Updated: Saturday 13 August 2022

This started off as a series of tweets on layer management in bicycle commuting. But, as it is a longer topic than Twitter could handle, I’ll try to elaborate on it here.

In 40 C, even walking for a few seconds’ll generate sweat. And, even in May, you’ll sweat in a car during the few minutes before A/C kicks in.
For now, let’s consider a 25 C sunny day. Not 30 km, since that’d be a dift animal. If you’re learning layering, your commute ought …

— Bike Minder (@BikeMinderOrg) August 9, 2019

First off, context matters. My experience has been shaped by cycling year-round (+43 C to -47 C) in Canada (Montreal, Toronto and Vancouver) and Taiwan, and occasionally in the U.S. and the U.K. And layer management is a topic related to outdoor activities, so skiing, snowboarding, hiking, paddling and other experiences fed into it as well.

Quick How-To

The basic principle is constant monitoring: Always be mindful of your core temperature, and the direction it is heading towards.

• Anticipate what you will have to do. Do not wait till your temperature rises to cozy; vent before you reach that!
• Vent by unzipping or taking off layers;
• As in all outdoors activity, do not wear cotton! Wear mostly synthetics, with some merino wool in cold temperatures. Or merino-only in sustained, cold precipitation.
• All clothing items must be ventable and easy to take off and put on.
• Dress for the season! Thus, no pants/shoes when shorts/sandals would do! No sleeves when sleeveless would do!
• Manage your layers: if venting did/will not suffice, layer down; if a chilly morning, layer up. A few minutes into your morning/evening ride, that extra layer may need to come off.
• A few blocks before your destination, start to cool down: pedal slower, or coast; unzip more, or layer down.
• Upon arrival, take off everything but your base layer. Most sweating occurs when you go indoors, so unlayer before going in. (In summer heat, I even use a hand-fan to cool down before entering. In sub-zero temperatures, I might take off all thermal/shell layers, just to get a large batch of cold air before going in.) Keep in mind that coasting on a bike provides a cooling breeze which ceases as soon as you arrive. Use any wind to lower your core temperature _before_ going indoors.
• On hot days, when arriving at my work-place, I might rinse my face and forearms with cold water, to cool down further. As emphasized above, it is the indoors that causes most sweating.

Is the Above Enough?

Laziness is a virtue. I’d start with the above, then consult the below as things fail! Besides, your practices will vary.

And, no, it is not a complex process: after a while, it all became routine for me, carried out habitually, without much thought.

Commuting versus Exercise

This article does not deal with hardcore exercise; for those, you’re going to sweat anyway! If you’re biking 20 km each way, or climbing lots of hills, or struggling with very windy terrain, this article will not focus on you. Instead, I deal with bike commutes of a reasonable pace. As well, multi-mode and ebikes could benefit from this.

Clothing

Nearly every item of clothing I use is synthetic, with some merino wool for cooler/cold temperatures. The practice is not specific to cycling, but rather stems from general outdoors advice. Inspiration came from fellow engineer, and legendary outdoors guru, Ray Jardine, with sub-zero riding from the ice-bike mailing-list of the early Nineties. As such, I will not go into the reasoning behind the practice; there are numerous resources already available on the Web.

My own variations on the theme are as follows.

• Unlike the general dogma, I rarely wear a tight base-layer; comfort is more important. A loose sleeveless is fine. I am neither trying to shave a few seconds off my time by being more aerodynamic, nor does it make sense for a commuter, or average hiker/skier/snowboarder/etc, to maximize sweat-transport efficiency when 99.9999% of his/her comfort will come from improved layer-management!
• The next layer up may be a very thin, very light, long-sleeve. The chill of early mornings or late evenings makes these very useful. For lower temperatures, thicker ones’d be called for–preferably with a zippered collar.
• The next layer up is typically thermal: fleeces, or merino wool. This is often a mid-layer; but in dry, less-cold conditions, it may be my shell/external/top layer.
• The shell/top layer is where I diverge from most people’s practice. In dry conditions, a Windstopper jacket’d be far better than a Gore-Tex shell: it breathes better; it is in every respect more comfortable; it does not require the care/maintenance of WPBs. If the forecast is borderline, I might carry a super-lightweight shell (with or without a water-repellent coating), bundled into a tiny stuff-sac: this protects against a bit of rain/drizzle, or against an unexpected chill.
• For the top/external/shell layer, a split design would be far better. This is best seen in Windstopper jackets, and in good rain-pants: the front has a shell/laminate whereas the back is made of a thin, highly breathable material. This way, the front protects against rain and wind, while the rear allows all your heat and perspiration to vent.
• Shorts are better than pants. For comfort, you might choose either padded shorts (whether tight Lycra or loose ‘plain’), or a cushy saddle/seat.
• For any shell, whether WPB or Windstopper, pit zips are mandatory. Even if you have a full front zipper, it will not dump core-heat as well as pit zips can–mainly because you can set the pit zips, and forget about them, whereas the front zip will need adjustment in mid-ride!
• All-in-one is bad! If you’re buying a ski jacket that combines insulation with Gore-Tex, you’re wasting your money! The whole idea of layering is that you should be able to separate those two! I see people needlessly sweating, in lift lines, under the Spring sun! The same applies to any other outdoors activity.
• It is a great practice to use lots of small accessories. The ROI of these is great: for a small cost in weight/bulk, you can add a lot of comfort/safety. As the conditions change, you’ll have an emergency option with you, at an insignificant cost (in weight/bulk). For example, I might carry knee warmers, a merino-wool neck-gaiter, a pair of fleece gloves, a pair of merino-wool socks, arm warmers, a super-lightweight/compact shell, or similar, if the conditions warrant it (eg in shoulder seasons, for mountain-top sports, or when the forecast has been varying over the preceding days, or if there is a chance that I might ride back too late in the evening.) The same applies to hardware: reflectors, ski straps, etc.
• If cold enough, a merino-wool neck-gaiter is indispensable. For a negligible cost in bulk, it can add a huge amount of comfort to my ride–either in an emergency, or for autumn/winter rides.
• Zipped is better than pull-overs! I avoid mid-layers which have to be pulled over, rather than unzipped, to take off. The less easy it is to take off a layer, the longer you will wait before you’ll stop to take it off, and so you’ll veer into sweat territory!
• Zipped is better than buttoned. As I ride, I pre-empt heat by unzipping as I go; buttons won’t facilitate this. A jacket’s front zipper may be unzipped partially, or fully, depending on my core temperature. (Or it may be done if I see a hill/climb approaching.) Pit zips get opened/closed, partially/fully, as I go.

Shells

While the above presents an overview of clothing, I’ll elaborate a bit more on shells.

WaterProof Breathables

WPBs are the main category. It denotes the shell fabric used to keep rain/snow out, while allowing the body to breathe (thus stopping heat and perspiration to build up inside). Lots of info available online about these, so I won’t repeat what is available elsewhere.

DWR is the Durable Water-Repellent coating that a WPB is often covered with. It stops water from sheeting onto the fabric, clinging to it, eventually saturating it, and sucking heat out of it.
It can come in a spray can, to be sprayed onto the shell/clothing, or it can be a liquid ‘wash’ used during laundry.
As you use the shell, and wash it, more of the DWR comes off. This is the reason why special detergents are used to wash WPBs with (the goal being to maintain the DWR as much as possible), and why you periodically (eg annually) ought to re-coat your shells.
DWR is applied to the face-fabric of a shell–the part of the clothing that is exposed to the elements.

AFAIK Gore-Tex’s patent expired years ago, which allowed lots of other manufacturers to make clones, under a variety of names. The high-end WPBs still provide the best face-fabric. The WPB laminate is beneath, but it is the face fabric that is subjected to abrasion and the rain/snow. Once that wears off, or its thread loosens apart, it becomes harder for the DWR to stay on.
This is one reason why old shells cease to protect against rain.

However, this is not to say that the higher-end shell is always the better choice. No. I do not know whether I am paying for the material and the craftsmanship, or for the brand name. It is not infrequent that I can get very good quality, at a much lower price. And, worse comes to worst, for the same price, I can get two of the non-top brand, compensating for whatever concerns I might have for the face fabric!
If you have any doubts about what you really ‘need’ to ‘battle the elements’, see what Ray Jardine does with his own clothing kits.

Wind Shells

I’ve touched on Windstopper, above. I’ll emphasize again that, if there is no precipitation, Windstopper is a far better option. It breathes better, packs better, and maintains better. IIRC it costs less as well.
Unlike Windstopper, wind-breakers do not breathe. However, if light and thin, they are far more packable, forming a great rescue shell, or a just-in-case layer to be added if things turn chilly. There are ultra-thin ones which are stuff-sacked to the size of an orange, to be tossed into your pack without a thought.

Merino Wool

There is lots of info available online about merino wool, and I’ve touched upon it, above, as well. So, I’ll add only what is less emphasized.
When dealing with a lot of cold precipitation, whether heavy or sustained, merino wool is a better base-layer. I use it for skiing and snowboarding. But, daily commutes are not day-long; cold moisture does not linger on your body as it would on a day spent in snow. And, frequent washing takes its toll on wool, even if you use ‘the right’ detergent and water-temperature.
So, synthetics remain the best option for bike commuting. Other than for the aforementioned accessories, wool is not a necessity.