9mm QR Axles - Practical Limits?

My new bike has a RockShox XC 30 120mm fork with a 9mm QR axle. I realize that this is an entry level, XC oriented, fork, and that it isn't as stiff as a 15/20mm through axle fork/hub setup would be. For the type, and amount, of riding I expect to do, I don't think that is going to be a problem.

However, I am curious to know what sort of practical limit a 9mm axle has. Do I have to worry about damaging it, the hub, or the fork if I try to roll over, or off of, something harder / bigger than I should when on trails like the really rooty/rocky sections of Bridle Path?

it really depends on how big you are and how hard you ride.
biggest issue is torsional rigidity of the fork with the smaller wheel.

while i'm on 15mm axles now, i had a qr fox 32 for years on my xc bike, and i'm 95kg. it was good enough for that, and it was before the 15mm axle standards. sure if flip flopped on rough roots, ect, but it held it's own. small jumps, drops, tech are included in my version of xc riding. so based on your post, i'm sure it will do the trick until ( or if ) you upgrade!

i have only broken an axle once, and that was on an old manitou black off the glc drop many moons ago. took the wheel off to put the bike on the roof, and both cones fell out. the QR tension was holding the axle together. it was a squirmy landing though!

I've seen plenty of snapped axles over the years but the quality of the axle is as much to blame as the fork / axle interface. I did plenty of stupid stuff circa 1990 with the likes of Deore XT hubs and can't remember breaking axles (frames on the other hand….).

I broke/bent one 9mm axle in my time. It was on a marzocchi Z1 fr with a double track wheel set up with a Kujo.

Point being, I bagged on that bike riding the shore, the SSC, and whistler.

For the kind of riding that fork should be getting you'll be fine. Maybe notice some flex if you lean over.