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Old 09-21-05, 11:42 AM   #1
yotool
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Filling Road Tubes w/ Silicone

Anybody have any thoughts on my filling my 700x25/28 road tubes with just a bit of pure silicone lubricant to "seal the pores" of the tube's Butyl rubber. This would be in an attempt to not have to fill my tires before EVERY ride to keep them @ 90psi. I currently lose about 1 or so psi per day in these skinny puppies even with new tubes. I would like to not beat on the lil' Presta valve so frequently.

I got this idea from the refrigeration industry where they found that the "mineral" oil used for the older R-12 systems actually had a side-effect of sealing the porous rubber refrigeration lines of an automobile A/C system so that they can then be converted for use of the newer R-134a refrigerant which has a smaller molecule size and would normally require the use of new "barrier" hose to keep them from leaking.

The choice of pure silicone would be due to the fact that it is totally compatible with Butyl rubber as Butyl rubber is not suggested for use with petroleum-based lubes. I don't like SLIME as it is much heavier and has a documented and limited life.

The only down-side I would anticipate would be when a puncture happens one would have to remove the silicone that might escape but it would seem that a bit of rubber glue could be used to remove this small leakage from the puncture site prior to actually using more of the same glue for the final patch application.

I am testing this method now...
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Old 09-21-05, 12:22 PM   #2
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Sounds like and interesting experiment; please post the results.

Jason
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Old 09-21-05, 01:08 PM   #3
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1 psi/day! That's really good.

The tubes on on of my bikes lose about 30-40 psi after just a fwe hours. And no, I don't have a leak.

Are you talking about silicone caulk, like on bathtubs, or something else?

Why don't you just over-inflate your tires, and when the pressure drops it will be just right!
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Old 09-21-05, 02:08 PM   #4
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Originally Posted by BostonFixed
1 psi/day! That's really good.

The tubes on on of my bikes lose about 30-40 psi after just a fwe hours. And no, I don't have a leak.

Are you talking about silicone caulk, like on bathtubs, or something else?

Why don't you just over-inflate your tires, and when the pressure drops it will be just right!
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30-40 psi after a few hours cannot be right. Put those puppies underwater and find that leak!!!

About the silicone, no not Silicone-based RTV sealant. RTV would not evenly distribute throughout the inside of the tube walls, and would eventually "set-up" [cure] improperly and take your tires out of balance, not to mention being pretty difficult to get into that little Presta valve also. I am talking about "pure silicone" [oil] lubricant, without any "carrier solvents" either. I have some from a copy machine repair kit that is pure silicone lubricant...
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Old 09-21-05, 02:15 PM   #5
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hey i've heard of ppl, and some friends of mine who have filled up their tires with this green tire tube sealing stuff that you're supposed to just put onto a leak to seal it up, but they fill the entire tube with it and no air (i think). I'm not sure if it can work with a presta valve or not, but maybe. They say doing this will pretty much ensure that u never get a punctured tire ever again.
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Old 09-21-05, 02:27 PM   #6
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Originally Posted by MrSlappy
hey i've heard of ppl, and some friends of mine who have filled up their tires with this green tire tube sealing stuff that you're supposed to just put onto a leak to seal it up, but they fill the entire tube with it and no air (i think). I'm not sure if it can work with a presta valve or not, but maybe. They say doing this will pretty much ensure that u never get a punctured tire ever again.

That would probably be the "Slime" I was not talking about.

Also "Slime" is not pressurized and would not work like you are saying [i.e replace the air under pressure entirely]. We are talking 87-120+ psi equivalent tire pressure "hardness" here...

They do make "airless" solid rubber tires, but it seems that the jury is still out on them....
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Old 09-21-05, 02:38 PM   #7
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Quote:
Originally Posted by yotool
That would probably be the "Slime" I was not talking about.

Also "Slime" is not pressurized and would not work like you are saying [i.e replace the air under pressure entirely]. We are talking 87-120+ psi equivalent tire pressure "hardness" here...

They do make "airless" solid rubber tires, but it seems that the jury is still out on them....

Do you have a syringe that will fit over the valve? Just wondering about your delivery method.
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Old 09-21-05, 03:35 PM   #8
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Originally Posted by ofofhy
Do you have a syringe that will fit over the valve? Just wondering about your delivery method.
Given the Presta valve and its air port is so small, I just:

1) Deflated the tire(s)
2) took the hose off of my Performance brand Hurricane floor pump (@ the pump end) to allow the silicone to displace the air in the head/hose as the silicone is relatively viscous
3) took the innards out of of the "head" of hose [the stuff that lets you switch between Presta and Schraeder]
4) filled the head and, indirectly, some of the hose with a "seemingly appropriate" amount of silicone
5) put the hose back on the pump
6) made sure the tire's Presta valve was @ the bottom of the wheel (so gravity can assist as opposed to hinder the flow of silicone)
7) hooked the pump up to the Presta valve nice and tight to avoid a leak of silicone (and of course air)
6) filled the tire back up essentially pushing the silicone in along w/ the air.

Seemed to work OK.

Last edited by yotool; 09-21-05 at 03:44 PM.
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Old 09-21-05, 04:00 PM   #9
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Quote:
Originally Posted by yotool
They do make "airless" solid rubber tires, but it seems that the jury is still out on them....
sidney might have an opinion about these. I think I remember reading that these were rubbish.
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Old 09-21-05, 05:01 PM   #10
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In my years of involvement with precision or performance lubricants, no lube to my experience has ever fixed a mechanical problem - so find and repair the leak !

Silicone lubricant in an aerosol spray I assume? Well, this is a very fine molecular lubricant, ..... as in LUBRICANT.

There would be no "adhesion" or "solidifying" or "tackifying" or "coagulating" properties that would act as sealant. Also, unless you were using a USDA-H1 or Agriculture Canada Approved Food Grade Quality Silicone you may get very serious problems with the "carrier" of the Silicone and its possible affects on the rubber parts of the wheel, especially if the carrier is a petroleum derivative, which is usually a volatile solvent.

You may also destabilize your wheel integrity and its adhesion characteristics with the wheel and road under torque load, forward, twisting or stopping.

Good luck !

Stv

PS. Are you speculating that the silicone will "swell" around the leak, thus closing as in healing itself?

Last edited by Stv; 09-21-05 at 05:37 PM.
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Old 09-21-05, 05:05 PM   #11
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Quote:
Originally Posted by yotool
They do make "airless" solid rubber tires, but it seems that the jury is still out on them....
For whatever it's worth, Sheldon Brown has a rather low opinion of airless tires.
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Old 09-21-05, 05:18 PM   #12
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Quote:
Originally Posted by yotool
The only down-side I would anticipate would be when a puncture happens one would have to remove the silicone that might escape but it would seem that a bit of rubber glue could be used to remove this small leakage from the puncture site prior to actually using more of the same glue for the final patch application.

I am testing this method now...
Escaped silicone would render the vulcanising glue useless, that might be more of a serious problem. You could try the glue issue on and old tube, spray with silicone, see if it can be effectively removed.
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Old 09-21-05, 07:03 PM   #13
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Quote:
Originally Posted by Stv
In my years of involvement with precision or performance lubricants, no lube to my experience has ever fixed a mechanical problem - so find and repair the leak !

Silicone lubricant in an aerosol spray I assume? Well, this is a very fine molecular lubricant, ..... as in LUBRICANT.

There would be no "adhesion" or "solidifying" or "tackifying" or "coagulating" properties that would act as sealant. Also, unless you were using a USDA-H1 or Agriculture Canada Approved Food Grade Quality Silicone you may get very serious problems with the "carrier" of the Silicone and its possible affects on the rubber parts of the wheel, especially if the carrier is a petroleum derivative, which is usually a volatile solvent.

You may also destabilize your wheel integrity and its adhesion characteristics with the wheel and road under torque load, forward, twisting or stopping.

Good luck !

Stv

PS. Are you speculating that the silicone will "swell" around the leak, thus closing as in healing itself?

I think you missed some key points that I already addressed in the initial proposal:
  1. The reason for the proposal was to SLOW the loss of tire pressure caused by the fact that all rubber tubes (and even non-defective car tires etc.) new or old ones leak air at a slow rate that is determined by the relative porosity of the rubber and the size of the (in this case) air molecule as well as by the relative pressure difference between the inside of the tube and the outside. It was not to STOP a leak caused by some form of outright 'puncture'. This puncture scenario is the SLIME dilio. I am specifically NOT talking 'bout that issue. The proposal would assume that the silicone would 'plug" the gaps in the butyl rubber tube which are always allowing air to escape.
  2. I did specifically address the use or PURE silicone lubricant with no "solvent-containing carrier".
  3. I am not talking about a half-gallon of silicone per tube, and even if the tube did puncture, your destablization or "loss of control" would happen as a direct result of a deflated or under-inflated tire not the silicone (most of which would still be between the tube and the INSIDE wall of the tire).

Last edited by yotool; 09-21-05 at 07:17 PM.
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Old 09-21-05, 07:20 PM   #14
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If the silicone can penetrate the tube what's it going to do to the sticky stuff that holds your rim tape in place?
My first thought was how will the silicone coat the entire tube? Seems it would centrifuge to the tread side.
I don't have any problem pumping my tires up every day. Still it sounds like an interesting experiment and I'd like to hear how it turns out.

Al
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Old 09-21-05, 07:22 PM   #15
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1/-Silicone is inert. It will have no reaction itself with the tube. Is air bleed from the valve or the porous tube material. Either way, the Silicone molecule will not have any effect, it is a lubricant.

2/-Have you attempted to source, let alone price a "pure" silicone?

3/-A little silicone goes a long way. Several years ago, I worked with a FORD assembly paint plant that was shut down cause a small craft shop a 1/4 mile down wind was using a silicone aerosol that was sucked in by the paint plant ventilation intakes and was leaving fish-eyes on the paint finishes of all the new cars.

4/- Good Luck with your project. The worst you can do is trash a good tube. No big deal !

Last edited by Stv; 09-21-05 at 07:28 PM.
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Old 09-21-05, 07:32 PM   #16
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I'm also curious about the results of this. As far as the issue happening on cars, I know that Costco is now filling new tires with nitrogen rather than compressed air. I guess the nitrogen passes through the rubber more slowly than oxygen. I found an article with some information about it....
Nitrogen Filled Tires

It sounds interesting, but I doubt that normal cyclists like us will ever be able to take advantage of the benefits
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Old 09-21-05, 07:36 PM   #17
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Originally Posted by Al1943
If the silicone can penetrate the tube what's it going to do to the sticky stuff that holds your rim tape in place?
My first thought was how will the silicone coat the entire tube? Seems it would centrifuge to the tread side.
I don't have any problem pumping my tires up every day. Still it sounds like an interesting experiment and I'd like to hear how it turns out.

Al
This is fun!

but (only somewhat) seriously though as this is entrely theoretical and I ain't gettin paid (my wife is actually yelling at me right now for typing in a bicycle forum instead of taking out the recycleables)...

The idea is that silicone cannot 'penetrate' the butyl tube, but would "try" to because of the air pressure trying to "force it" to. It would thusly block the air behind it from getting out.

As far as the rim tape goes. What adhesive? Quality rim tape is cloth and uses no adhesive as the tube pressure is more than enough to keep it in place.

As far as the "centrifugal slinging" goes, this should actually help distribute the silicone evenly.
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Old 09-21-05, 07:42 PM   #18
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Originally Posted by Stv
1/-Silicone is inert. It will have no reaction itself with the tube. Is air bleed from the valve or the porous tube material. Either way, the Silicone molecule will not have any effect, it is a lubricant.

2/-Have you attempted to source, let alone price a "pure" silicone?

3/-A little silicone goes a long way. Several years ago, I worked with a FORD assembly paint plant that was shut down cause a small craft shop a 1/4 mile down wind was using a silicone aerosol that was sucked in by the paint plant ventilation intakes and was leaving fish-eyes on the paint finishes of all the new cars.

4/- Good Luck with your project. The worst you can do is trash a good tube. No big deal !
Actually interestingly enough I just happen to have come upon some very high quality Silicon Oil (for RICOH FT Series Copiers) made by INFINICOM, multiple 16 oz. bottles of it (my cost $0.00, wanna buy some?). That is what started my feeble brain on this track as I saw it next to my machine.

Thanks for the good wishes; just playin' 'round; gotta do recyclables now...
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Old 09-21-05, 07:59 PM   #19
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Quote:
Originally Posted by yotool
The idea is that silicone cannot 'penetrate' the butyl tube, but would "try" to because of the air pressure trying to "force it" to. It would thusly block the air behind it from getting out.

As far as the rim tape goes. What adhesive? Quality rim tape is cloth and uses no adhesive as the tube pressure is more than enough to keep it in place.

As far as the "centrifugal slinging" goes, this should actually help distribute the silicone evenly.
Velox has a sticky adhesive on the back. If the silicone doesn't penetrate the tube all is well.

How will "cintrifugal slinging" (inertia) help distribute the silicone toward the rim side of the tube?
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Old 09-21-05, 08:04 PM   #20
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For all this debate I'm pretty happy to take 2 seconds to top my tires off every other ride.
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Old 09-22-05, 07:38 AM   #21
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For all this debate I'm pretty happy to take 2 seconds to top my tires off every other ride.
Yeah, me too, but that is besides the point!
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Old 09-22-05, 08:26 AM   #22
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For all this debate I'm pretty happy to take 2 seconds to top my tires off every other ride.
I was just about to say the same thing.
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Old 09-22-05, 09:51 AM   #23
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For all this debate I'm pretty happy to take 2 seconds to top my tires off every other ride.
Ah, but if figuring out how to make your tires go without topping-off for three times as long is the result of this conversation, then over a ten year period it will save you a lot more time than it took you to read and participate in this conversation.
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Old 09-22-05, 11:07 AM   #24
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Much ado about nothing. A 1 psi/day drop in pressure is not worth addressing. At that rate, you only need to top off the tires once or twice a week at 2 minutes per servicing.
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Old 09-22-05, 11:51 AM   #25
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Much ado about nothing. A 1 psi/day drop in pressure is not worth addressing. At that rate, you only need to top off the tires once or twice a week at 2 minutes per servicing.
True, but it's interesting (if only from a geek factor) to know if this actually works.
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