To tubeless or not to tubeless

[Ben T]

You are probably right but your explanation doesn't account for the fact it is already in the stretched state when the puncture occurs.

[Brucey]

Ah, ok. So when you post this, so emphatically...

All it takes is the tyre to make a slightly better seal at the rim lip than at the tyre lip and there will soon be air pressure on all sides of  the tyre bead. When this happens the benefits of the hook  bead and the benefits of simple friction (except at the rim lip itself) are lost.

...it is based on absolutely no evidence whatsoever.

Right.

au contraire; that tyres blow off the rim in the way they sometimes do is quite suggestive. I have also seen numerous tubeless tyres on other vehicles where the tyre lip seal was lost but the air stayed in the tyre because the seal was made at the rim lip instead.   In many cases when the vehicle was used, the air would come out of the tyre faster than normal because lateral loads pulled the tyre away from the rim lip and let the air out.

 I'd ask you (or anyone else including tyre makers) to prove that tyres always continue to seal at the tyre lip as intended and/or to prove that the tyres are secure despite this.  I know very well the seal isn't always made where intended in other tubeless tyre designs and I know that the tyres/rims are engineered so that they are not very greatly adversely affected in this event.

  I am very far from convinced that bicycle tubeless systems always retain the seal where intended and that they tyres are proof by design against blowing off the rim when this occurs.

[zigzag]

could it be that the sealant makes a strong enough bond between the tyre and rim to prevent the bead from moving? we keep talking about this blowing off issue, that is so rare on a properly set up (i.e. not ghetto) system that it's hardly worth discussing. when the bead is snapped onto the "shelf" there is next to no chance (for recommended pressures) for it to pop over the rim hook as the bead is super-tight. even ghetto setups seem to work for many.

[rafletcher]

Certainly the latex based sealants "stick" the tyre to the rim bead. When I demounted some recently I need to break that seal - gentle thumb pressure - before the tyre would unseat.

[Hot Flatus]

Ah, ok. So when you post this, so emphatically...

All it takes is the tyre to make a slightly better seal at the rim lip than at the tyre lip and there will soon be air pressure on all sides of  the tyre bead. When this happens the benefits of the hook  bead and the benefits of simple friction (except at the rim lip itself) are lost.

...it is based on absolutely no evidence whatsoever.

Right.

au contraire; that tyres blow off the rim in the way they sometimes do is quite suggestive. I have also seen numerous tubeless tyres on other vehicles where the tyre lip seal was lost but the air stayed in the tyre because the seal was made at the rim lip instead.   In many cases when the vehicle was used, the air would come out of the tyre faster than normal because lateral loads pulled the tyre away from the rim lip and let the air out.

 I'd ask you (or anyone else including tyre makers) to prove that tyres always continue to seal at the tyre lip as intended and/or to prove that the tyres are secure despite this.  I know very well the seal isn't always made where intended in other tubeless tyre designs and I know that the tyres/rims are engineered so that they are not very greatly adversely affected in this event.

  I am very far from convinced that bicycle tubeless systems always retain the seal where intended and that they tyres are proof by design against blowing off the rim when this occurs.

I didn't ask you what you think you know (I know exactly what the answer will be, every time), I asked you for proof.

You then tried to turn it around and put the onus on me to prove that tyres seal where they should, but it isn't me making the assertion.

Then you cite tyres blowing off as evidence. 

Quite apart from none of us ever encountering a carefully mounted tubeless tyre blowing off (I'm sure you'll conjure up one of your supply of convenient "friends"), your logic is a bit silly. A is happening because of B. How do you know it is B? Because A.

[rafletcher]

I have also seen numerous tubeless tyres on other vehicles where the tyre lip seal was lost but the air stayed in the tyre because the seal was made at the rim lip instead. 

How can you know? How do you happen to be aware of so many many incidents of this type when no-oe else ever seems to have seen one - certainly not me.? Puzzling.

[Hot Flatus]

It is because Brucey is....

CLICK

[Peter]

I've really tried to tube less but every night finds me trawling down the right-hand side and listening to one great blues track after another.  Does the panel think there is any hope?

[Brucey]

I have also seen numerous tubeless tyres on other vehicles where the tyre lip seal was lost but the air stayed in the tyre because the seal was made at the rim lip instead. 

How can you know? How do you happen to be aware of so many many incidents of this type when no-oe else ever seems to have seen one - certainly not me.? Puzzling.

How many people have looked?    I have dealt with hundreds of tyres on other vehicles and I can only report what I have seen and know to be true.  When the tyre lip seal is lost (which in cars and motorcycles is often corrosion of the rim well BTW, and the corrosion in turn is caused by the rubbish that is used as to lubricate tyres when they are fitted) you can help the sealing out by using something between the rim lip and the tyre.  You can tell if the lip seal is lost by pushing the tyre away from the rim lip; bubbles in soapy water indicate that the lip seal in the well  isn't working any more, and if the air isn't coming out of the tyre it is only because the tyre is sealing against the rim lip instead.   

I see absolutely no reason why the same thing shouldn't happen with bicycle tubeless, only here the tyre may be reliant on the added friction/hooking (caused by a pressure differential across the tyre lip seal) to stay safely retained to the rim.

BTW it may be the case that sealant helps to retain tyres in some cases but
a) if the lip seal works as intended there shouldn't be much sealant between the tyre bead and the rim lip and
b) not all sealants work in the same way or cure in the same way to give a bond.
c) depending on the strength of the sealant as an adhesive, you still might be worse off with it than without it, if it creates a good seal near the rim lip, away from the tyre lip.


Car tyre beads contain a lb or two of steel and they need to; it is the only thing keeping the tyre on the rim.

Some years ago I discussed the issue of bicycle tubeless tyres with some others and the conclusion was that it was very likely that the beads in otherwise lightweight tyres would have to be a good deal stiffer/heavier if the tyres were to be properly secure.  This may yet turn out to be more the case than at present.

[Cudzoziemiec]

I've just noticed Brucey is no longer finishing each of his posts with "cheers." I'm not sure if that's a change specific to this thread, but perhaps it's a sign that it's time to make this thread a sticky. Preserve it as an example of YACF at its best and worst. A swamp of abuse, insults, misquotation, distortion and wilful misinterpretation of people's words, bullshit, opinions presented as fact, refusal to admit to gaps in one's knowledge, fabrication of facts, dismissal of direct experience, moral vanity, inability to comprehend that other people might want different things and refusal to agree that this is valid. And then more abuse, insults and bullshit.

And yet it also contains gems of technical insight and experience. And even the occasional calm and on-topic post. Presumably it's these that keep Quixotic Geek and others asking their questions here and finding the information they need.

[Brucey]

I am (as I mentioned upthread) pretty cheesed off with the attitude of some of the posters in this thread. A little scepticism is healthy enough but when it immediately turns into a tirade of ad hominem attacks and various other flavours of unrestrained  outright bullshit then this forum has IMHO got big problems.

BTW  there is a fundamental point which is also in danger of being overlooked. That is concerning what failure rate is acceptable in safety-critical parts?

Is it OK for one in ten to be faulty?: Obviously not.... but what about one in a hundred, one in a thousand or one in ten thousand? 

In things like motor cars even a very low failure rate is not tolerated and parts, cars etc are recalled. In structural parts like forks on bikes the same thing happens (but sadly it usually takes someone being serious injured or even dying before the recall is done, even though the manufacturers/suppliers are usually abundantly aware of the problem well before then). Parts that are considered so dangerous that they are no longer to be sold are often in use by a vast majority of folks who would say 'I have had no problems with them'.

My point is that any one person's positive experience with a product counts for very little when trying to prove that a product is really safe. You could (say) have 999 people saying that 'it is OK' yet the product might kill or seriously injure the thousandth and it is all set for a recall (or should be). Obviously if you know about the failures and have some idea why they might have occurred you won't be using the product.

Despite this there have been various attempts to confine discussion only to those who are happily using the product. Some discussion that is; potentially 999 of the blissfully ignorant and one person in hospital or a morgue...

My take on road tubeless is that at best, it may spare you the inconvenience of some punctures, especially if you choose to run tyres that are not best suited to the conditions.  However when you do have problems, they are likely to be appreciably worse to deal with than a typical tubed tyre.   At worst, road tubeless is potentially a load of half-baked rubbish that shows signs of being inherently problematic and/or intrinsically unsafe, and until there is a proper standard for it in place, you are reliant on the whims of  manufacturers (esp tyre manufacturers with a pretty flakey past record for consistency and quality) for any semblance of real safety. Worse yet, it is doubtful that any simple test you can do will prove that a given tyre/rim combination is really safe or not, or will stay that way in service.

[grams]

You’re still talking as if road tubeless is a hypothetical idea that no one’s tried in the real world yet. When I was shopping for my last new bike 2+ years ago it was a mainstream technology then! At some point you have to accept that it’s a real thing that *works* with the normal range of pros and cons of any technology, and that it’s not going to kill anyone.

The dearth of dissent seems to be because there are very few people (certainly on YACF, and perhaps in general)  who’ve given tubeless a serious go and hated it enough to recommend others don’t even try it. That should tell you something.

[sojournermike]

I've just noticed Brucey is no longer finishing each of his posts with "cheers." I'm not sure if that's a change specific to this thread, but perhaps it's a sign that it's time to make this thread a sticky. Preserve it as an example of YACF at its best and worst. A swamp of abuse, insults, misquotation, distortion and wilful misinterpretation of people's words, bullshit, opinions presented as fact, refusal to admit to gaps in one's knowledge, fabrication of facts, dismissal of direct experience, moral vanity, inability to comprehend that other people might want different things and refusal to agree that this is valid. And then more abuse, insults and bullshit.

And yet it also contains gems of technical insight and experience. And even the occasional calm and on-topic post. Presumably it's these that keep Quixotic Geek and others asking their questions here and finding the information they need.

Yes, this is very true. Shame about the nonsense really, even though it has brought forth some interesting discussion.

[sojournermike]

what failure rate is acceptable in safety-critical parts?

Is it OK for one in ten to be faulty?: Obviously not.... but what about one in a hundred, one in a thousand or one in ten thousand? 

In things like motor cars even a very low failure rate is not tolerated and parts, cars etc are recalled. In structural parts like forks on bikes the same thing happens (but sadly it usually takes someone being serious injured or even dying before the recall is done, even though the manufacturers/suppliers are usually abundantly aware of the problem well before then). Parts that are considered so dangerous that they are no longer to be sold are often in use by a vast majority of folks who would say 'I have had no problems with them'.

This is fundamental of course. A key element here is that the parts should be safe by design  and that any failures should be the consequence of faults, which should then be eliminated through manufacture (primarily) and QC (as a check on manufacture). This is basic six sigma stuff really.

I don't think any of us here have the information to actually know about tubeless failure rates in everyday correct useage. Please correct me if I am wrong - certainly that is possible.  That would be more enlightening and helpful, particularly if there was also an analysis of failure modes. (not criticising Brucey's input, but something bigger and statistically valid)

Brucey flags tyre retention issues worth thinking through. Certainly, we expect, and rely on, the manufacturers to have done so and to have found reliable and manufacturable solutions to the challenges. Much the same as the history of the tubed clincher.

The biggest fear is the one raised by Brucey in his comment about the 'culture' of the industry and the well known failures of structural components such as forks. None of us want to be involved in a potentially serious accident as a consequence of poor development, manufacturing or quality management by a corporation that should 'know better'.

Mike

[Hot Flatus]

That's the thing about tubeless failures. We will never know.

The dead don't speak.

[sojournermike]

That's the thing about tubeless failures. We will never know.

The dead don't speak.

Inquests and post accident analysis do though.

However, I haven't heard any and my only experience of spontaneous demounts involved tube type tyres - once with a presumably poorly installed tube and once experimenting with over inflation in ghetto tubeless mode...

[LittleWheelsandBig]

Brucey may have picked up a failure mechanism that is only rarely seen. It might be similar to disc braked QR front wheels loosening and self-ejecting from fork dropouts. That failure mechanism was rarely seen and misunderstood when it did happen for a long time before it became orthodoxy. Alternatively, it might be nothing at all.

I simply don't have enough knowledge on this subject to say anything sensible, so I'm just watching from the sidelines. So far, I've not found a basic fallacy in his logic.

[Si S]

My only bad experience of tubeless over 12k km is a front wheel blow out at moderately high speed in the peak district, this was entirely my own fault as I knew the temporary repair I'd made few days prior using two anchovies was not up to the job but rode it anyway, which is the second time I've blown a front tyre while descending due to laziness. The tyre stayed mounted on the rim somewhat fortunately and has since been repaired properly.

No matter what manufacturers do, irrespective of the tech, there will always be one idiot.

[sojournermike]

Brucey may have picked up a failure mechanism that is only rarely seen. It might be similar to disc braked QR front wheels loosening and self-ejecting from fork dropouts. That failure mechanism was rarely seen and misunderstood when it did happen for a long time before it became orthodoxy. Alternatively, it might be nothing at all.

I simply don't have enough knowledge on this subject to say anything sensible, so I'm just watching from the sidelines. So far, I've not found a basic fallacy in his logic.

Agree, the logic is sound and the test is whether the manufacturers have developed a reliable solution.

If the failure rate is 1% we'd see it all over, but if it's only 1 in 1m then it's much harder to observe. In either case, none of us want to be the one.

[Hot Flatus]

It is a hypothesis. Nothing else.

As others have said, if losing a tubeless tyre was common we would hear about it. But we don't. Which means that Brucey's page upon page of warning of 'potential' occurrences are largely pointless and of no use. If anything they detract from real safety issues with tubed tyres, such as blowouts, which could be mitigated by going tubeless, and which may well be more likely to occur.

[Brucey]

I would love to see some statistics too.  Sorting the wheat from the chaff won't be easy (folk will do daft things and one thing this thread has demonstrated is that it isn't always easy to reach agreement even when tubes burst - which leaves physical evidence- let alone with tubeless).

But one thing that struck me quite vividly was that in the OPTB blog, at least half the comments were posted in about twelve hours, and many of the posts reported that they had experienced tubeless tyres blowing off the rim, (fortunately mainly when not actually riding the bike).  To me this suggests that perhaps the blog has a much wider readership than I'd imagined and/or tyres blowing off rims is more common than you might expect.  Nothing is so proven of course, except perhaps that if you want the failure rate to be less than 1 in a million (regardless of cause) then lots and lots of tyres would have to have been sold....

BTW I just noticed that one poster in those comments has seen the exact same thing as I mentioned in relation to other tubeless systems; you can often tell that the tyre lip seal has failed by pushing the tyre away from the rim lip, and seeing leakage. Despite the presence of sealant, he reports seeing air and sealant escape from his tubeless setup (which 'he no longer trusts') when he does this.  Unfortunately I don't think this is an infallible test for a failed tyre lip seal, i.e. I don't think you can definitely prove that you don't have a problem this way.

[sojournermike]

Nothing is so proven of course, except perhaps that if you want the failure rate to be less than 1 in a million (regardless of cause) then lots and lots of tyres would have to have been sold....

Being pedantic, for fun and not criticism, I think that you'd need to sell a lot of tyres to know the failure rate was below 1 in 1m:)

[rogerzilla]

I've just noticed Brucey is no longer finishing each of his posts with "cheers." I'm not sure if that's a change specific to this thread, but perhaps it's a sign that it's time to make this thread a sticky. Preserve it as an example of YACF at its best and worst. A swamp of abuse, insults, misquotation, distortion and wilful misinterpretation of people's words, bullshit, opinions presented as fact, refusal to admit to gaps in one's knowledge, fabrication of facts, dismissal of direct experience, moral vanity, inability to comprehend that other people might want different things and refusal to agree that this is valid. And then more abuse, insults and bullshit.

And yet it also contains gems of technical insight and experience. And even the occasional calm and on-topic post. Presumably it's these that keep Quixotic Geek and others asking their questions here and finding the information they need.

I will add that one of our original members has filed for account deletion, possibly because of some of the vitriol in this thread, in which he/she was a participant.  I've only read two pages and it is pretty depressing stuff.

[sojournermike]

I've just noticed Brucey is no longer finishing each of his posts with "cheers." I'm not sure if that's a change specific to this thread, but perhaps it's a sign that it's time to make this thread a sticky. Preserve it as an example of YACF at its best and worst. A swamp of abuse, insults, misquotation, distortion and wilful misinterpretation of people's words, bullshit, opinions presented as fact, refusal to admit to gaps in one's knowledge, fabrication of facts, dismissal of direct experience, moral vanity, inability to comprehend that other people might want different things and refusal to agree that this is valid. And then more abuse, insults and bullshit.

And yet it also contains gems of technical insight and experience. And even the occasional calm and on-topic post. Presumably it's these that keep Quixotic Geek and others asking their questions here and finding the information they need.

I will add that one of our original members has filed for account deletion, possibly because of some of the vitriol in this thread, in which he/she was a participant.  I've only read two pages and it is pretty depressing stuff.

That’s really sad. Hopefully they will reconsider and perhaps the thread should be deleted or moved somewhere less public as a warning.

[vorsprung]

Let's not be depressed about account deletion.  Most people use Facebook now because their aunt is on it

Tubeless is fabulous but it doesn't quite work the same way as clinchers.  But mostly it is ok

People still spend vast sums on titanium frames and they are often prone to failure.  Mostly they are ok

Brucey is just discussing the situation and we all respect his opinion