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I'm running a set of Hope XC 29er wheels on a new build which is essentially a sort of gravel/monstercross/frankenbike affair for mixed road/off road riding.
It's my first tubeless set up and I'm aware that some rims have max. pressure limits (separate from those of the tyres) as I believe that tubeless tyres can pop off the rims at higher pressures.
I'm currently experimenting with 700x45 WTB Riddlers which feel a little draggy on tarmac (compared to the much heavier 26" semi-slicks I had on my old bike) so I'll be experimenting with psi (and maybe other tyres).
I can't see a max. pressure warning anywhere on the Hope rims or on the Hope website (although I have emailed them for clarification) but wondered whether anyone was aware of one.
The Riddlers are rated 35-55 psi.
I've had 80psi in mine with a tube and 35c clincher tyre. I didn't die.
I won't be going near 80psi except for seating the tyres. The issues isn't with a tubed set up but I was under the impression that some rims [url= http://singletrackworld.com/forum/topic/stans-rim-pressure-warnings ]such as Stans[/url] have max pressures for tubeless set ups (sometimes as low as 45 psi) to prevent tubeless tyres blowing off the rims (I've no idea why tubed tyres don't run the risk of popping off in the same way).
I can't find anything relating to Hope rims and thought that it would be useful to check if they had any as I'm possibly going to go over 45psi.
I asked Hope the very same question. Reply I got was about the same as a crest!
I think the max pressure with Stans is to stop the tyre casing tension from ripping the bead wall off the rim or splitting the rim. That would explain why they quote lower max psi’s for bigger section tyres.
I might have misunderstood what I've been reading but the max. pressures for rims seem to relate specifically to tubeless setups and the possibility of tubeless tyres blowing off the rims at higher pressures; it seems that tubed setups are not susceptible to this.
I can find very little relating to this and Hope XC rims (and I don't recall seeing anything marked on the rims themselves). I take it that wider tyres will have lower max. psi ratings that narrower ones; hopefully my 700x45 (roughly 29x1.8) Riddlers will be okay at 45-50psi
Just trial and error then until I hear back from Hope. Has anyone actually had a tubeless tyre come off the rim whilst riding?
That’s exactly what burping is, Just with a few more revolutions/ more force.
Be aware that some mtb rims over the years have been known to physically fail due to pressures exceeding design spec too - actual rim failure not ‘just’ tyre blown off. It’s one of those things that hasn’t really been much of a problem as the trend has been to lower pressures. In a sense, you’re off the design map putting 700’s on a rim designed as a mtb 29er not a road or cx. The actual size of the rim may be the same but that doesn’t mean it was designed with the same capabilities in mind. That said, 29er rims have a long history in CX. There are CXers around these parts, but I think I’d be asking on other forums too if you aren’t already.
But we are talking tubeless specific yes? I get the impression that tubed setups aren't a problem (eg Blazin-Saddles 80psi 700x35)?
I've no idea why tubed tyres don't run the risk of popping off in the same way
Because the tube helps keep the bead in place.
Also, read back about 5-10 years on amateur rim reviews. Plenty of pressure related issues with people overinflating mtb tyres with tubes.
It’s a problem for bigger people (not necessarily overweight, I knew a 6’6” guy built like the proverbial outhouse who gave up mountain bikes because everything was too lightly built to survive)
You’re looking at a problem with multiple issues here. Pressure alone can and does cause tyre and rim failure, but there’s also plenty of potential for failure due to incompatible beads, unsuitable tyres due to construction and simply bad luck and user error. Lightly built rims can also be a problem, barring exotic material properties.