In the UK a decent winter cycling jacket isn't a seasonal accessory, it's an all-year-round essential. The weather's unpredictable enough in lowland areas - get up into the hills and literally anything could happen. And probably will. Here are some pointers to help you choose your winter jacket wisely…
Waterproof is easy. All sorts of things are waterproof - tarpaulins, rubble sacks. But if the thing inside the waterproof gives off moisture as well then you've got a problem. A sheet of polythene is waterproof in both directions. Wrap it round something like, say, a hard-working cyclist and chances are they'll drown in their own sweat. Even if they don't, if they stop working hard because they've got to the top of the hill they'll cool down very quickly thanks to having a layer of condensation right next to them.
The challenge for a good waterproof garment is to stop rainwater coming in but letting moisture from inside get out. As you'd imagine, that's pretty tricky. Fortunately it's not impossible. The reason that it can be done is because the stuff you're trying to keep out is actual water droplets, while the stuff you're trying to let out is moist air - it's just got lots of water molecules in it. If you switch on a shower in a cold bathroom you'll get lots of steam and condensation as the hot, moist air hits cold surfaces like mirrors and tiles. Switch it on in a hot room and you won't - it just stays as hot, moist air. So the usual waterproof fabric trick is to somehow engineer a fabric with lots of tiny holes in it that are big enough to let molecules of water through but not big enough for raindrops.
How they manage this depends on the fabric. Gore-Tex and its imitators use a synthetic membrane bonded to a chemically-waterproofed fabric. The waterproofing on the outside is known as the Durable Water Repellent (DWR) layer, and it's this that causes water to bead up and roll off. Without it rain soaks in to the fabric and clogs the membrane so it won't breathe as effectively. On heavy-duty jackets the membrane will be between two layers of fabric to protect it (known as three-ply construction). A common weight and cost reduction strategy is to leave the second layer off (two-ply construction).
Gore-Tex itself has been refined and improved over the years, with a number of variants offering improved softness, durability, breathability, light weight or combinations thereof. At the same time several manufacturers have developed their own fabrics working along similar lines. These are often highly effective and generally cheaper than the original Gore-Tex, but won't match the performance of Gore's high-end fabrics like XCR.
Other do away with the membrane altogether and rely on engineering the actual weave of the fabric to do the same job. This can make for very light, very breathable jackets but it's an expensive solution.
Jackets are one of those things where the old maxim "you get what you pay for" still generally applies. With few exceptions, the more expensive a jacket is the more breathable it will be…
When it comes to waterproofing and durability, the fewer seams the better. Joins between fabric panels represent a weak spot both in terms of water ingress and garment strength. The problem is that it's harder to make a well-fitting jacket the fewer panels you use, so a compromise has to be struck. Stretch fabrics like that used by Karrimor allow them to get away with fewer seams without compromising fit and freedom of movement, but the fabric's expensive. Seams should always be taped internally to stop water getting in through what is, after all, a row of holes.
Heavy-duty jackets will nearly always have some form of liner, often a simple mesh affair. This serves two purposes. First it protects the actual waterproof fabric from abrasion from the inside - this is less of an issue if a three-ply fabric is used but such fabrics are heavier and more expensive. Secondly a liner puts something else between you and the inside of the main fabric. If you manage to exceed the ability of the fabric to transport moisture out to the atmosphere you'll get a build-up of condensation inside. If there's a liner there, though, you might not even notice. Jackets made with highly-breathable fabrics often do without.
With the widespread use of packs and the popularity of riding in trees (or amongst trees for the pedants), it's worth considering jackets with some added reinforcement. A lot of high-tech waterproof fabrics aren't all that resistant to abrasion or tearing, so beefed-up areas on the shoulders, tail and sleeves are popular. Whether they're necessary depends on your riding style and preferred trails. If you tend to snag your existing clothing get something sturdy…
Fit's always a tricky one for cycling-specific waterproofs. Designers of walking jackets have it relatively easy - the customer is generally standing up straight. Jackets suitable for climbing are a trickier proposition, what with strange posture and harnesses to allow for. But cycling is a nightmare. The rider could be down on the drops of a road bike, all stretched out, or perched upright on a freeridey MTB. And if the latter it's only a matter of time before he or she decides to drop down a steep bit and stretches their arms out to get some weight back.
There are a few common strategies to deal with all this variation, though. Most bike-specific waterproofs have a short front and a long back to allow for the common leaning-forward position. More MTBish jackets are fairly conservative here, but roadie jackets are often very short at the front. Try them out in your usual riding position. Too long at the front and you'll get uncomfortable bunching. Too short and it'll all be a bit draughty.
Similarly, if you lean forward more then you may benefit from a longer back, but sometimes you can have too much material back there and keep getting it snagged on the saddle as you shift your weight forward on climbs. If you run mudguards of any description then you may not need as much of a dropped tail.
Some jackets have a stowable drop tail which can make the garment somewhat more versatile. Different manufacturers have different ideas on all of this, so try a few out sat on a bike and see which ones suit you best. The same goes for sleeve length. Generally bike waterproofs have over-length sleeves to allow for your arms being extended most of the time, but depending on the length of your own arms you might find that they've under or over-done it.
Another area where manufacturers differ is on simple sizing. Some will size a jacket as, say, a Medium but will allow for a base layer and a couple of fleeces so it might feel large and flap about in the breeze. Conversely they might make no allowance and you might end up with something too snug. There's really no other option than going in to a well-stocked shop and trying a few on. Take your usual base and mid layers and go for a fit that's not too flappy with just a base layer but allows room for the mid layer.
One of the problems with British weather is that it's quite often wet but relatively warm. Breathable fabrics rely on a substantial temperature gradient between the inside and the outside to transport moisture outwards, but if it's not actually all that cold outside the jacket then there's often just not enough thermodynamic wotsittage going on to make them work effectively.
For that reason most jackets also feature some form of mechanical ventilation. In fact, every jacket we can think of has at least a front zip. Obviously that's there primarily so that you can get the thing on and off but if you're getting a bit warm then pulling the zip down helps a lot. Velcro-fastening cuffs are also commonplace, letting you snug them up to prevent water and wind ingress if needed but also giving you the opportunity to run them a little looser for a bit of a cooling breeze up the sleeves. You can even push the sleeves up if it starts getting really warm.
Jackets made of the more breathable fabrics sometimes leave it at that - zips cost money, after all, and more breathable fabrics are more expensive so leaving off as many things as possible can make the difference between an vaguely affordable jacket and a preposterously expensive one.
Underarm "pit zips" are a common venting strategy on jackets, though, allowing direct airflow to potentially sweaty bits. If they're there they need to be long, ideally with a double zip so they'll open or close in either direction. Some jackets have a mesh panel inside the zip, others just hang open - which you prefer is really personal preference, although mesh has an irritating habit of getting tangled up in the zips.
Cycling waterproofs range from super-simple, ultralight smocks to full-featured jackets. What you choose depends a little on what sort of conditions you're likely to encounter. If you're looking for a jacket primarily to carry just in case then you'll want something lighter with fewer toys. If you're a wet-weather riding fanatic and after a jacket to actually go out in crappy weather in regularly you'll probably be after something a bit meatier.
We've already mentioned Velcro cuffs and zips, pretty much universal features. Pit zips are common but not universal. Nearly every jacket has at least one pocket, but pockets are one of those areas where user opinion is strongly divided. Some people like lots of pockets, others prefer to have everything in a pack and as few pockets as possible. We're somewhere in between - we find a simple chest pocket useful (although only if it's big enough for a map) but don't get on with low-down front pockets and always find our packs get in the way of rear pockets. A rear pocket with a side entry is occasionally handy, though.
Hoods are another controversial fitment. Some would argue that what with helmets and hats they're a bit unnecessary, but in a real downpour you're likely to change your mind. There're a couple of approaches to hoods. Either they're big enough to go over a helmet or they're snug and designed to go under one. Both look odd but the under-helmet approach has the benefit of better visibility, not blowing around in the breeze, being easier to make and using less material so it packs away more effectively. Some hoods stow away, some are removable and a lot of jackets don't have one at all. Your choice.
Drawcords at the bottom of the jacket and the collar let you close up any draughty gaps, but they need to be easy to use. We like the one-handed toggle-lock style ones. Some jackets save money by only having a cord pull on one side, worth watching out for if you're a left-hander.
Colours present something of a dilemma. From the point of view of visibility, whether you want to be seen by motorists or rescue helicopters, bright colours are best. But with "visual impact" often cited by the anti-MTB brigade and, lets be honest here, the vagaries of fashion, a lot of jackets go for more earthy, subdued tones or indeed black. You'll nearly always find some reflective piping, trim or logos on jackets to brighten things up in the dark, but if your primary use of a jacket is commuting we'd go for something bright. The subdued look is fine in the woods (no-one'll see you anyway) but we'd rather take our chances with the fashion police than with articulated trucks…
Care & feeding
What with most waterproofs being (a) made of high-tech synthetic fabrics and (b) expensive, it's worth taking care of them. The problem with most of the fabrics in common use is that they rely on the DWR (durable water repellent) treatment on the outer surface to make water bead up and roll off rather than soak in. It works a treat, but the detergents in your household washing powder tend to wreck it. Additionally several manufacturers don't recommend machine washing or demand a low-temperature wash. This is all bad news if you like to just chuck everything in the machine and press the button.
It's entirely possible to get away without washing jackets for quite long periods of time. If you put it on because it was raining then the rain probably kept it fairly clean. If you run Crud Catchers and Race Guards then not too much splatty mud will have found its way on to your jacket. Even if you don't, there's often just a bit of gunge down the back that you can just rinse off.
But there comes a time when you have to wash the thing, usually just before you run out of friends to ride with, but more importantly because if it gets too dirty the magic breathable fabric stops working. Follow the manufacturer's instructions, which will usually forbid the use of detergent - there are various specialist cleaning products out there but good old-fashioned soap flakes work just fine. Some manufacturers recommend a cool, brief tumble dry or iron to breathe new life into the DWR - again, follow the instructions.
If you do manage to kill the DWR then a trip to your local outdoor shop should get you a wash-in or spray-on retreating solution to get things back to full beading potency.