Folks who develop new sport routes or volunteer to rebolt aging hardware on existing routes haul an inordinate amount of heavy equipment, from cordless drills and wall hammers to pry bars and industrial scrub brushes. Not to mention the wad of heavy chain, mussy hooks, and bolts themselves. When I'm rap-installing a new, primarily bolt-protected route, my pack weight can easily reach 75 pounds or more. The best pack for this sort of work is essentially a haul bag-- a super durable, giant-sized bucket that can fit lots of dense, sharp stuff without sagging or puncturing-- but one that carries comfortably. For many years, I used the Trango crag pack, which still carries weight better than almost any other crag pack out there (so weird for such a bare-bones waist strap and shoulder strap system). However, at 40 liters, it was a good cragging size but a little small for a full day of bolting work, plus the side zip was near-useless IMO. The biggest drawback was that its rubberized fabric was not actually vinyl haulbag material- it was actually surprisingly easy to abrade or puncture for such beefy-looking stuff. Last year, I replaced it with this Blue Ice Moonlight 55, and it has been just great. It has a few improvements that I have come to deeply appreciate. The fabric may not be as thick as a big wall haulbag, but it is plenty strong and durable- I've yet to even see a scratch on it. The bottom stitching helps it stand up on the ground, like a real haulbag, which is very convenient. The extra capacity has been very welcome (although it allows someone like me to consider bringing even more gear, so maybe that's a minus? ha ha). The zipper down the front is great for fully opening up and unloading at the crag-- the fact that you can peel it open very wide at the top and also zip all the way to the bottom means quick access to even the most buried items. Better, the little size pockets, which can expand out just a little, even when the main cavity is filled-to-bursting, are very nice for the approach hike: if I remember to pack my sunglasses, hat, car keys, and soft water bottle in those, I can use the big cinch strap on the main part to stack up ropes, mini leaf blowers, brooms, whatever, on top of the main compartment and still be able to access a few necessities while on the trail without undoing the whole teetering mound of gear. They also help keep your lunch from being crushed :). With 75-85 pounds (which, to be fair, is really pushing the intended maximum for a 55 liter pack-- heck, even an 80 liter long-range backpacking pack is not really intended to haul that much weight), it doesn't carry quite as comfortably on my skinny hips as the Trango did (the weight seems to want to sag onto my tailbone over time), but to be fair, most climbers will not be hauling as much weight, in which case it should be fine. I have added side straps for securing a rope laid over the top and an external clip on the front for my helmet, but again, if you're just day-cragging, even with a big ol' trad rack of doubles, you can probably just fit your rope and helmet inside. The last thing I wish all crag packs had (that I also added to the old Tango): a tote-bag style handle-strap on the top front, so you can pick up the whole pack by some handles (the usual pick-up handle between the shoulder straps plus the other one on the front) and move it from spot to spot on the ground in the upright position. The duffle bag-style handles on the front of this pack get close, but for me a horizontally-oriented one would be the most useful (would have to be click-openable or something, though, to allow the front zipper to open all the way). All in all, though, this pack is a real powerhouse, and I would definitely buy the 40 liter and 25 liter versions when my current cragging pack (the old Trango) and my little climbey daypack finally give out.
