Smaller packs for smaller climbers?

I'm about to sign up for a 8 day Rainier climbing course to learn the basics of alpine mountaineering, the guide suggests that we bring a 85-100L backpack, depending on level of experience in packing and gear quality (I'm assuming the latter assumes the more expensive gear = lighter and more compactable). I want this pack to be suitable for multiday 6000M expeditions.

So the question is this, I'm 5'6", 130lb marathon runner / Triathlete with a slim frame, and I plan on buying the best (lightest) equipment. Can I get away with say a 60-70L pack? My assumptions are, compared to a 6' 190lb climber, all my clothing will be significantly smaller and lighter, my ice ax will be shorter, sleeping bag smaller, I could probably even trim the sleeping pad to fit my height to save weight and space, etc. If the six foot climber is using a 85-100L pack and all his gear fits, should I not be able to fit all mine in a comparatively smaller pack? TIA

For your Rainier trip, you could definitely get away with a 70L pack. However, if your planning on doing any major +8 day expeditions a +85L pack is a must if your carrying your own gear plus larger packs are only slightly heavier than their smaller counterparts.

Good luck on Rainier!

Make sure you’re properly measured and fit for torso length. Being on the shorter side even a men’s small may be too large. You may have to look at a women’s pack which depending on brand come in xs. Or the Osprey Ace 75 kids pack. Just FYI - I’m a certified Osprey pack fitter. No matter what you buy get measured for that torso length!

A 100L pack?!?  I gotta say that is kinda insane.  I'd ask the guide what gear he uses, the size of his pack and an exact packing list he expects you to bring.  I've done plenty of 10 to 20 day backcountry trips with a full kit (tent, sleeping bag, stove, rock rack, ropes, etc...) and can get it all in or on a 65L pack.  I've done plenty of proper alpine climbs with a 5 day kit and a 40L pack.  

I'm 5'3", 125# and wear XS clothing.  My sleeping bag and clothes are definitely smaller and lighter than my partners but unfortunately not everything is smaller and lighter.

Mark NH wrote: Make sure you’re properly measured and fit for torso length. Being on the shorter side even a men’s small may be too large. You may have to look at a women’s pack which depending on brand come in xs. Or the Osprey Ace 75 kids pack. Just FYI - I’m a certified Osprey pack fitter. No matter what you buy get measured for that torso length!

Hi Mark, I am actually looking at Osprey packs. I measure 17" from iliac crest to C7 vertebra, so looking at the sizing chart would that put me firmly in a S sized mens Aether pro 70?

The Aether Pro 70 is a great pack. Also check out the Atmos 65 AG. The “anti-gravity” suspension is awesome. Make sure wherever you try these they “load them up with sand bag weight” so you know how they carry. Walk around the store as long as you want. Don’t be rushed! Other than properly fitted footwear this is the next best way to ruin a trip - having a pack that doesn’t fit! 

Another factor is price range. My next expedition pack will be a McHale, full custom made to your size, but have to save for a while and a several month build time. Maybe pick up an older used Gregory Denali pack of the frame fits you. Once you iron out the details of packing and know what kind of trips you like then splurge for the exact pack you want.