icemilkcoffee 

I just had a custom wheelset built with Kinlin XR26T rims. Last night I snapped on the Caffelatex rim strip and put a Gravel King tire on there, and quickly found out something very disappointing: When the tire deflates, the tire bead will come off the bead shelf. The Kinlin rim doesn't have the little ridge on the edge of the bead shelf to keep the tire bead there. I see at least 4 problems:

1. I need to deflate the rear tire to put it into the frame. And with tubeless, you can't just re-inflate a tire. You need to re-seat the bead first. With this particular rim, I needed soapy water around the tire to get it to seat the first time. And that was a brand new tire and brand new rim with no sealant. When there is dry sealant all over the tire and rim, it's going to be much harder to seat.
2. Some of my bikes sit unused for weeks or months at a time. If I let this sit unused it will deflate and leak sealant all over the garage floor. And I park the unused bikes in an area of the garage where my compressor air hose can't easily get to.
3. If the tire runs flat during a ride, the tire is liable to come right off the rim like a regular clincher tire.
4. At one point I ran ghetto tubeless with a Mavic Ksyrium wheelset. It set up well but I experienced two episodes where the tire burped and leaked out a significant amount of air, in the middle of turns! After the second time that happened I went back to tubes on that bike. Will this new wheelset experience the same kind of sudden burps and air loss?

At this stage I am questioning whether I even want to go tubeless with this wheelset. But then I looked at the very popular Velocity Quill rim and the Pacenti rims, and I notice that these other TLR rims also do not have the bead trapping ledge. So how do other people deal with TLR rims with no bead retention? Do you just commit to keeping the wheels inflated all the time and never take the rear wheel out of the frame?

Just for eye candy: Kinlin XR26RT off centered rim on 126mm FH1055 hub. Gravel King Slick 700x43c

Iride01 

If you look at the cross section of the rim on the website you'll notice that the bottom of the bead seat angles as it goes toward the inside of the rim. So that lis making for a slightly larger diameter that the bead has to deal with. Perhaps not as effective as a actual bump.

What about your rim strip? Did you get a size that doesn't lap over so far that it goes up the side of the bead seat? For my tubed tires BITD, I never cared for the rim tape to even be up on any part of the bead seat. But for my current bike that is tubeless ready other than valve stem, it doesn't seem to bother me that the tape or rim strip they used is up on the bottom part of the bead seat. Though I do have a tad more trouble breaking the bead than in the past.

Perhaps some of the issue is that you just didn't give it much time to remain inflated before you released the air. Since you have these, give it a try for tubeless and see what happens when it actually happens or at least go a month or two of rides before you start assuming stuff. And at that time let the air out and see what happens. Particularly since experiments like you did, don't always adequately cover all the variables.

icemilkcoffee 

Yup. That was exactly what I thought when I ordered the rims. But in real life, the slope of the bead seat is either very, very slight or non-existent.

That's the other iffy thing in my new wheelset- the Caffelatex rim strip. It goes wall to wall, and it's very thick. I believe it is SOP to have the rim tape wall-to-wall. But the thickness of this rim strip is worrisome. For starters- I can't hear any 'snap' when the tire seats. It just gradually stop leaking (but not entirely since I have no sealant in there). Very weird. I don't know what to think about these strips yet.

Yeah I'll probably end up doing that just because of sunk costs. But I just want to hear how other people deal with this particular issue.

Andrew R Stewart 

My short answer is to not run those rims tubeless and if you have to be tubeless get a rim that interfaces with the tire in a more positive manor.

Burping air on cornering is a "too little air pressure for the set up and use" thing, IMO.

Really if the set up isn't working for your needs, or how you deal with your bikes, it's time to move on to what does. Andy

icemilkcoffee 

Yeah. I'm already eyeballing the Alexrims AT470. It seems to be the only silver rim with bead retention ledges. Still, there must be a LOT of you out there running tubeless on Velocity Quill and A23's, Pacenti, DT Swiss R460, etc rims with no bead retention. I can't be the only one who notices these things. How are the rest of you dealing with this issue?

grumpus

Extra layers of rim tape?

squirtdad

what size tires are you using....

as I read it, rim specs say 21 to 28 mm https://kinlin.com.tw/xr-26t/

icemilkcoffee 

I have a 43mm Gravel King Slick on there now. The plan is to run 43mm front and 38mm rear.
I don’t think the tire width affects the bead retention though.

Andrew R Stewart 

IME you would be wrong. Very wide tires mounted onto a narrow rim does increase the bead's ability to slip up/off the rim edge and allow the tire to burp. But you already knew that as you posted about previous burping experiences with a skinny road bike rim. Perhaps you just didn't listen to your experience enough.

Tire retention loss as tires get wider and wider is but one reason why many tire/rim companies have their own suggested width range charts. Andy

Kontact

1. You chose the wrong rim strip. Certain tire/rim combinations require thicker rim strips to work right, and tape strips are the easiest way to make that happen with additional layers.
2. A properly seated and sealed tubeless tire will remain seated if you deflate it. See 1.
3. Tubeless cannot be expected to sit around for months at a time. The fluid pools in the low spot and congeals. You need to ride more often than that for tubeless to be useful, regardless of the tire and rim combination. If you want the bike to sit without problems, use tubes.


Get some tape and build up a thick enough layer to make the bead pop when seated. The XR26T is a normal enough tubeless rim design that this shouldn't be an issue.

icemilkcoffee 

The Caffelatex rim strip is VERY thick. Almost touching the rim hooks. Are you saying the tire should stay on from friction with the tape? What exactly is keeping the tire on if there is no ledge?

You are not wrong. I'm exaggerating when I say sitting for months at a time. But on my kids' tubeless setup, they have certainly gone a whole month without touching their bikes with zero issues. In fact with Orange Seal Endurance I only add sealant every 6 months or so. I rarely have to pump their tires. That's how well the UST Mavic Crossroc rims seal against the UST MTB tires.

Kontact

There is a ledge. You can see the ledge in the cross section I posted - it even slopes toward the bead to keep the bead seated. That's a XR26T rim.

I haven't used Cafelatex, but I suspect that either the thickness and texture is a factor in why the bead isn't staying in place. Maybe the belt is too spongie, maybe it is moving since it is not adhesive. But 2-3 layers of adhesive Notubes or Stan's always works. And it should work with nothing more than a little soapy water, which is a good way to start out if you are unsure how many layers you need.


Tubeless can and will work after the sealant dries up. You won't know it is dried up until you get a puncture and it fails to seal.

bboy314

Agree with this, I think you’re really pushing the limits with tire size and that may be contributing to the problem.

squirtdad

based on the ERTO tire and rim should be compatible.....What pressures are you running? a 43 with a load of rider, bike and stuff of 260 lbs would have the following range from the rene herse calculator
Soft: 43 psi (3.0 bar)
Firm: 54 psi (3.7 bar)




W

Kontact

So he can go to 55mm since the rim is 19mm internally.

icemilkcoffee 

thanks to all for chiming in. There were two schools of thought here. Andrew et al thinks the wide width is causing the bead to drop, while Kontact thinks the Caffelatex rim strip’s thickness and non-adhesive nature is to blame.
In the spirit of science, I change the rear wheel with the Caffelatex strip to a narrow 28mm GP5000 TR and pumped it up. And then I taped up the front wheel using traditional Stans/Kapton tape, and put the 43mm Gravel King on there- This time I got the satisfying ‘Pop’ when the tire seated. With the Caffelatex strip I never got a pop with either tire.



I set the wheels aside and let the air leak out (no sealant). And as you can see the 28mm tire on the Caffelatex strip dropped the bead. The 43 tire with the regular tape stayed on with the bead still seated after the air leaked out. I was able to pump it back up with a hand pump with zero drama.
So the conclusion is that the thick Caffelatex strip interferes with the bead seating. Maybe it works for some other combination of tire and rim, but at $35 a pair I can’t afford to do any more experiments with Caffelatex strips. Good ole fashion tape for me from now on.

Spoonrobot 

Tubeless rim tape is generally 4-6 mils thick. The Caffelatex rim strip is 31 mils thick. It's a product from another time before TC, TCS, TLR, etc. Not for modern rims, as you have determined for yourself.

The major circumference of the bead seat. It's how Stan's rims generally "worked" so much better than other tubeless rims - their BSD is slightly larger than the ISO spec for a given rim BSD. The benefit of tubeless rim "bead lock" features is questionable/theoretical - given they cribbed the name from a feature found on motorized vehicle rims.

This is a real bead lock:


This is a marketing feature that may or may not function as described:

Kontact

In all fairness to Cafelatex, this product is primarily a conversion strip to make normal rims into tubeless:

https://www.effettomariposa.eu/en-us...less-rim-strip

icemilkcoffee 

The ledge works extremely well. It works so well that it's almost impossible to unseat the bead with your fingers on my sons' Mavic Crossroc wheels. Luckily on the Mavic rims, they purposely have one small section, directly opposite from the valve hole, where they ground down the ledges. This is the only spot where you can push the bead off the shelf.

Spoonrobot 

UST bead retention device is a specific design and not the same as a generic bicycle "bead lock" - UST is what Mavic uses being the originators of the design and standard. This standard was also designed to be used without tape or strip. Covering any retention devices with tape reduces their effectiveness. Manufacturers apparently are using the ISO for the UST bead retention device but without using the rest of the UST design features, which does not work as well or at all.

What people often perceive as the bead being locked onto the bead seat (from a bead retention design) is mostly tension from the bead. Kevlar and other aramid fibers used in bicycle beads can shrink or otherwise constrict during use. I had a WTB tire where the bead shrunk/constricted/tightened ~2mm and it was almost impossible to remove by hand. When I finally got the tire off and cut the bead it relaxed violently, explosively fraying from both sides of the cut.

The bead can also become trapped under the bead hook and rims with a low G height but large "B" length often are not circular hooks but have a hollow under the hook where the rubber can expand and effectively grab onto the rim resisting force perpendicular to the rim sidewall.

Regardless, like many things, whether they work or not is left to determine by the user. Being the bicycle industry, there's apparently no quantifiable data to evaluate.

"The average of tires of type A, in width B, at pressure X through Y, force required to unseat the bead with bead retention device is H, without bead retention device is H minus 1.2N" - wouldn't that be nice? Of course, we know, from the recent hookless debacle that manufacturers can do such, they just won't unless forced.

Spoonrobot 

If you remove the other tire and rim strip can you post a photo of the XR-26 rim bed?

It seems like the rim drawing for that rim is understating the "beadlock" and making it appear there is none at all - when in actuality I suspect it is the same as the other tubeless Kinlin rims and there is a discrepancy in the rim profile drawings, not terribly important but would be helpful reference for others who may find the thread. The TL-23 features a very mild bead lock and on-ramp, I have a TL-23 that I cut to cross-section for reference and such features can clearly be seen, and are present on the drawing.




However, I also have some XR-31T rims which have a drawing the same as your XR-26T, without the bead lock feature pictured as so. But this rim has the exact same design as the TL-23.

Andrew R Stewart 

"Andrew et al thinks the wide width is causing the bead to drop" - icemilkcoffee

No, I tried to suggest that a way wide tire (compared to the rim width) will help the tire bead not contact the rim as well as they should and increase the chance of burping/blow off. This is the opposite of bead drop, or at least in my world. Andy

icemilkcoffee 

Here is the XR26T before taping:



There is no ledge whatsoever. And unlike what the engineering drawing suggests there is no discernible slope neither.
interesting that the XR31T has ledges.

Kontact

You don't need a slope or ledge for tubeless. The fact that the shelf has the bead under tension is enough - especially once you have tire pressure and sealant acting as a mild adhesive. I can see why a downhill rider would want ledge for extra security, but for a 43mm tire at pressures over 30 psi there is no need for the belt and suspenders.

Sy Reene

FWIW, I think the UST system was so 'locked in' that you weren't even required to use sealant.

Isn't this circled area a ledge?


No ledge would mean a design like the left-most one in this diagram