I've had a set of Mavic EN321s on ProII's for about 6 years now.
Have had to replace the bearings in them once but never had to go near them with a spoke key.
They've been used with various different axle combinations on a cove stiffee, a meta 5 and a Ti456 they've seen trail centres, natural routes, northshore, drops, uplift days and many a cased landing.
I'd like to replace them with something flash... but there just isn't any point.

