Author Topic: Tubeless for Dummies  (Read 194291 times)

Re: Tubeless for Dummies
« Reply #125 on: 01 October, 2015, 12:56:36 pm »
Having been putting off (and off, and off ...) actually switching over, can anyone tell me how large the 28mm Schwalbe Ones come up? Currently trying to work out whether they'll fit in place of Krylion 25s with reasonable clearance.

On my Archetype rims (23mm wide external) they come up as 27mm tall and about 29.5mm wide

EDIT
Just re-measured at max pressure (6.5 bar)
28 mm tall, 31 mm wide

Re: Tubeless for Dummies
« Reply #126 on: 03 October, 2015, 11:30:11 pm »
Thanks for that^.

Still need to actually measure clearances myself, then try to extrapolate to narrower rims - but at least I have some figures.

bikey-mikey

  • AUK 6372
  • Yes, I am completely mad ! a.k.a. 333
Re: Tubeless for Dummies
« Reply #127 on: 04 October, 2015, 11:48:03 pm »
A short tale to illustrate a maintenance issue...

Two days ago I felt my rear tyre begin to get 'squirrelly', meaning pressure reduced. I stopped and it was quite a bit down, and I found a tiny hole in the sidewall, bubbling but not sealing. I put my finger on it and gave it ten seconds, and it was sealed. I pumped tyre up to nearly the pressure I usually use, and finished the ride. It cost me four minutes....

Having lent my bottle of sealant to my local bike shop, I took the bike there the next day, with my "putting extra fluid in" syringe, and I showed them the tiny hole (now sealed solid) and suggested that the tyre was probably just about empty of sealant fluid, which would account for the delayed seal and loss of significant pressure.

Nigel the owner agreed and showed me an easy way to test. First you unscrew the valve core, with the valve situated a 3 o'clock, so any fluid will have drained away and not spurt all over the place.  Then you put the valve at the bottom.  Then you get a tiny Allen key and dip it to the inside bottom of the tyre, withdraw it, and read off the level of the fluid.

My tyre had none.....

We reposed it, and you then have to reinflate / reseat the tyre...

I did a 200 today with no issues.

The moral of the story is that I was lucky, cos if there had not been the last dregs of fluid in the tyre, it would not have sealed, and I would have had to put in a tube, which would have taken much longer.

The tyre had done maybe three months and 7,000 kms and the fluid was just about gone...

I strongly suggest you check your sealant regularly.
I’ve decided I’m not old. I’m 25 .....plus shipping and handling.

Cycling heatmap
https://www.strava.com/athletes/4628735/heatmaps/6ed5ab12#10/51.12782/-3.16388

Re: Tubeless for Dummies
« Reply #128 on: 05 October, 2015, 02:11:04 am »
Nigel the owner agreed and showed me an easy way to test. First you unscrew the valve core, with the valve situated a 3 o'clock, so any fluid will have drained away and not spurt all over the place.  Then you put the valve at the bottom.  Then you get a tiny Allen key and dip it to the inside bottom of the tyre, withdraw it, and read off the level of the fluid.

I strongly suggest you check your sealant regularly.

I've often wondered about this.  That's a fine and dandy idea.  What measurement level on the Allen Key would be considered a suitable amount of sealant?


Re: Tubeless for Dummies
« Reply #129 on: 05 October, 2015, 12:19:07 pm »
A short tale to illustrate a maintenance issue...

Two days ago I felt my rear tyre begin to get 'squirrelly', meaning pressure reduced. I stopped and it was quite a bit down, and I found a tiny hole in the sidewall, bubbling but not sealing. I put my finger on it and gave it ten seconds, and it was sealed. I pumped tyre up to nearly the pressure I usually use, and finished the ride. It cost me four minutes....

Having lent my bottle of sealant to my local bike shop, I took the bike there the next day, with my "putting extra fluid in" syringe, and I showed them the tiny hole (now sealed solid) and suggested that the tyre was probably just about empty of sealant fluid, which would account for the delayed seal and loss of significant pressure.

Nigel the owner agreed and showed me an easy way to test. First you unscrew the valve core, with the valve situated a 3 o'clock, so any fluid will have drained away and not spurt all over the place.  Then you put the valve at the bottom.  Then you get a tiny Allen key and dip it to the inside bottom of the tyre, withdraw it, and read off the level of the fluid.

My tyre had none.....

We reposed it, and you then have to reinflate / reseat the tyre...

I did a 200 today with no issues.

The moral of the story is that I was lucky, cos if there had not been the last dregs of fluid in the tyre, it would not have sealed, and I would have had to put in a tube, which would have taken much longer.

The tyre had done maybe three months and 7,000 kms and the fluid was just about gone...

I strongly suggest you check your sealant regularly.

But where had it gone ????

Did it blow out of the tiny hole and fly off the tyre to land on the inside of the mudguard? It shouldn't have if the bike was rolling along. It would have been thrown to the outer extremity of the inside of the tyre and stayed there.

Re: Tubeless for Dummies
« Reply #130 on: 05 October, 2015, 12:58:34 pm »
Every time there is a puncture a bit leaks out, a bit seals the hole. So it will get used up over time.
<i>Marmite slave</i>

Re: Tubeless for Dummies
« Reply #131 on: 05 October, 2015, 01:24:55 pm »
I recently had a very significant visitation on mine which took quite some time to seal.... but seal it did, after liberally coating the inside of the mudguard, the derailleur, the chain stays etc etc.
I was left with about 10 psi - but it held when I pumped up to about 80 psi... and stayed sealed long enough to get home, and a few rides more.

I later dismounted  the tyre, more to check for any significant damage than to see how little sealant was left.   

Good trick with the allen key, must do a dip test before I go out next to establish a baseline.

Man of the Mountains

  • Just a ridin' on my chrome horse
Re: Tubeless for Dummies
« Reply #132 on: 05 October, 2015, 08:48:00 pm »
Latex sealant is water based and the water vapour diffuses through the rubber (in the same way that air does causing a loss in pressure only water molecules are smaller than O2 and N2). That is why you are left with the dry stringy latex residue.
Question everything, believe nothing.

bikey-mikey

  • AUK 6372
  • Yes, I am completely mad ! a.k.a. 333
Re: Tubeless for Dummies
« Reply #133 on: 05 October, 2015, 10:21:54 pm »
Also whenever you pump up the tyre there is movement of high pressure air in and out of the pump, and that would also entail movement both ways through the valve stem, whilst the pump is connected..

When you disconnect the pump there is always a 'pssssssst' as the higher pressure air inside the pump escapes..

And inevitably it will contain some volatilised sealant...


Any physicists care to confirm my conjecture?? Please ?
I’ve decided I’m not old. I’m 25 .....plus shipping and handling.

Cycling heatmap
https://www.strava.com/athletes/4628735/heatmaps/6ed5ab12#10/51.12782/-3.16388

Phil W

Re: Tubeless for Dummies
« Reply #134 on: 05 October, 2015, 11:07:40 pm »
Yes, topping up roughly every 3 months is about right. I don't bother with any Allen key checks. Just dismount the bead, look visually, top up, reseat and inflate. It does last longer in Winter mind as you'd expect.

Man of the Mountains

  • Just a ridin' on my chrome horse
Re: Tubeless for Dummies
« Reply #135 on: 05 October, 2015, 11:35:24 pm »
The valve only opens when air is rushing in i.e. when the external pressure is higher than the internal, so only a tiny amount of vapour could escape during top ups. A curious property of Nitrogen is that despite being less dense than Oxygen it is also less permeable through rubber. This means that the proportion of Nitrogen increases with each top up (Oxygen and water vapour having leaked out more). Some people pay to have their car tyres filled with Nitrogen because, well because its made from snake oil. We get the same effect for free ;-)

3 months works on my 29er but I prefer to avoid unseating the bead lest that introduces foreign matter to the established seal.
Question everything, believe nothing.

Re: Tubeless for Dummies
« Reply #136 on: 06 October, 2015, 12:10:33 am »
Having been putting off (and off, and off ...) actually switching over, can anyone tell me how large the 28mm Schwalbe Ones come up? Currently trying to work out whether they'll fit in place of Krylion 25s with reasonable clearance.

A bit late back to this thread, but 28c Schwalbe One's measure up at 30mm wide on Pacenti SL23's - internal width 18.5mm. Can't wait to see how wide they are on Kinlin XR31T (19mm internal)

Mike

Re: Tubeless for Dummies
« Reply #137 on: 06 October, 2015, 02:07:35 am »
Thanks - another datapoint, and delightfully consistent with Somnolent's.

Ben T

Re: Tubeless for Dummies
« Reply #138 on: 06 October, 2015, 08:32:47 am »
I recall a 25mm schwalbe one measures exactly 26mm wide while a 25mm Hutchinson measures exactly 24mm.

Re: Tubeless for Dummies
« Reply #139 on: 06 October, 2015, 08:48:51 am »
I recently had a very significant visitation on mine

So did I, yesterday - but mine didn't seal  :(  Mind you there was an 8mm sabre shaped piece of metal swarf right through the carcass!  Luckily I was <200m from starting out. In this instance I just intubated the tyre (I'm on hols at a friends place in France) and I'll sort it properly when I get home.
We are making a New World (Paul Nash, 1918)

T42

  • Apprentice geezer
Re: Tubeless for Dummies
« Reply #140 on: 06 October, 2015, 09:46:59 am »
I recently had a very significant visitation on mine

So did I, yesterday - but mine didn't seal  :(  Mind you there was an 8mm sabre shaped piece of metal swarf right through the carcass!  Luckily I was <200m from starting out. In this instance I just intubated the tyre (I'm on hols at a friends place in France) and I'll sort it properly when I get home.

What happens then? Does the tube get cemented to the inside of the tyre with residual fluid?
I've dusted off all those old bottles and set them up straight

Re: Tubeless for Dummies
« Reply #141 on: 06 October, 2015, 02:24:44 pm »
Also whenever you pump up the tyre there is movement of high pressure air in and out of the pump, and that would also entail movement both ways through the valve stem, whilst the pump is connected..

When you disconnect the pump there is always a 'pssssssst' as the higher pressure air inside the pump escapes..

And inevitably it will contain some volatilised sealant...


Any physicists care to confirm my conjecture?? Please ?

Connect the Trackpump head to the presta and there is a clear passage of pressure to the gauge on the pump. Air from inside the tyre rushes to pressurise the pump's connection hose and gauge. This may allow sealant to get into the pump's connection hose. Then there is a valve between the gauge and the outlet of the pump cylinder.

My opinion is that sealant will eventaually get to the gauge. Might take a long time. Dunno if the gauge can be internally cleaned.

On disconecting the pump head from the presta, the 'trapped volume' in the gauge, connector hose and pump head releases with a quick 'pssst'.

Re: Tubeless for Dummies
« Reply #142 on: 08 October, 2015, 01:30:06 am »
Also whenever you pump up the tyre there is movement of high pressure air in and out of the pump, and that would also entail movement both ways through the valve stem, whilst the pump is connected..

When you disconnect the pump there is always a 'pssssssst' as the higher pressure air inside the pump escapes..

And inevitably it will contain some volatilised sealant...


Any physicists care to confirm my conjecture?? Please ?

Connect the Trackpump head to the presta and there is a clear passage of pressure to the gauge on the pump. Air from inside the tyre rushes to pressurise the pump's connection hose and gauge. This may allow sealant to get into the pump's connection hose. Then there is a valve between the gauge and the outlet of the pump cylinder.

Your pump works very differently to mine, and indeed to any I have ever used.

With mine, I connect the pump head to the valve, and there is no movement of air in either direction because the valve remains closed. When I pump, the pressure rises rapidly in the gauge, hose and head rises rapidly, until it exceeds the pressure inside the tyre/tube sufficiently to press open the valve. Then, air from the pump rushes into the tyre, and when the pressure equalises, the valve closes. Pump again,  and restart the cycle, with air moving from pump to tyre.

bikey-mikey

  • AUK 6372
  • Yes, I am completely mad ! a.k.a. 333
Re: Tubeless for Dummies
« Reply #143 on: 08 October, 2015, 05:20:05 pm »
Also whenever you pump up the tyre there is movement of high pressure air in and out of the pump, and that would also entail movement both ways through the valve stem, whilst the pump is connected..

When you disconnect the pump there is always a 'pssssssst' as the higher pressure air inside the pump escapes..

And inevitably it will contain some volatilised sealant...


Any physicists care to confirm my conjecture?? Please ?

Connect the Trackpump head to the presta and there is a clear passage of pressure to the gauge on the pump. Air from inside the tyre rushes to pressurise the pump's connection hose and gauge. This may allow sealant to get into the pump's connection hose. Then there is a valve between the gauge and the outlet of the pump cylinder.

Your pump works very differently to mine, and indeed to any I have ever used.

With mine, I connect the pump head to the valve, and there is no movement of air in either direction because the valve remains closed. When I pump, the pressure rises rapidly in the gauge, hose and head rises rapidly, until it exceeds the pressure inside the tyre/tube sufficiently to press open the valve. Then, air from the pump rushes into the tyre, and when the pressure equalises, the valve closes. Pump again,  and restart the cycle, with air moving from pump to tyre.

I agree that as you pump, the pressure in the pump rises, and then the valve opens and as you continue the pump stroke the pressure rises equally in the entire tyre and pump system, and the valve remains open, however as you reverse the pump handle the pump undergoes a partial vacuum, which then sucks fresh air into the pump from the outside world, but that partial vacuum also sucks air back from the tyre, and as the tyre is at a higher pressure than the outside world, air from the tyre comes faster, and at this point I'm back to agreeing that this reverse rush of air, as it flows past the valve, begins the process of closing the valve, and after the valve is fully closed there could thereafter be no further leakage....

but I still might be wrong....  ;D
I’ve decided I’m not old. I’m 25 .....plus shipping and handling.

Cycling heatmap
https://www.strava.com/athletes/4628735/heatmaps/6ed5ab12#10/51.12782/-3.16388

Kim

  • Timelord
    • Fediverse
Re: Tubeless for Dummies
« Reply #144 on: 08 October, 2015, 11:47:41 pm »
I've got a pump where either the pressure rises in the tube and opens the tyre valve, or the chuck holds the tyre valve open and pressurises the tube/gauge to the tyre's pressure from the outset - depending on how firmly you attach the head.

Ben T

Re: Tubeless for Dummies
« Reply #145 on: 10 October, 2015, 04:17:14 pm »
Connect the Trackpump head to the presta and there is a clear passage of pressure to the gauge on the pump. Air from inside the tyre rushes to pressurise the pump's connection hose and gauge. This may allow sealant to get into the pump's connection hose. Then there is a valve between the gauge and the outlet of the pump cylinder.

My opinion is that sealant will eventaually get to the gauge. Might take a long time. Dunno if the gauge can be internally cleaned.

On disconecting the pump head from the presta, the 'trapped volume' in the gauge, connector hose and pump head releases with a quick 'pssst'.

I think this is complete bollocks, because this fails to account for the fact that the sealant is not uniformly distributed around the tyre, but it 'pools' at the bottom, so unless you connect the pump with the valve at the bottom which you wouldn't, then there will be hardly any flow of sealant into the pump.
I think even if it does, the pump will fail for other reasons long before it fails due to the backdraft of sealant contaminating the guage.

Re: Tubeless for Dummies
« Reply #146 on: 10 October, 2015, 05:33:04 pm »
That's probably a fair summary.  Tubeless with sealant has been out for, what, 10 years?  We're not hearing loads of mountain bikers reporting that their pumps have seized up!

Re: Tubeless for Dummies
« Reply #147 on: 10 October, 2015, 05:39:25 pm »
unless you connect the pump with the valve at the bottom which you wouldn't,

I generally do, because it helps to avoid symptoms akin to

I've got a pump where either the pressure rises in the tube and opens the tyre valve, or the chuck holds the tyre valve open and pressurises the tube/gauge to the tyre's pressure from the outset - depending on how firmly you attach the head.

On the other hand,

I think this is complete bollocks,

seems fair.


Re: Tubeless for Dummies
« Reply #148 on: 10 October, 2015, 07:07:49 pm »
unless you connect the pump with the valve at the bottom which you wouldn't,

And even if you did the valve is at the top of the bottom, and the sealant will have pooled to the bottom of the bottom.

Re: Tubeless for Dummies
« Reply #149 on: 11 October, 2015, 10:08:40 pm »
unless you connect the pump with the valve at the bottom which you wouldn't,

And even if you did the valve is at the top of the bottom, and the sealant will have pooled to the bottom of the bottom.
But what if you are in Australia, eh? What then?
<i>Marmite slave</i>