What is the optimum width? Something like EN321? (with 21 internal width I assume) or is going slightly wider even better? Suggest me a rim please.

I run 2.4s on 521s and they're fine. I'd always go for 521s over 321s as they're lighter and not a great deal dearer.

That said, if you can bear going for non-Mavic rims, I understand there are some that are as wide and lighter than 521s.

Mid morn bump

321s or 521s would be fine for that width. I've just gone to Stans Crest from EN321s, and they give an almost identical tyre profile, but save 230g per rim. They're obviously not as strong, but I never really needed the beef that the 321s gave me. If you want tough, the Stans Flow is still lighter than a 521 by some way and arguably stronger – it's also a little wider.

If you want tough, the Stans Flow is still lighter than a 521 by some way and arguably stronger – it's also a little wider

according the the hope site the front is lighter by 74g and the back by 44g, so 'some way' is perhaps arguable but yeah, they're definitely lighter – especially for the width. 2.35/2.4s will fit no worries, though i did break a (plastic) tyre lever getting one of my conti 2.35s on!

i'm debuting a set of hope hoops with stan flows tonight so i'll finally get to see how strong they feel compared to mavics…

looking forward to it.