Got a feeling I might have purchased the wrong rims for my new wheelset. I went for a set of Hope Hoops with Stans Crest rims, set them up tubeless and loving the lack of rotating weight and low pressures. The downside is that the rear feels quite flexy, I think it is the tyre moving around on the rim (Nevegal 2.2) as it is a relatively large tyre on a relatively narrow rim. I have upped the pressure to 35 PSI and it helps a little but not much. The other option that has crossed my mind is that it is the rim flexing but it happens at such a low speed I don’t think it could be.
The question I have got is if it is the tyre moving around would a smaller one solve the problem and if so how much smaller? Or would Arch rims be better. Not sure I want to go as far as Flows because the masterplan is to save the set of Pro2/DTSwiss 5.1 I have for anything aggressive.
I weigh approx 85kg in gear and am riding a Blur LTc. Any advice gratefully received.

It won’t be the rim, unless you’ve a real crap build.

More likely is that you are just not use to them yet. For reference I’ve current the Crest/Pro2 set and run a 2.35 Ardent on the rear at 25psi tubeless on a HT. Only once it drops below 20psi does it feel unstable.

The crest isn’t a narrow rim.

It could be a bunch of other things too, of course:

Tyre choice

Spoke tension / build

Tyre pressure

Not used to tubeless

QR tension – wheel shifts in dropouts

Wheel bearings shot

Suspension linkage bearings shot

Shock bushings shot

Too many pies

Try borrowing a friend’s rear wheel to see if you get the same problem. If not, put the Nevegal on it and see if the problem comes back. Try your wheels in a different bike, and see if the problem replicates there. Add more air, or stick a tube in. Change one thing at a time, ride and repeat.

In short, don’t jump to conclusions about the rim – try removing or changing one aspect and seeing if that changes things. As a side note, I sold on a perfectly good Magura / Stan’s Olympic wheelset a few years ago because I found it simply too flexy when loaded into corners. The tension, round and true of the wheel were flawless, but I simply didn’t have the same squirmyness when I put the same QRs and tyres / tubes on a different wheel.

Thanks for the replies,
The wheelset is brand new, the rear end of the bike feels properly attached (and was solid with the previous wheel) so I am pretty happy that it is not the bike or the hub. Spoke tension appears ok. As to the pies very likely but by extension that means I need to change something else or get used to the feel of them. The QR tension is ok (checked and rechecked), but I may well not be used to the tubeless feel. Next time out I will try with a tube in if that is the same then at least it will be something eliminated.

Are they the 24 spoke ones? I have a 24 spoke front hope hoop that would feel decidedly flexy if I landed it off something, and generally a bit noodly.. I think they’ve got a weight limit, which I’m nowhere near, but I tried it on a couple of bikes with different forks and got the same feeling.
I bent the rim and replaced it with an old Bontrager Race Lite rim which is about 100g heavier.. And now it’s a world of difference! The bike tracks better, and doesn’t want to go sideways on landings.

If you’ve got a frame as stiff as a Blur LTC then any lightweight wheel will tend to feel flexy. It’s got to take the strain somewhere!