Product Code: RK-40-CC-SS



The RK40 is a bigger version of the RK30. As well as its extra volume, it also features internal sleeves that give you the option of inserting two tubular titanium frame stays (available separately). These make the pack more comfortable if you are lugging heavy loads (e.g. a big rack with a couple of ropes). This is the new 2020 model and features a new removable front/side compression system. 

The RK40 is available in two back lengths - Regular and Long.






Accessory pocket at rear
Removable front/side compression system
Oversized back haul loop – easy to grab and clip
Top compression strap
Two ice-axe holders
Option to fit two stays to stiffen back carrying system
Welded construction throughout - fully waterproof
38 mm webbing waist-belt

Technical Specifications

Capacity 40 litres
Weight 1050 g
Fabric 40% Kevlar / 60 % Cordura, 240 g/m²
Frame Option for two 7.00 mm Ø tubular titanium frame-stays (not supplied with product)

R (regular)
L (Long)

Spares & Repairs

If you break any buckles or your frame stay (it does happen), then don't panic. We have replacement parts for nearly everything. Please go to the Rucksack Spares section of our online shop.

Crux rucksacks don't often need mending, but they are not completely immune to abuse. Should your sack ever need repair, then please click here for details of our recommended repair agents.


There will be full stock availability in both colours and sizes from November 2018.

Delivery & Returns

All our products are shipped with UPS for quick, reliable and secure delivery. As most of our products are quite large and/or of high value, they will require a signature. We cannot deliver to P.O. boxes. All orders are dispatched the next working day after receipt (Monday to Friday). Typical delivery time is 2–3 days.

If you change your mind about your purchase, you can return it unused for an exchange or refund, provided it is within 90 days of receipt of your order and the item is still in its original packaging.

Knowledge Base

For more information about our backpacks, please click on the following links below.
Sizing and fitting of crux backpacks
The physics of backpack design