Problem - Need some input from a road tubeless guru..

Everything about building wheels, glueing tubs, etc.
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jahknob
Posts: 118
Joined: Tue Sep 07, 2004 1:27 pm
Location: London, UK

by jahknob

Hoping someone with more experience than me can help with a problem I've been having - it boils down to two wheels, prepared identically and set up for tubeless - one holds air and the other doesn't and I want to know why this might be.

Here are the details - it's a pair of Rolf Prima VCX wheels and Schwalbe One Pro 28mm tubeless tyres. Both wheels carefully cleaned and prepped, using the Tesa tape that's been recommended on various forums, wrapped around the rim twice.

I've used the Effetto Mariposa tubeless tape when I used this set-up last year and had the same problem as I'm now experiencing.

Once the valves are in place and the tyres on the rim, I have checked the tape to ensure that it's still perfectly positioned with no wrinkles or movement. Inflating with an Airshot reservoir doesn't automatically seat the rim bead in place; I have to pump the tyres up to about 120-130PSI before they're set. I haven't used any soapy water to help the bead seat and there's no sealant used yet.

One wheel has remained completely airtight for more than two weeks. The other deflates completely in about a day. When I looked at the rim tape on the deflated tyre, it was wrinkled and pushed down towards the centre in several places. I took the tyre off, took off the wrinkled rim tape and taped it again. This time I put the tyre on with an inner tube and pumped that up to 120PSI and left it overnight. Took the inner tube out and checked the rim tape - it was perfect - no signs of air bubbles or movement, and it appeared to be stuck down tight. Reinflated as tubeless and within a day it had deflated and the rim tape is a mess again.

I'm not sure that the rim tape has moved enough either time to be the cause of significant air leakage (hasn't come close to uncovering spoke holes, for example), but I don't understand why it moves at all as the tyre deflates...

I know that when I put sealant in to the tyres, this will be less of a problem BUT last year, one wheel stayed inflated for weeks and weeks and the other would deflate in about a week if I didn't pump it up regularly - and because the Schwalbes don't stay seated on the rim bead when they lose air, the sealant leaks everywhere if I don't remember to keep them pumped up.

Can anyone offer an explanation for why the rim tape moves as the tyre deflates, whether this issue is significant and what I can do to try to ensure that the problem wheel/tyre will produce a decent seal?

One more point - I swapped the tyres over to compensate for wear. Although I don't know for sure, I believe it's the tyre rather than the rim - the problem tyre does have a tiny nick (less than 0.5mm) at the very bottom edge of the bead, was wondering about using some sort of glue/filler just to make that edge perfect again, but this seems too small to have such a significant effect?

Would welcome your thoughts on this...

by Weenie


zefs
Posts: 137
Joined: Sat Aug 05, 2017 8:40 pm

by zefs

Are you using the same valves since last year? it's recommended to change them each year, maybe try swapping them to see if it will fix it?
If you think it's the tire swap them again and test.

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IrrelevantD
Posts: 359
Joined: Sun Nov 29, 2015 5:47 pm
Location: Near DFW Airport

by IrrelevantD

Been running road tubeless for about 10 years now, not going to say I'm an expert, but I have a lot of experience.

First question; are they still deflating rapidly with sealant in them? I'd consider 2-3psi/day normal, anything more than 15psi in a week with sealant in them to indicate something isn't right. If you're not using sealant, I'd say that a tire holding air perfectly (again, 2-3psi loss/day acceptable) to be luck, or good fortune, with a taped rim. I'd expect that from a true tubeless rim (doesn't require tape), but I'd be OK with a little loss through the tape as sealant should fix it.

Personally, I haven't used Tesa tape, I've always used Stan's, and I have one pair of wheels setup with Hed, but I wouldn't worry about the wrinkling. The bigger concern for me would be how much the tape deforms into the spoke holes. This will come into play when you replace the tire. I've found that Stans deforms a lot making it harder to re-mount the tire, I replace the top layer every time I re-mount tires. The Hed tape is a bit stiffer, it looks more wrinkly, but I've replaced the tires multiple times on those wheels and am still on the original tape I installed when I bought the wheels.

Second question; what is the rim joint construction? Is it welded, pinned, sleved? I've found that non-welded rims are kinda hit or miss. I have a pair of wheels I built up with Kinlin rims (sleved) in which one holds air very well, the other lost tons of air through the joint. Again, sealant solved that issue by shacking it arround with the joint at the 6-o'clock position.

As Zefs suggested, might take a look at your valves as well. Some designs perform better than others. I've had Stan's valves last me years with the wedge at the base, whereas I've had Roval ones, which have an soft plastic o-ring, end up completely worthless after a couple of tire changes.

As for the tire not staying on the rim bed, that is concerning. I run Pro One 25's on my Hed rims, which don't have a lip to help keep the bead on the shoulder, and I don't have this issue unless some other force pushes on the sidewall to slide it off. I supose it's possible that the sealant is helping to keep it in place on the shoulder.

Hope something in here helps.
* There is a 70% chance that what you have just read has a peppering of cynicism or sarcasm and generally should not be taken seriously.
I'll leave it up to you to figure out the other 30%. If you are in any way offended, that's on you.

MikeD
Posts: 151
Joined: Thu Dec 11, 2014 9:55 pm

by MikeD

jahknob wrote:Hoping someone with more experience than me can help with a problem I've been having - it boils down to two wheels, prepared identically and set up for tubeless - one holds air and the other doesn't and I want to know why this might be.

Here are the details - it's a pair of Rolf Prima VCX wheels and Schwalbe One Pro 28mm tubeless tyres. Both wheels carefully cleaned and prepped, using the Tesa tape that's been recommended on various forums, wrapped around the rim twice.

I've used the Effetto Mariposa tubeless tape when I used this set-up last year and had the same problem as I'm now experiencing.

Once the valves are in place and the tyres on the rim, I have checked the tape to ensure that it's still perfectly positioned with no wrinkles or movement. Inflating with an Airshot reservoir doesn't automatically seat the rim bead in place; I have to pump the tyres up to about 120-130PSI before they're set. I haven't used any soapy water to help the bead seat and there's no sealant used yet.

One wheel has remained completely airtight for more than two weeks. The other deflates completely in about a day. When I looked at the rim tape on the deflated tyre, it was wrinkled and pushed down towards the centre in several places. I took the tyre off, took off the wrinkled rim tape and taped it again. This time I put the tyre on with an inner tube and pumped that up to 120PSI and left it overnight. Took the inner tube out and checked the rim tape - it was perfect - no signs of air bubbles or movement, and it appeared to be stuck down tight. Reinflated as tubeless and within a day it had deflated and the rim tape is a mess again.

I'm not sure that the rim tape has moved enough either time to be the cause of significant air leakage (hasn't come close to uncovering spoke holes, for example), but I don't understand why it moves at all as the tyre deflates...

I know that when I put sealant in to the tyres, this will be less of a problem BUT last year, one wheel stayed inflated for weeks and weeks and the other would deflate in about a week if I didn't pump it up regularly - and because the Schwalbes don't stay seated on the rim bead when they lose air, the sealant leaks everywhere if I don't remember to keep them pumped up.

Can anyone offer an explanation for why the rim tape moves as the tyre deflates, whether this issue is significant and what I can do to try to ensure that the problem wheel/tyre will produce a decent seal?

One more point - I swapped the tyres over to compensate for wear. Although I don't know for sure, I believe it's the tyre rather than the rim - the problem tyre does have a tiny nick (less than 0.5mm) at the very bottom edge of the bead, was wondering about using some sort of glue/filler just to make that edge perfect again, but this seems too small to have such a significant effect?

Would welcome your thoughts on this...
In my opinion, you are way over inflating. You're lucky they didn't blow off. Maybe that high a pressure is too much for the rim tape. Soap the tire beads if you are having trouble seating the tires. If you don't know where the leak is dunk the tire and rim in water and look for the bubbles.

alcatraz
Posts: 1337
Joined: Mon Aug 29, 2016 11:19 am

by alcatraz

If you submerge the wheel you could maybe get a clue to where it leaks.

What if the rim is simply too soft and flexes with the pressure.

Maybe you have a crack somewhere.

/a

jahknob
Posts: 118
Joined: Tue Sep 07, 2004 1:27 pm
Location: London, UK

by jahknob

Thanks to everyone to date for their thoughts and comments. I have an interesting update.

I have just put in new Milkit valves - they seem to be really good. Not sure about rim construction, but was doubtful that this would be the issue. And the Tesa tape seems to be at least as good as the Effetto Mariposa version - a bit stickier, so probably better in my book.. And I didn't really think that the wrinkling was allowing any air through the valve holes.

It has been bothering me that the tyres don't stay seated on the bead, but drop down when air pressure is low. However, I have ridden the wheels for a full season with no problems and, considering the level of difficulty that I have getting the tyres on and off the rim, I can't see them accidentally popping off.

I should really have thought of the simple test suggested by alcatraz - I did that and found that the tyres are bleeding air through the sidewalls! Lots of tiny bubbles all around on both sides of the tyre.. This does not seem right. The other tyre, bought at the same time is absolutely fine. I have drafted an email to Schwalbe for their comments and will let you know what they say.

j.

TobinHatesYou
Posts: 2037
Joined: Mon Jul 24, 2017 12:02 pm

by TobinHatesYou

Either you’re not taping your rims tight enough, or the tape you’re using has poor adhesion and a grippy non-sticky side. Use some other tape. A tire bead should not be able to pull the tape along with it.

Since someone mentioned they haven’t used Tesa, but always use Stan’s...well Stan’s is simply Tesa 4289. The tape I use is just generic 1” green powder coat masking tape from Amazon.com. Also please don’t inflate tubeless tires to 120-130psi ever. Fix the problem by using different tape and using sealant if you are having initial sealing issues.

Schwalbe tires use a porous inner casing called “MicroSkin” and it’s not meant to be completely air tight without the aid of sealant.

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IrrelevantD
Posts: 359
Joined: Sun Nov 29, 2015 5:47 pm
Location: Near DFW Airport

by IrrelevantD

jahknob wrote:
Sun Jun 17, 2018 8:08 pm
I should really have thought of the simple test suggested by alcatraz - I did that and found that the tyres are bleeding air through the sidewalls! Lots of tiny bubbles all around on both sides of the tyre.. This does not seem right. The other tyre, bought at the same time is absolutely fine. I have drafted an email to Schwalbe for their comments and will let you know what they say.
This is common on "Tubeless Ready" tires, I've had a few sets of tires, especially CX tires that do this. That being said, I've never seen it with Schwalbe Pro Ones, at least not with 23's or 25's. I just mounted up a brand new set of 25's a couple weeks ago and neither of them had any sidewall leakage. Their "micro skin" layer generally does a pretty good job of holding air.

Are you absolutely certain you have the Tubeless (or tubeless ready) version? If so, after injecting the sealant, hold the wheel with both hands, rotate it arround at least two rotations while shaking it latterlally vigorously. If this doesn't seal up the sidewalls, you may not be using enough sealant or may want to consider a different sealant.

I will echo what others have said about over inflating. That high a pressure with 28's, you could be risking damaging something. I realize you're only inflating that high to get the bead seated, and I'm asusming dropping the pressure after that, but it shouldn't take that high a pressure to get the bead seated. I would say just seating the bead, anything over 90-100psi would be excessive. I actually have rims that are only rated to 90psi with tubeless tires, I'd be scared to try to inflate tires to over 120 on them.
* There is a 70% chance that what you have just read has a peppering of cynicism or sarcasm and generally should not be taken seriously.
I'll leave it up to you to figure out the other 30%. If you are in any way offended, that's on you.

spdntrxi
Posts: 2029
Joined: Sat Jul 20, 2013 6:11 pm

by spdntrxi

my Schwalbe Pro Ones never leaked from the sidewall... they were very good at holding air with sealent..They were just a slight pain to mount and remove.

jfranci3
Posts: 368
Joined: Tue Jul 26, 2016 5:21 pm

by jfranci3

I have this happen on one of my tires. It was leaking out of the valve stem. The one tire had two o-rings on the valve, one on the inside and one on the outside. The other just had an inner ring on it. You might also have a piece of debris in the tire surface.


Try putting a balloon or bag over the valve stem overnight. Also try lying wheel on it's side for a few hours, flip and repeat for the other side.

TobinHatesYou
Posts: 2037
Joined: Mon Jul 24, 2017 12:02 pm

by TobinHatesYou

He said the tire was deflating overnight without sealant, which is not particularly surprising. Sometimes tires will hold air decently without sealant, sometimes there will be lots of gaps in the bead. Sometimes the area around the valve is the culprit.

MikeD
Posts: 151
Joined: Thu Dec 11, 2014 9:55 pm

by MikeD

jahknob wrote:Thanks to everyone to date for their thoughts and comments. I have an interesting update.

I have just put in new Milkit valves - they seem to be really good. Not sure about rim construction, but was doubtful that this would be the issue. And the Tesa tape seems to be at least as good as the Effetto Mariposa version - a bit stickier, so probably better in my book.. And I didn't really think that the wrinkling was allowing any air through the valve holes.

It has been bothering me that the tyres don't stay seated on the bead, but drop down when air pressure is low. However, I have ridden the wheels for a full season with no problems and, considering the level of difficulty that I have getting the tyres on and off the rim, I can't see them accidentally popping off.

I should really have thought of the simple test suggested by alcatraz - I did that and found that the tyres are bleeding air through the sidewalls! Lots of tiny bubbles all around on both sides of the tyre.. This does not seem right. The other tyre, bought at the same time is absolutely fine. I have drafted an email to Schwalbe for their comments and will let you know what they say.

j.
Find out where the leaks are through the sidewalls, turn the wheel so that sealant comes in contact with these areas. The leaks should seal. Pinhole leaks in tubeless ready tires are not uncommon. You need to get the sealant in contact with these areas.

TobinHatesYou
Posts: 2037
Joined: Mon Jul 24, 2017 12:02 pm

by TobinHatesYou

Rotate, shake, rotate, shake.

He still needs to fix his tape by using better tape and/or more tension.

by Weenie


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