WhyFi

Dude. He's asking if we think that the max PSI rating for the rims, that he recently saw on the LB site, is low. It is low. It would be low for hookless (such as all of the rims in the chart that you posted), but it's absurdly low for hooked rims.

Sy Reene

LOL.. I think we actually agree.. it is low, for any maker of a rim (of any construction), supposedly OK for road use pressures, for a 28mm tire.

WhyFi

The only way that we agree is if you're so confused that you can't convey what we're talking about.

YES. It's very different. You posted a chart of recommended pressures, not one of maximum rated pressure for the rims. He's asking if LB's rating is absurdly conservative. I think that it is, but I still wouldn't have the confidence to take the chance running them higher.

This is incorrect - even some of the hookless Enve rims have max pressure at 80psi. My wide, hookless Zipps have a max of 72.5 psi but they're careful to say that that's a max recommended, not a max for the stability of the rim.

noodle soup

I wouldn't worry about it much, unless the OP is planning on using tires under 30mm wide. I'm about the same weight as the OP, and with 30mm tires(on 23mm internal width hoops) 60/55psi works well.

WhyFi

Again, not the stated question and it specifically goes against the caveat -

If a manufacturer specs 60psi max for their hooked rims or 50psi for their hookless, I'm not going to touch them - I think that it says something about their confidence in their manufacturing and/or research. There are more options out there.

noodle soup

I think they are being conservative.

Their 21mm and 23mm hoops are rated to 115psi. I doubt that their 25mm hoops are significantly different in construction.

Hikebikerun

I’m on the cusp of purchasing a set of these wheels... after speaking with a customer service rep, they thought the AR56-30mm would not fit my 2019 Trek Emonda SL5 due to the rim width.

Does anyone have experience with this? My plan is to put the 28c Conti GP 5000s I have on the stock rims onto the LB rims.

If the 30mm wide rims won’t fit, what about 28mm? LB said they have RR56C03s which are 56mm deep and 28mm wide (21.6mm internal width).

Also hoping to get second opinions on Novatec/Bitex hubs... there was a positive comment on here about the Bitex, but are the DT Swiss 350 a significant upgrade from these two cheaper options?

Also hoping for feedback on the Sapim CX Rat spokes vs the Pillars... for heavy use training wheels, are the Sapims sturdier?

guadzilla

I think so too. The same AR rims are rated to 115psi in the rim brake version - and except for 2 variations, all the disc brake options are now 60psi. Speaking to Charlie @ LB, he said:
"The WR65 can hold 75psi without a problem, I just confirmed with our engineer. But we might lower the tire pressure recommend numbers when it released online to avoid some extreme riders who run with the highest pressure without even consider their actual riding conditions."

I have asked him if the same holds true for the WR45 as well. Still, it would make me feel happier if they felt confident about the ratings. As WhyFi i said, why take the chance?

And to clarify - I dont plan to be riding 28mm WAM on these tires - looking at 32-33WAM. I brought up the 28mm WAM (which i have on my Rovals) to show that the Silca tire pressure calculator matched what seems to work well for me. So that gives me faith in the Silca recommendation to run 32mm WAM tires in the 65-70psi range.

deepakvrao

What's WAM?

guadzilla

"Width as Measured" - a term introduced by 3T but a very sensible way to look at how wide the tire actually is, when mounted on the wheel (eg, my Turbo Cottons are nominally 24s, but measure 27mm when mounted on the Rovals).

Sy Reene

Was the 75psi guidance in reference to your specific WAM of 32mm? Or for the smallest tire this rim is rated for, which is a 28mm (which might coincidentally end up being 32mm WAM?). Again, in general, it's odd that they provide a max PSI on their rims' spec pages, but not labeling these against a specific width tire. Did they reduce their PSI ratings because they DON'T distinguish recommended PSI by tire width?

Eg. For their WR45 rim, 50psi would be more than enough (actually way too high) if running a 50mm tire (max width that rim specs indicate is OK)

guadzilla

The Silca pressure recommendations are based on tire size alone- so presumably WAM. For a 32mm WAM, it recommends a range from 60-68.5, depending on the quality of tarmac - so i am pretty much planning a hair under 65 for the front and a hair over 65 for the rear. A 75psi max rating would give me some additional headroom, that's all.

And yes, you are right- their max PSI ratings dont take into account tire width. I assume it would be based on the least-wide tire that they recommend fitting on the rims (eg, 25c for AR rims, 28c for the WR rims).

noodle soup

Try this inflation calculator, and see if you get the same results.

https://axs.sram.com/tirepressureguide

August West

I wonder when using that calculator if the casing for tires like GP 4000s II or GP 5000 clinchers are considered "Thin" or "Regular"? It makes a pretty big difference.

WhyFi

Yeah, but why? It's not for no reason. Until that's answered, you're assuming unknown risk if you need/want to run at (still quite reasonable) pressures higher than their stated max.

You quite often tell people to toss relatively new tires if a cut brings up any question of safety - it's just a tire, it's not worth the potential hospitalization, just buy a new one. While a current LB owner will probably see this revision to very low max pressures differently, based upon their own experience, for a prospective buyer, this is a perfectly legitimate reason to cull one of these wheelsets from consideration - it's just a wheelset, there are more out there, it's not worth the potential hospitalization, just buy a different one.

Quite frankly, I was very hot on an LB wheelset for some time and I was very interested in hookless, but the lack of documentation, compatibility, etc etc gave me pause (along with the lead times - I'm impatient like that). Seeing this now makes me feel like I made the right move in spending a little bit more for something with better support (documentation and service) and availability. Yeah, I know - YMMV.

Branko D

The R45 disc rims which I have are rated for 130 psi max with 25c tires on the site, tubeless compatible (but I run them with latex inner tubes). The wider AR46 list 115 hooked and 70 hookless, with 25c tires.

It seems their new generation "pro" rims list 60 psi max without tire size, which is all sorts of weird.

guadzilla

Yup, seen that. I have also compared with the Enve tire pressure calculator. They are fairly close one another (+/- 5psi). For a 27mm WAM tire, i end up with recommendations ranging from 82-92psi in each of the cases.

Funnily enough, I set my initial tire pressure using a format posted by Psimet way back when, which left me with 100f/110r for 23c tires. I dropped 10psi for every next size - so 90/100 for 25 and 80/90 for 28s and that worked reasonably well (and also is kinda in the same ballpark as what SRAM, Enve, Silca say).

So for a 32WAM tire, 65-70 seems like a reasonable range.

guadzilla

The AR36, AR46 and AR56 are still rated to 115psi. All the others are now 60psi hooked/50psi hookless, as are all the WR series.

I own a pair of LB AR36 wheels. Really like them and am running them with tubes at 90psi or so (atleast till i use up the S-works Turbo tires).

For me, I'd be ok if they said: "the rim has the strength to withstand the pressure. It is just that we had an issue with someone running XX brand tire of width YY, and for that reason, we recommend a lower pressure just to be conservative". If I had the info, I could do my own risk assessment of whether I wanted to try it or not. But they are being very cagey with their answers, just saying "we are being conservative because we cannot know your riding conditions". Maybe it is a language/cultural thing.... either way, the lack of specific info is putting me off. Especially when different rims in the same dimensions have different ratings.

noodle soup

I think guadzilla is looking at the wrong hoops for his needs, and I can't understand why he wants to run such a high pressure. I thought he was about 185#

noodle soup

the AR36 is also 115psi

WhyFi

Exactly. A little more information with regard to the specifics of the revision would go a long way towards letting a user assess their own risk tolerance.

noodle soup

looking at their narrow 29er hoops I found this "Tyre Pressure 20-40psi recommended". It looks like they are recommending ideal tire pressure, not the maximum tire pressure the hoops can withstand.


https://www.lightbicycle.com/U-shape...ompatible.html

WhyFi

The fact that they say "recommended" for one product makes me think that saying "max" for another doesn't mean "recommended," but rather that it actually does mean "max."

Sy Reene

Going back to your original post on the subject, this is kinda the key bit of info that we don't know.. as apparently this incident caused them to change their PSI rating. If someone was running a 38mm tire at 80psi and it blew off.. then it's not a relevant reason for providing a new 50/60psi PSI recommendation, since as we've noted, it depends on tire width.

The other possibility is they're providing a max PSI (since they only for some reason are providing a single value), that could be used for any tire width that they've indicated the rim can take (ie. 28-50mm).. which of course is a huge difference in direction. This would cover their liability with the lawyers better if that's their impetus for the website change.

BTW.. not sure you've said.. which rim(s) are you specifically interested in, for what type of riding (road/surface)?

noodle soup

After reading some emails from them, you might feel differently. It's clear that English isn't their first language.