from car park to office causing most of it but the rubber toe-cap here has shrugged all of that off so far with not a single blemish.
Underneath you'll find two large reinforced holes, one for the heel tab and the front for your cleat. Bioflex say they are compatible with all cleats and judging by the size I can't think of anything that wouldn't fit.
While the temperature hasn't been super chilly yet a couple of foggy early mornings have seen the Garmin showing just 1-2 degrees and with just standard summer shoes and socks under the overshoes, my feet have stayed warm. Layering up with merino socks when the temperature drops below the freezing mark should see little change but we'll keep running these through the winter to see how they get on and update here.
As mentioned at the start of the review the Bioflex Sub-Zeroes aren't intended to keep you dry in a downpour and if you do get caught out in the rain you're looking at only 15 minutes of riding on a very wet road surface before water starts to come in through the material. Thankfully though the neoprene keeps your feet toasty warm even when soaked.
The price of £29.99 seems reasonable when taking the quality into account but bearing in mind the Sub-Zeroes only tackle one half of winter's riding issues. There are others on the market for a tenner less that'll do their best to keep you dry as well.
Overall then a very durable, lightweight pair of overshoes that look good and will fit any cleat type. Performance is looking good so far with regards to the temperature but we'll keep updating you on how they get on through the winter. They're up against stiff competition that includes some form of water repellency.
Impressive quality and cold weather performance so far but only for the cold-but-fair weather cyclist.
road.cc test report
Make and model: BioFlex Overshoes Sub Zero
Size tested: Black L
Tell us what the product is for, and who it's aimed at. What do the manufacturers say about it? How does that compare to your own feelings about it?
The Sub-Zeroes are designed for freezing/dry weather conditions and Bioflex make a lot of noise about how durable they are and to be fair they are holding very well indeed.
Tell us some more about the technical aspects of the product?
Extra durable winter overshoe provides warmth in freezing conditions.*Extra durable fleece lined
*Neoprene fabric with integrated gripper.
*Reflective heel panel for increased safety at night and low light conditions.
*Hardwearing toe cup reduces wear while engaging pedal cleats.
*Twin Pull tabs ensure a quick and easy fit.
*Water resistant YKK concealed zip
*Fits all shoe and cleat types
So far so good but we'll keep running them throughout the freezing months of November to January to be sure.
Can be a zip clash issue with tights but no more than other overshoes using the same design.
Good price for the quality and looks but lack of wet weather protection could see them struggle against cheaper competition which do both.
Tell us how the product performed overall when used for its designed purpose
We haven't had cold enough temperatures yet to really push them but as far as durability, fit and build quality go they are very good.
Tell us what you particularly liked about the product
The thin material and looks.
Tell us what you particularly disliked about the product
The zip position has seen some clashes with heel zips on my tights which did prove quite painful at times
Did you enjoy using the product? Yes.
Would you consider buying the product? Yes.
Would you recommend the product to a friend? Yes.
About the tester
I usually ride: Ribble Winter Trainer for commuting, Genesis Flyer My best bike is: Sarto Rovigo
I've been riding for: 10-20 years I ride: Every day I would class myself as: Expert
I regularly do the following types of riding: time trialling, commuting, club rides, sportives, fixed/singlespeed,