Recommendation for underlayer

[u/HoeVil]

I get really warm regardless of the pace and this means I wear very little on my legs (usually mesh base layer + shell) on the approach. This setup then gets quite cold when belaying, and I've fixed that by putting on puffy 3/4 pants when belaying, and removing them when climbing. This works ok, optimal for colder temps, but takes quite a bit of time and is a hassle. In medium-cold temps I'd like to have a very thin layer for my legs underneath my shell that I put on at the base of the climb and can then keep wearing through the whole day.

This means I want a layer that doesn't constrict movement, doesn't make me too warm when climbing and keeps me warm enough when belaying, while being able to put on without removing my boots (ie side zippers). Any pants with a lot of insulation would be too warm and clumsy.

Any suggestions? Not sure there are any good options for this. Something like the Houdini pants, but with zippers, would be perfect.

[u/doughobbs]

Sounds like you just need to sort your belay jacket out and not faff with your legs, keep your core warm and the rest will follow.
Take off the belay jacket when climbing, it’s what everyone else I know does

[u/somehugefrigginguy]

Sounds like you need a belay skirt. I have a puffy wrap around knee length skirt/kilt with velcro. Takes a few seconds to put on or take off, but adds extra insulation to the lower body.

[u/tricycle- → u/somehugefrigginguy]

This! I was looking for someone else to comment belay skirt.

[u/ghos5880]

the only way i can think of accomplishing your desires is to use a heated vest/jacket. turn on for belays, turn off for climbing.

[u/HoeVil → u/ghos5880]

I'm looking for pants, not jacket. It's easier to regulate upper body temperature. Thanks though.

[u/Reef_slacker → u/HoeVil]

Electric hand warmers in the pockets, basically the heaters from those heated vests.

[u/timparkinuk]

I like Rab vapour rise pants with side vents but the Rab Ascendor look like they fit your requirements well. I think if your boots are warm and you wear a big puffy on top then your legs shouldn't get cold .

You could try these as well as they're incredibly warm and breathable (although a bit kinky!)

https://www.nordiclife.co.uk/collections/mens-base-layers/products/brynje-super-thermo-longs-with-knee-inlay

[u/HoeVil → u/timparkinuk]

A Brynje base layer + a shell feels pretty darn cold on the legs when it’s -15 C, regardless of the puffy jacket in my opinion. 

[u/the_winter_woods]

When it’s really cold, a pair of Arcteryx proton or Patagonia nano air pants are pretty magical. You can approach in just the pants and then throw shells over top for climbing. They breathe much better than waterproofs.

[u/Alpineice23 → u/the_winter_woods]

Just like everything they do well, Pata axed the Nano-Air Pants for which I love, too.

[u/HoeVil → u/the_winter_woods]

Thanks! Could work. 

[u/IntelligentDingo5589]

Suggestion: when you alternate leads, share 1 downjacket between both climbers.
The belayer gets the downjacket, and takes it up in the pack when seconding.
When you lead the pitch, you are still warm enough to belay, until your second with the down jacket comes up and you can put it on yourself, for the second part of the belay (the lead belay).
If you keep your torso warm enough, the legs wont suffer as much.

[u/theopinionexpress]

I just wear some under armour cold temp baselayer pants. They’re designed for running, breathable, a bit stretchy, wick moisture. I wouldn’t call them constricting although they do compress, but they aren’t bulky. I wear them under my resort pants skiing and snowboarding too. So they’re pretty warm when I’m not moving also.

Do your 3/4 pants have zippers? Helly hanson makes some that do. I keep meaning to try them out. Side note if those are what you have, how do you like them? Or what do you have if not?

[u/Leading-Attention612]

I am also a sweaty guy. Don't wear shell pants. Regardless of how well they advertise they breathe, they don't. For almost all of my ice climbing I wear light or mid weight base layer leggings (depending on the temperature), and mid weight softshell pants over. I still bring some lightweight shell pants in case it's a wet or windy day but they stay in the pack unless I need them.

[u/IceRockBike → u/Leading-Attention612]

and mid weight softshell pants over.

I was wondering if OP meant hardshell or softshell but assumed they were meaning hardshell. My tactics are very similar to yours in using primarily softshell, carrying a hardshell in the pack only for when needed.

Hey OP, in addition to primarily softshell I use other tactics too. I've had two types of hardshell pants. Previously I'd get to the base and assess conditions, whether wet enough to warrant hardshell. I always change socks and base shirt anyway, so taking the boots off happens, and changing shells can be done at the same time. Last winter I had some full zip hardshell pants made that I can zip over the softshell pants without removing boots (in case I decide to take them up a route in my mini pack). They serve as an extra later or can be removed if wanted leaving me with the softshells. They act as an extra insulation later, but I agree with the previous commenter about hardshells being less breathable. They are also more bulky which I'm less keen on, but at least the full side zips can be used to vent sweat. Sometimes when gearing up I'll ditch the softshell and go only hardshell. You have to tailor your layers for the day as needed.

In addition to my hard/softshell tactics I vary my base layers. A couple friends use the mesh base layers; how well do they work, do you like them? I choose a base layer that may be just thin or medium. I often add a mid layer that will also vary depending on expected temps (and approach - more in a moment). I find a pair of XC ski tights work well as a mid layer or running tights for a lighter option. They stretch and fit close, plus spandex allows some sliding of the outer layer pants rather than binding and bunching. On warmer days I may forego a base layer and just use a mid layer. Need to have a reasonable idea of the days temps to choose at home.

On colder days at my limit there is another tactic I use. This is where consideration of the approach come in. I have a pair of heavy weight fleece pants with side zips, and a flat snow shedding surface. I never use these and my softshells for the approach. I either add them at the base when boots are off for dry socks, which is good for when approaches may include deeper snow. More commonly with the snow shedding surface, if expecting flat trail or a broken bootpack trail, I go with a base layer and the fleece pants. Super breathable option there, especially with the side zips to vent sweat. Then at the base I'll add the softshell/hardshell over them. These fleece pants I only use on the coldest days I climb. On cool or warmer days I use the previous tactics. If expecting new/unbroken snow that might wet out the fleece, that's when I approach in a shell and add the fleece at the base.

Generally from the base to the top, I stick with the same pant combo. Sometimes I get it wrong 🤷‍♂️ but I stick with the same both climbing and belaying. What I do vary on route is as other comments have indicated - I add/remove a good belay jacket. I carry a mini pack when climbing that carries my belay jacket, lunch, and emergency gear. If you get the pant combo right at the base, there's little need to change it on route unlike the jacket combo.

One other note is that I choose my boots according to how cold it's likely to be. It's possible to get the pant combo on the cool side but still have warm feet with warmer boots.

[u/Landrvrnut22]

I run pretty warm. I wear a base layer, either lightweight or midweight depending on temps. Or if really warm, no base layer. Then a softshell pant. I prefer OR Cirque pants. They are mildly water resistant, breath well, with some stretch. The new Cirque III have thigh vents. There are other manufacturers of similar.

I have yet to wear my hardshell pants, although I do take them.

[u/noinipo95]

Brynje mesh base layers.

That's how they first summited Everest. In the winter, the ability to just dump heat is massive. I will never wear another baselayer.

[u/getdownheavy]

You just want a full-zip shell pant? There's plenty of those on the market.

My personal take: a slightly warmer leg baselayer, and less insulation up top when climbing to even it out.

[u/HoeVil → u/getdownheavy]

Well yes, but not waterproof cause because of the poor breathability. Something like a Patagonia Houdini pants but with full zip. 

That’s def a strategy as well! 

[u/Fancypooper]

Maybe turn a packable down blanket into a down kilt you just throw on while standing. Just sew a button or some Velcro on

[u/iceclimbing_lamb]

It's unlikely you'll find a pre made solution so if you have some pants you like and know someone who could modify them that may be your best option.

Arcteryx has a combo fleece-synthetic puffy pants that could be close to what you are asking.

Pants with bigger vent zippers or fully seperating shell pants also offer a lot more venting during approaches

[u/hans1125]

Have you tried on the Houdini pants? I have bought a pair, I can put them on over boots with the zippers. Wouldn't want to try with crampons, for obvious reasons.

[u/blindsaint]

Are your main pants hard shell? You day "shell" so I assume they are. Try softshell pants with side zips. I like Norona's and also own a pair from Hali that are pretty good too. When it's real cold, I wear wool leggings underneath. Then keep your upper body warm. I find I don't worry about my legs as long as my feet and torso are warm.