- Location
- The TerrorVortex
They remove most of the risk and all of the fun. Like engaging in oral sex with a condom on your tongue.
Page may contain affiliate links. Please see terms for details.
Lee_M
Guru
The mileage you do these days thats about one every decade isnt it Ben?
Pale Rider
Legendary Member
Given a rear puncture is more likely - and more of a nusiance - than a front, it would have been interesting to know how the bike rides with a Tannus on the rear and an ordinary tyre on front.
I'm tempted to suggest that combination might ride acceptably, since the front wheel plays the major part in steering and braking a bicycle.
chriscross1966
Über Member
- Location
- Swindon
Having learned to ride on a Raleigh Chopper I find I always brake on the back, the front is for emergency use only... A rear wheel skid was an acceptable cornering technique when I was ten, front brake locking came with a dentistry bill
Kell
Veteran
- Location
- High Wycombe/London
Back brake to slow.
Front brake (and back brake) to stop.
Front brake (and back brake) to stop.
Yellow Saddle
Guru
- Location
- Loch side.
The OP of this thread, Simon, kindly agreed to send me a couple of sections from his discarded Tannus tyre. I wanted to see for myself what the hype was all about and I quite frankly, found it intriguing that he hated these expensive solid tyres enough to cut them off after just a few rides. I received the sections, the original instruction brochure and some pins by post last week. Thanks Simon.
My initial thoughts for the request was to devise some sort of comparative rolling resistance test. At the time of my request I had to real idea of how I would do it so I opened a beer and gave it some thought, whilst mindlessly bouncing a superball against the wall. (That's how I'd like to phrase it for my post-Nobel prize interview). Then inspiration struck and I thought of the days when I played games in my workshop. Whenever I fitted a tyre I would finish off the exercise by throwing it away from me, onto the workshop floor and make it bounce back at me. It would magically bounce back because I put a hefty backspin onto it. It was my private little party trick. The trick revealed how much energy the wheel returned because the bounce is dramatically different dependent on the wheel configuration - inflation pressure, knobblies, slicks, sealant etc etc.
My inspiration was that I would bounce the Tannus and compare it to my own 25mm Conti at 60PSI. My inspiration had a flaw in it in that I only had a section of Tannus, now a whole wheel. Genious prevailed and I came up with the definitive ball-peen hammer trick. Instead of bouncing the wheel, I would bounce a hammer onto the tyre and see how much energy it returns to the hammer. Off came my front wheel and I started hammering it. I laid the Tannus flat onto a hard surface (granite kitchen top) and bounced the hammer on that. Same difference, give or take a large experimental error and poor eyeball technique. (This was after two beers).
Another inspiring moment hit upon me and I disovered that the Continental-shod wheel is actually losing more energy because I'm testing the entire wheel across its entire radius, through a set of spokes and into another complete tyre section. In other words, I should not bounce the hammer on top of the tyre when the wheel is standing on itself. I have to isolate a small section so that I only test one layer of tyre, not two and a set of springy spokes. I how positioned the wheel so that it hung off the corner of a workbench with the corner wedged between the spokes. Suddenly the hammer bounced really well. When compared to the Tannus I could just about convince myself that there was a dramatic difference and that the Tannus definitely had a higher RR than a pneumatic tyre and that I've proved it. I could just "feel" that the hammer bounces 1/10th of a mm higher from the pneumatic tyre than from the tyre. I've honed this "feel" after years of subjective compliance-testing of frames and wheels where I could "feel" that steel frames have about 0.3% more give than carbon frames and that 50gram lighter wheels gave me an edge of 0.5% on hills than heavier wheels.
Before publishing my findings in Scientific Bicycle Today, I procrastinated a bit and mulled over the results.
Another inspiration hit me between the eyes. Of course! Hysteresis (energy losses when rubber returns to a position before deformation), is not just caused by the deforming rubber against the road but also by other squirming, notably with tubular tyres, squirming against the rim itself. In other words, energy is lost by the compression inside the rubber and lost by the rubber (tyre) rubbing against the rim as your ride. This only happens with tyres which are either tubular (as in tubbies) or solid. Clincher tyres don't have these losses because they have to bottom to scrape against the rim in the first place.
Now I'm onto something, I said to myself. I then investigated the interface (fancy word for parts that rub) between Tannus and rim. It is hugely imperfect. The rim's shape only superficially matches the tyre's shape and to make things worse, the pins that hold the Tannus in place are spaced 50mm apart, leaving a large section not securely attached between the two pins. Here the tyre is a bit looser than directly under the pins, causing even more movement. If the rim doesn't have a flat spoke bed (none of them do), then there's a void between the Tannus and the rim itself, into which the rubber can morph in and out as you ride. More energy losses.
The third point of loss (if you've lost me so far, the other two were losses inside the rubber itself which is due to friction as the long curly chains or rubber polymer stretch and rub against other long curly chains of polymer and, squirming against the rim) is thanks to the generous (read stupid) tread on the tyre. It is really deep and causes large losses at the tyre's surface as the rubber squirms in and out of the voids in the tread. Had the tyre been designed smooth, it would have been better. However, then it would not have appealed to a naive consumer who believes that tyres must have tread.
So there you have it. These tyres have high rolling resistance because:
1) A rubber polymer always has higher hysteresis than a compressed gas.
2) The tyre does not fit perfectly into the rim and isn't attached with hard glue that prevents squirm.
3) There is thread squirm.
I have no idea how to test this, but a particular concern would be performance in the wet. Tyre rubber has been improved and improved for 100 years and still no better wet traction compound than carbon black has been found. Unfortunately, carbon black makes the tyre...err...black. Tannus are available in lots of colours, all chosen from the rainbow, which tells me there is zero carbon black in there. (How scientific is that deduction?)
So, (I've noticed on the radio that all scientists start answers with "so", so I'll do it as well), here are some pictures.
A scan from the information brochure showing you how to measure your rim width and choose the correct tyre. This means that fit is an approximation, unlike on a pneumatic tyre that automatically adjusts its fit. Room for improvement could include tyres more precisely matched to rims, better retention devices and perhaps even factory-fitting with hard glue.
A section of pins. These match the rim's internal width and apparently the tyres are shipped with a selection.
This is the pin fitted to the tyre. Round end facing downwards and pressed down on to click and hook behind the bead hook in the rim. Spaced 50mm apart.
Cross section of very expensive rubber. Note the tiny bubbles. To make the tyres sound like better value for money, these bubbles are called "nano voids". Note how the section intended to fit inside the rim will only approximate a rim's real shape and leave plenty of scope for squirming around, losing energy in the process.
A stupid quote hinting that the tyres contain some magic engine that kicks in at speed and somehow managed to reduce RR once in motion. Pure marketing genius. Ignobel Prize on its way.
Gratuitous tyre tread that serves just one purpose - to increase RR. Actually, make that two, it also suckers people.
And now I'd like to thank my producers, my dog, my co-author Et Al and of course Simon. Without them I would not be able to waste so much time.
My initial thoughts for the request was to devise some sort of comparative rolling resistance test. At the time of my request I had to real idea of how I would do it so I opened a beer and gave it some thought, whilst mindlessly bouncing a superball against the wall. (That's how I'd like to phrase it for my post-Nobel prize interview). Then inspiration struck and I thought of the days when I played games in my workshop. Whenever I fitted a tyre I would finish off the exercise by throwing it away from me, onto the workshop floor and make it bounce back at me. It would magically bounce back because I put a hefty backspin onto it. It was my private little party trick. The trick revealed how much energy the wheel returned because the bounce is dramatically different dependent on the wheel configuration - inflation pressure, knobblies, slicks, sealant etc etc.
My inspiration was that I would bounce the Tannus and compare it to my own 25mm Conti at 60PSI. My inspiration had a flaw in it in that I only had a section of Tannus, now a whole wheel. Genious prevailed and I came up with the definitive ball-peen hammer trick. Instead of bouncing the wheel, I would bounce a hammer onto the tyre and see how much energy it returns to the hammer. Off came my front wheel and I started hammering it. I laid the Tannus flat onto a hard surface (granite kitchen top) and bounced the hammer on that. Same difference, give or take a large experimental error and poor eyeball technique. (This was after two beers).
Another inspiring moment hit upon me and I disovered that the Continental-shod wheel is actually losing more energy because I'm testing the entire wheel across its entire radius, through a set of spokes and into another complete tyre section. In other words, I should not bounce the hammer on top of the tyre when the wheel is standing on itself. I have to isolate a small section so that I only test one layer of tyre, not two and a set of springy spokes. I how positioned the wheel so that it hung off the corner of a workbench with the corner wedged between the spokes. Suddenly the hammer bounced really well. When compared to the Tannus I could just about convince myself that there was a dramatic difference and that the Tannus definitely had a higher RR than a pneumatic tyre and that I've proved it. I could just "feel" that the hammer bounces 1/10th of a mm higher from the pneumatic tyre than from the tyre. I've honed this "feel" after years of subjective compliance-testing of frames and wheels where I could "feel" that steel frames have about 0.3% more give than carbon frames and that 50gram lighter wheels gave me an edge of 0.5% on hills than heavier wheels.
Before publishing my findings in Scientific Bicycle Today, I procrastinated a bit and mulled over the results.
Another inspiration hit me between the eyes. Of course! Hysteresis (energy losses when rubber returns to a position before deformation), is not just caused by the deforming rubber against the road but also by other squirming, notably with tubular tyres, squirming against the rim itself. In other words, energy is lost by the compression inside the rubber and lost by the rubber (tyre) rubbing against the rim as your ride. This only happens with tyres which are either tubular (as in tubbies) or solid. Clincher tyres don't have these losses because they have to bottom to scrape against the rim in the first place.
Now I'm onto something, I said to myself. I then investigated the interface (fancy word for parts that rub) between Tannus and rim. It is hugely imperfect. The rim's shape only superficially matches the tyre's shape and to make things worse, the pins that hold the Tannus in place are spaced 50mm apart, leaving a large section not securely attached between the two pins. Here the tyre is a bit looser than directly under the pins, causing even more movement. If the rim doesn't have a flat spoke bed (none of them do), then there's a void between the Tannus and the rim itself, into which the rubber can morph in and out as you ride. More energy losses.
The third point of loss (if you've lost me so far, the other two were losses inside the rubber itself which is due to friction as the long curly chains or rubber polymer stretch and rub against other long curly chains of polymer and, squirming against the rim) is thanks to the generous (read stupid) tread on the tyre. It is really deep and causes large losses at the tyre's surface as the rubber squirms in and out of the voids in the tread. Had the tyre been designed smooth, it would have been better. However, then it would not have appealed to a naive consumer who believes that tyres must have tread.
So there you have it. These tyres have high rolling resistance because:
1) A rubber polymer always has higher hysteresis than a compressed gas.
2) The tyre does not fit perfectly into the rim and isn't attached with hard glue that prevents squirm.
3) There is thread squirm.
I have no idea how to test this, but a particular concern would be performance in the wet. Tyre rubber has been improved and improved for 100 years and still no better wet traction compound than carbon black has been found. Unfortunately, carbon black makes the tyre...err...black. Tannus are available in lots of colours, all chosen from the rainbow, which tells me there is zero carbon black in there. (How scientific is that deduction?)
So, (I've noticed on the radio that all scientists start answers with "so", so I'll do it as well), here are some pictures.
A scan from the information brochure showing you how to measure your rim width and choose the correct tyre. This means that fit is an approximation, unlike on a pneumatic tyre that automatically adjusts its fit. Room for improvement could include tyres more precisely matched to rims, better retention devices and perhaps even factory-fitting with hard glue.
A section of pins. These match the rim's internal width and apparently the tyres are shipped with a selection.
This is the pin fitted to the tyre. Round end facing downwards and pressed down on to click and hook behind the bead hook in the rim. Spaced 50mm apart.
Cross section of very expensive rubber. Note the tiny bubbles. To make the tyres sound like better value for money, these bubbles are called "nano voids". Note how the section intended to fit inside the rim will only approximate a rim's real shape and leave plenty of scope for squirming around, losing energy in the process.
A stupid quote hinting that the tyres contain some magic engine that kicks in at speed and somehow managed to reduce RR once in motion. Pure marketing genius. Ignobel Prize on its way.
Gratuitous tyre tread that serves just one purpose - to increase RR. Actually, make that two, it also suckers people.
And now I'd like to thank my producers, my dog, my co-author Et Al and of course Simon. Without them I would not be able to waste so much time.
Attachments
Last edited:
Kell
Veteran
- Location
- High Wycombe/London
I have to say, I'm glad someone else went for these rather than me.
They seem like such a good idea in principle and I'd hoped that material technology had moved on from the solid rubber tyres you used to get. But it seems like either it hasn't, or the company that made these hasn't done made use of that technology.
I do find it hard to believe that it's not possible to make them - and make them roll as well as a 'normal' tyre - but maybe it's cost that makes it prohibitive.
They seem like such a good idea in principle and I'd hoped that material technology had moved on from the solid rubber tyres you used to get. But it seems like either it hasn't, or the company that made these hasn't done made use of that technology.
I do find it hard to believe that it's not possible to make them - and make them roll as well as a 'normal' tyre - but maybe it's cost that makes it prohibitive.
Fab Foodie
hanging-on in quiet desperation ...
- Location
- Kirton, Devon.
I'll take your word for that....
Yellow Saddle
Guru
- Location
- Loch side.
It is impossible to make them roll with as little resistance as a normal tyre.
On a pneumatic tyre you are compressing a little bit of rubber (the thickness of the casing), flexing a bit of sidewall and compressing a bit of air. Collectively, this has less losses than compressing a solid tyre.
The picture above shows why rubber has such high losses. These long molecules are matted like felt, and when stretched, they have to extricate themselves from the mat and this causes friction. It is like pulling on a piece of knotted string. When the pressure is released, it has to return to the original position and again, more friction as it settles in its bundled-up position again.
Air molecules on the other hand (or any other gas) are simple molecules that move about freely with very little friction between molecules. It's not cost, it is physics that makes it impossible. In addition, there's squirming, as explained above.
Kell
Veteran
- Location
- High Wycombe/London
I'm not saying that rubber is the answer.
Hence saying 'material technology' as opposed to rubber in my post above.
Hence saying 'material technology' as opposed to rubber in my post above.
Yellow Saddle
Guru
- Location
- Loch side.
The only material I can think of is Unobtanium. Perhaps you have better suggestions.
Kell
Veteran
- Location
- High Wycombe/London
I have no suggestions. This wasn't meant to be a Dragon's Den pitch. I just said I find it hard to believe it's not possible to create something which isn't a rubber tyre full of air.
Kell
Veteran
- Location
- High Wycombe/London
Something like these:
(Again, I've no idea how they perform or compare to traditional tyres)
View: https://www.youtube.com/watch?v=8hi5i-UODAE
(Again, I've no idea how they perform or compare to traditional tyres)
View: https://www.youtube.com/watch?v=8hi5i-UODAE
- Location
- The TerrorVortex
Looks like the same thing but even more precariously mounted.
