While there is certainly a viable case for opting for a pair of the best winter bib tights, my preference is instead to use a pair of thermal bib shorts and a set of leg warmers. For me, it makes for a more versatile setup, especially in changeable conditions.
There's more to the best leg warmers though than just a pair of stretchy tubes. Fit is important, as are the grippers; not too tight that they are uncomfortable, but not so loose that they slip down embarrassingly. My preferences all come from a solid winter of testing in some incredibly bleak weather; wet, windy, and cold. Durability, wind resistance, DWR coatings, and fit were all put to the test and one pair was a clear winner.
My first choice is the Pro Sl II from Endura, as they somehow tick all of the boxes and come in at the more affordable end of the spectrum.
The winners
Best overall
The primary reason I love these leg warmers is the fit. They're articulated so avoid the annoying bunching that often plagues the back of the knee. More than that, though they're good and tight, especially on the lower leg. The ankle doesn't have a zip, only a raw hem, so there's no hope for slipping them off while your shoes are still on, but the flip side to that is you get a next-to-skin feeling for the whole leg and no pressure points if you layer some overshoes on top.
The upper thigh grippers are wide and tenacious, without ever getting to the point where they feel like they're more of a tourniquet than a garment of clothing. The rear of the upper leg is more fleecy to cosset your precious hamstrings, while the front, especially the lowers, is more windproof. Add to this a decent DWR coating to help keep rain and spray at bay and you're onto a winner.
While many others offer 'reflective details', which usually amount to little more than a small reflective tab, these have large, visible patches on the back of each calf. All things considered, and even exclusive of value, these are the leg warmers I'd take out with me over all others.
Best value
These are, to all intents and purposes, two black tubes of stretchy, fleece-backed material. For many of us, especially for a first pair for very intermittent use, commuting, or even mucky duties like cyclocross warm-up laps, that's all you really need. I wouldn't want to wear these for a mega day out, but for a first pair, especially at this price, there's little to fault.
If you start to ride more frequently in cold weather you will probably find you want to upgrade them, but if that's the case you won't have lost much. That being said I owned a pair of these for years, and they just kept going for far longer than I expected.
Honourable mention
At the other end of the spectrum to the dhb Regulate is the snappily names Assos RS Leg Warmers Targa, hereby referred to as 'the Assos ones', or some such. They wouldn't necessarily be my first choice regardless of price (the RRP is very steep for leg warmers, admittedly), but they definitely have a place.
Unlike the Endura set, or most others on the market, these are constructed from a thinner, more breathable material. The result is that, despite having limited articulation in the construction, they achieve a sublime fit by dint of the material itself. They are noticeably more breathable than other options too, despite not being any colder. For long days out where it may well get a little warm in the middle of the day, they were brilliant, not only for this reason but also due to the comfort factor.
Leg warmers aren't always comfy; you're adding an extra gripper to an area of muscle that's working hard and moving a lot. The Assos pair get around this with a raw upper hem, devoid of any gripper, instead relying on a cut that goes all the way up the outer thigh to the hip, and an array of silicone dots to hold them in place. They're not so secure as the Endura pair, but they are more comfortable in this department.
