I’m building up a pair of wheels with Mavic EN821 UST rims. They’re the type with the fully covered rim bed – no spoke holes. Thanks to the ever helpful Roger Musson I’m all sorted for building them up using the screw in cups and everything, but I’m not really sure what I need to do for different tyre options. So here’s some questions I hoped some one would have some answers for.

If I run tyres with tubes (I know it’s a bit silly but I’ve got them available at the moment) do I need any rim tape and if so what sort?

If I run proper UST tyres do I need any rim tape and do I need any sealant?

If I run non-UST tubeless ready tyres do I need any rim tape and do I need any sealant?

Cheers!

You won’t need tape on any combination. They are fully sealed rim beds. If you run proper ust tyres you don’t need any sealant. I ran mine like this for a couple of years until I got my first puncture. I started adding a bit of sealant just for puncture protection. If you run non ust tyres then you will need sealant to seal the tyre and for puncture resistance.

Thanks for the info Andy, I was hoping it would make things that easy, but couldn’t quite convince myself it would!

It’s a much better solution than tape. Even though I have a few sets of taped rims it always seems like a bodge. I haven’t had any problems with the taped rims but sealed beds are just nicer. Ust does have a weight penalty with the extra nipple inserts but I’m not really that fussy about weight.

Weirdly when running a set with tubes I kept getting punctures from the rim bed. Never figured out how as there was nothing to see in the spot the punctures occurred. Bit of electrical tape sorted it

I always ran mine without tape. Works identically to tubeless rims with tape, just weighs a bit more tbh… But they were fine with tubes, fine without tubes. And pretty unfussy about tyres- they were a little overtight but I think the only tyres I ever had that wouldn’t play ball, were those useless undersized schwalbes a few years back.

With UST you don’t need sealant but it’s pretty silly not to use it IMO. You’re obviously not a weight weenie, because you’re using 821s, and that’s the only benefit to going without sealant- but you lose so much benefit.

Don’t be put off tubeless ready tyres either, UST rubber’s a bit of a dead dog these days, for good reason.

Thanks all.

I couldn’t seem to find much in the way of full UST tyres and as by the sounds of it I’m better off using some sealant anyway I’ll keep an eye out for some general tubeless ready ones.

Cheers.

I have heard that some combinations of tyre/rim the inner lip of the UST can pinch the tube as the tyre flexes.

Dunno if its an urban myth or not as i’ve never seen it myself, but it sounds plausible.

The only thing I’ve found with them is that non-UST tyres don’t seat & seal very easily.
They get there but it’s been quite a faff with 2 sets of tyres on mine.

You’ll be fine with any if you’ve got a compressor though.

I am using these rims with Specialized Purgatory tyres. No tape, bit of sealant and they work perfectly. No issues getting the tyres on and they inflate with a normal track pump.

If you dont mind the slight increased weight UST tyres are worth looking for, I have a UST Maxxis Ardent on one of these rims and its not lost any pressure yet, I’ve not even got round to adding the sealant yet.