What Work Is Being Done For Serious Non Pneumatic Tires?
#51
Tragically Ignorant
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#52
Cycleway town
Well, I've now fitted these. With a pair of new tyres, identical to the old ones. Sizing as follows:
Rim - 559 x 50
Tyre - 559 x 60
Tube - 26 x 1.9-2.1
Armour - 559 x 50-63
First thing you notice here is that my sizing doesn't make me a great example. Yes, I'm running 50mm wide rims, and that means Tannus' claims of run-flat ability can be laughed at for starters, especially given the paper-thin, relatively small but baggy 2.35in Schwalbe Fat Frank tyres. These are already excellent for pinch flats though, staying inflated even when the rim itself is broken by a kerb! So Tannus' claims of pinch-flat protection will hopefully mean it helps protect the rim itself from damage. This is very much still valid for me, despite 60mm tyres, because the bike weighs some 45kgs and near ten of them are in the back wheel...
Anyway, despite the wheel with, the armour did tuck nicely into the rim (various sizes are available, and if you're in-between sizes you cut the Armour's skirt shorter). In fact, at low pressure, it was possible to fit it just like a tyre, without the tyre..
Fitting was easy, I put the armour and tube in the tyre first, and offered the lot onto the rim. The first side went on as normal, the second side was just a case of tucking the armour into the rim first, then the tyre's bead as normal after.
So what do they ride like? Well I was expecting worse, but the actual rolling ride quality is slightly improved. It feels a touch more refined. At float level.
There is a downside, though. But it's difficult to pinpoint. Firstly, I've fitted new tyres, so it might just be the extra tread, but I can feel the tread itself a bit more. More the point though, the drivetrain feels a little more.. apparent. I can really feel the chains (I have two on this child-back tandem). This too might not be the armour, but having swapped the wheel out and subsequently had the derailleur re-aligned. Still, having just lubricated it all, I've never experienced this before.
A bike always feels slightly different when It's put back together. Fact is it runs fine, rides fine, handles as well as it ever has and I've no complaints - hopefully it will be a long time before my next update!
Rim - 559 x 50
Tyre - 559 x 60
Tube - 26 x 1.9-2.1
Armour - 559 x 50-63
First thing you notice here is that my sizing doesn't make me a great example. Yes, I'm running 50mm wide rims, and that means Tannus' claims of run-flat ability can be laughed at for starters, especially given the paper-thin, relatively small but baggy 2.35in Schwalbe Fat Frank tyres. These are already excellent for pinch flats though, staying inflated even when the rim itself is broken by a kerb! So Tannus' claims of pinch-flat protection will hopefully mean it helps protect the rim itself from damage. This is very much still valid for me, despite 60mm tyres, because the bike weighs some 45kgs and near ten of them are in the back wheel...
Anyway, despite the wheel with, the armour did tuck nicely into the rim (various sizes are available, and if you're in-between sizes you cut the Armour's skirt shorter). In fact, at low pressure, it was possible to fit it just like a tyre, without the tyre..
Fitting was easy, I put the armour and tube in the tyre first, and offered the lot onto the rim. The first side went on as normal, the second side was just a case of tucking the armour into the rim first, then the tyre's bead as normal after.
So what do they ride like? Well I was expecting worse, but the actual rolling ride quality is slightly improved. It feels a touch more refined. At float level.
There is a downside, though. But it's difficult to pinpoint. Firstly, I've fitted new tyres, so it might just be the extra tread, but I can feel the tread itself a bit more. More the point though, the drivetrain feels a little more.. apparent. I can really feel the chains (I have two on this child-back tandem). This too might not be the armour, but having swapped the wheel out and subsequently had the derailleur re-aligned. Still, having just lubricated it all, I've never experienced this before.
A bike always feels slightly different when It's put back together. Fact is it runs fine, rides fine, handles as well as it ever has and I've no complaints - hopefully it will be a long time before my next update!
#53
SE Wis
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#54
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If it's about saving un-sprung weight then pneumatic is your best option. A compressible fluid such as air is a lot lighter then trying to get a non-compressible solid to flex and behave in a similar manner.
#55
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https://www.wired.com/2013/09/hankook-i-flex/
#56
Senior Member
There are probably weight savings possible by making the wheel itself a wear item; but I still don't see a combined wheel/tire as a good idea.
#57
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Taking this thread seriously for a second, I remember these making the rounds at some trade shows a few years ago. Looks like the idea is still kicking but I have yet to see any in the real world.
https://bikerumor.com/2019/01/22/new...to-bikes-more/
And:
https://bikerumor.com/2019/01/22/new...to-bikes-more/
And:
#58
Cycleway town
When an impact strikes a pneumatic tyre, the energy is absorbed by the entire tyre; as the affected area deforms, the air pressure is raised throughout. The spring-rate is shared all the way around.
Every non-pneumatic tyre I've seen fails to utilise such a strength. The affected area alone has to dampen the impact.
I really can't see anything working like a pneumatic tyre until it's able to spread the energy like a pneumatic tyre.
Every non-pneumatic tyre I've seen fails to utilise such a strength. The affected area alone has to dampen the impact.
I really can't see anything working like a pneumatic tyre until it's able to spread the energy like a pneumatic tyre.
#59
Senior Member
Right. And as a result, air-free tires are much harder on rims. I remember a few reports of converts breaking their rims and then treating it as a coincidence. Nope, it was caused by the tire.
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"Because overall weight is reduced, fuel consumption is lower and handling has the potential to be improved as unsprung weight is removed from each corner."
https://www.wired.com/2013/09/hankook-i-flex/
https://www.wired.com/2013/09/hankook-i-flex/
BTW this article is over 6 years old. The reason you still don't see non-pnuematics is because you're fighting against physics. You are trying to make a non-compressible, heavy thing be a compressible, light thing. If non-pneumatics were so amazing, so revolutionary. They would be here today and not be a thing of yester-century.
Maybe I'm wrong. But I doubt I'll be wrong anytime soon.
Last edited by 86az135i; 11-14-19 at 09:05 AM.
#61
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Thank you all!
Folks:
Sorry for being invisible for a long time. Some serious stuff came up and I did let things slide. I am happy, though, in seeing what alternatives are out there and what may be coming down the road in the future.
I do have to accept that this is a challenging problem because of different riding conditions and being able to use different air pressures.
I am a bit excited at the possibility of better conform and stretch technologies that can withstand a pin/tack/broken glass/whatever without getting punctured. Perhaps would this be the answer, along with steel belts or radials?
I currently have schwabbles and I have been having problems with broken glass working its way through the tread (not the sides) and causing flats. I average (here in Bellingham, Washington) about three flats per year; all were broken glass that has pierced the center of the tread and into the tube.
Mark Allyn
Bellingham, Washington
Sorry for being invisible for a long time. Some serious stuff came up and I did let things slide. I am happy, though, in seeing what alternatives are out there and what may be coming down the road in the future.
I do have to accept that this is a challenging problem because of different riding conditions and being able to use different air pressures.
I am a bit excited at the possibility of better conform and stretch technologies that can withstand a pin/tack/broken glass/whatever without getting punctured. Perhaps would this be the answer, along with steel belts or radials?
I currently have schwabbles and I have been having problems with broken glass working its way through the tread (not the sides) and causing flats. I average (here in Bellingham, Washington) about three flats per year; all were broken glass that has pierced the center of the tread and into the tube.
Mark Allyn
Bellingham, Washington