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Clarification:

I am not asking for a solution to punctures, or about the nuances of ride quality with the various solutions. I am asking whether one method of reducing punctures has been proven better than others through scientific testing.

Preface:

I often see people online using tubes with sealant rather than tire liners or puncture resistant tires, and wonder "why?" The slime is messy, can clog the valve, weighs more than liners, and does nothing to actually prevent a puncture, but rather waits until the puncture occurs to go into action filling it and (hopefully) coagulating in the hole. I've read that this really only works on small holes, too.

Purely anecdotal evidence:

I've ridden for the last eight years on the same route during my commute. I started with tire liners on regular tires, then went with Continental Gatorskins (Kevlar belted), and am now on my second set of Vittoria Randonneurs (double-shielded), and of the three setups, only ever had punctures on the Conti's -- at least two flats per year (grrr!). Zero flats on the Randos in nearly four years while laughing my way through the fields of glass. I see Schwalbe Marathons recommended more than any other brand, and while many say they've never had a flat with them, I also see some cyclists posting that they've had flats with those, too.

It just seems to me that there's no competition: double-shielding wins, IMO. It's less hassle that liners or sealant, and just as protective as liners/more protective than sealant, and generally weigh the same or less than sealant-filled tubes or tire-liners. Not to mention the cost factor over time.

Question:

Can someone explain the advantages of using liners or sealant over puncture-resistant tires, specifically relating to resisting punctures? Have any scientific studies been done to compare the three methods?

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  • 1
    No setup (beyond solid tires) is flat proof. Continental Hardshells are more puncture resistant and longer lasting than the Gatorskins, at the cost of a harder ride and less traction.
    – Rider_X
    Jun 23 '15 at 15:39
  • 1
    I have no expectation of finding a puncture-proof solution. I already have my "solution" on my bike. I'm wondering why some choose to use sealant or tire liners over puncture-resistant tires, and if there's some advantage I'm missing.
    – digijim
    Jun 23 '15 at 15:46
  • 1
    @digijim - Your question explicitly asks about nuances of ride quality, then deviates into questions about scientific analysis of puncture resistance. I think you need to pick one and rephrase your question. Ride quality has many components (e.g., suppleness, grip, rolling resistance). Puncture resistance impacts these characteristicsl. If, as you state in your comment, you are only interested in puncture resistance then a solid tire will be scientifically best.
    – Rider_X
    Jun 23 '15 at 19:12
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    @Rider_X - Show me where I explicitly ask about ride quality, because I honestly don't see it. Everything I read in my question relates to puncture resistance.
    – digijim
    Jun 23 '15 at 19:20
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    I've only ever had one puncture in my Forte Metro-K tires (Kevlar belted), in about 3000 miles of riding, and that was when the tire was nearly worn out. Prior to switching from standard tires I got about one puncture every 200 miles. Jun 24 '15 at 0:18
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There is more to tire set-up than just puncture proof. Many are also interested in tire suppleness, traction and rolling resistance. Tubeless tires are the in thing at the moment because tubeless construction take material away (aka the the tube) and allows lower pressures, which results in a more supple tire, that has more traction and often less rolling resistance.

Supple tires can often roll faster and with less effort as they deform more easily to surface imperfections. This translates into a smoother ride and less pedaling effort and more traction. Many of the puncture proof setups add material to the tire making the tire carcass stiffer, this in turns means it takes more energy to deform the tire when rolling (or encountering a bump), which in turns results in a harsher ride and a higher rolling resistance (the energy to deform the tire has to come from somewhere; i.e., forward momentum).

Summarizing:

  1. Tire Liner - Cheap and reusable as it can be applied to current tires, but has a fiddly set up (e.g., getting the liner to stay in place), will reduce suppleness of the tire and does not provide puncture protection on the side wall.
  2. Puncture resistant tires - These have what is in essence a liner built into the tire carcass. Because of the unified construction should be more supple build than a tire liner and vary the degree of coverage. Different manufacturers and models will have different trade-off between suppleness and puncture resistance.
  3. Tubeless - Primary goal is really to create a lighter, more supple tire, that can be run at lower pressures, the setup also happens to have good puncture resistance properties if sealant levels are maintained. Mounting a tubeless setup can be a hassle (i.e., you need high pressure to seat the tire), sealant is required and handles sealing the system including handling punctures. Sealant also needs to be topped up every few months as it dries out, and without sealant you lose puncture protection. The setup also requires wheels with tubeless compatible or tubeless ready rims, tubeless tape, and tubeless valves are also required. The design goal was less to be "better" than (1) or (2) in terms of puncture protection, but optimizing the tire for a different set of criteria (i.e., weight, suppleness, traction, rolling resistance and puncture protection).

If puncture resistance is your only concern then your "double-shield" setup looks like a good solution and will be easier than tubeless.

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    Tubeless is all front loaded for time required as well. It is the lightest, best "feeling" ride but requires known. up front effort and little effort afterwards. Liners and puncture resistant tires feel less nice while riding and require the same amount of effort as initial setup when they fail (or more). It's an Iron Man vs Wolverine question. Iron Man can withstand quite a bit, but once his armor is penetrated, he's pretty much done. Wolverine can sustain the same damage, but recover from it and keep going. Jun 23 '15 at 16:19
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The tyre slime is particularly good at sealing pin-prick holes... I bought a new ride on mower, and within half an hour got a puncture on the front 2 ply tyre.... I then installed the supplied Goo, and it sealed the leak.

After 3 years of cutting grass (next to Hawthorn Hedges) the front tyres finally needed some air, so I took them off to find the new hole... Each tyre was riddled with over 14 punctures, and the tyres still had many thorns in them.

So the Goo really works, I repaired one tube with a dozen patches, and treated myself to a new tube on one side. I never realised the Goo had sealed so many holes. I also have used it in a slow puncture on a car tyre, also with good results.

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    Hi and welcome to bicycles. SE. This doesn't answer the question, which is asking for a comparison of which approach is better - you've only mentioned one method.
    – Móż
    Jun 13 '16 at 21:46
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    As an aside, the goo can lead to an expensive repair on a car tire. A lot of cars have tire pressure monitoring system (TPMS) sensors which are built into the valve, and the goo can interfere with the sensor. Depending on the car, replacement of the valve/TPMS sensor can run hundreds of dollars (for my car, the sensor+valve was a bit over 100 dollars, excluding charges for programming it).
    – Batman
    Jun 13 '16 at 22:26
  • What pressure do your tractor tyres run? I would guess fairly low MTB-level pressures.
    – Criggie
    Jun 14 '16 at 3:53
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    While it doesn't answer the main thrust of the question, this answer does report on the effectiveness of one approach. I'm voting to keep it.
    – andy256
    Jun 16 '16 at 1:16
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First off and most obvious choice for preventing flats is your first line of defense and that's the tire, plain and simple. Yes I agree that Schwalbe Marathon model line of tires are the best against flats. You didn't say what tire size you use or what you use your bike for. If you use your bike for loaded touring then the best you can get is the Marathon Plus HS440, this is as flat resistant of a tire you'll find anywhere, plus it wears like iron, it's not uncommon to hear reports of 6,000 miles on a tire, but it's not a lightweight tire at 900 or so grams, and the ride quality is a bit stiff, the rolling resistance isn't bad about in the middle of the road for similar tires. The company calls these tires flatless...I doubt that, I do use one of the rear on my touring bike and haven't had a flat but any tire can have something unexpectedly bad happen.

If you want a highly flat resistant tire that's no so heavy as the Marathon 440 and rolls faster than other tires of it's kind, it will last about 4,000 miles and probably longer on the front, which is where I put mine at, is the Marathon Almotion HS453. I haven't gotten a flat on these either but they are on the front and fronts get far fewer flats than the rear does. I know you're thinking it's an odd thing that I did by mixing up the tires on my bike but I wanted to reduce weight a bit while decreasing rolling resistance a bit as well, and they do feel better than the OEM Kenda Drumlin tires that came with my bike, those Kenda tires weighed 1,600 grams a piece so I saved quite a bit of weight doing what I did.

Beyond the tires I haven't done anything else on my touring bike, when I was using the Kenda's I did have a Panaracer FlatAway Kevlar liner in the rear only, but while it wouldn't allow me to push a tack through it when it was new it slowly wears out inside the tire which deposits yellow fuzz all over the tube, and before I replaced the tire I got a couple of flats in a roll, so when I pulled out the liner I noticed it was thin and I was able to push a tack through it easily. I have decided for the time being to go without liners, I think with the tires I'm using all it would do is add unnecessary weight and not gain anything in flat protection.

The reason I don't use liners any more in my touring bike is similar to why I don't use sealants. I don't like sealants to begin with, sure initially the liquid is lighter than a poly liner and they do work at sealing tiny holes, but after 3 or so months you have to put more in and then that liquid becomes heavier than a poly liner. Of course with a tubeless tire you don't have a choice you have to use sealants which is why I will never use tubeless tires, plus if you have a flat with a tubeless on the road you have to put a tube in anyways, just seems stupid to me, and it seems equally stupid to put in sealant all the time with that weight going up and up every time you add it to a tubed tire as well.

So I think that if you have a good flat resistant tire all the other weird stuff isn't needed. Now on skinny road tires if you ride in an area prone to have thorns then you may need a liner, in that case I would use the Mr Tuffy Lite liner, I haven't used those yet because I was using the Panarace Flataway in my rear road tire as well, but since that liner also wore out I will be buying the Mr Tuffy Lite liner for use in the rear only, then put the other liner (it comes with 2 in package) in my commuter rear tire.

There is also new poly tubes on the market promising to be more resistant to flats than any other type of tube. Problem with those is the cost hovering at around $40 each! The other problem, which I have emailed several places that make these tubes and none will respond to my question, is that you have to use a special glueless patch they make and will sell you, what they won't mention on their websites or tell me is if that patch is a permanent patch or just to get me home solution then have to throw the tube away because the patch won't take to the tube for more than 24 or so hours. I'm not throwing away a $40 tube!! So until they can promise us that the glueless patch is a permanent fix I cannot suggest that alternative for flat protection.

Sorry for the long answer but I hope it helps someone.

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Can someone explain the advantages of using liners or sealant over puncture-resistant tires, specifically relating to resisting punctures?

I can see several advantages.

Firstly, tires that are puncture resistant enough to get puncture as rarely as a car tire has punctures require so much rubber or other material to resist intrusion of sharp objects that the rolling resistance will be terrible.

Sealant will be similar to a cyclist fixing the puncture, not reducing rolling resistance but rather letting punctures happen and then take care of these after the puncture has happened. The rolling resistance will be way lower with this approach.

My opinion about different types of sealant, including tubeless sealant, is that it's messy, can affect usage of adhesive tire boots in case of tire sidewall damage, may require frequently adding new sealant at great cost and trouble, and not as permanent as a glue-type inner tube patch. So that's why I use tires with inner tubes and patch manually. It's not a big deal to patch once per 3000 - 5000 km. (Besides, in the last 3000 km, the only type of tire damage I had was a sidewall tear which no amount of sealant would have fixed -- I put in a tire boot that would not adhere to the tire sidewall if there was messy liquid sealant.)

Also an advantage of both liners and sealant: if you have special needs for tires, such as needing to use studded winter tires, or having an odd tire size such as in a Brompton folding bike, you have only a limited choice of what type of tire to use. You may not be able to find a suitable tire that is puncture resistant enough. By using either sealant or liner, you may be able to use a tire that's actually available for sale.

The slime is messy

Agreed, a valid reason to avoid any form of slime or tubeless sealant

can clog the valve

A very valid observation

weighs more than liners

I'm not convinced about this. My Tannus tire liners weigh more than typical amounts of tubeless sealant. Also remember that you don't need the weight of an inner tube in tubeless systems

and does nothing to actually prevent a puncture, but rather waits until the puncture occurs to go into action filling it and (hopefully) coagulating in the hole

Bingo! You nailed it. Due to the special needs of bicycles, rolling resistance must be low, hence tires must be such that they puncture frequently, hence punctures need to be dealt with after they happen.

I see Schwalbe Marathons recommended more than any other brand, and while many say they've never had a flat with them, I also see some cyclists posting that they've had flats with those, too.

Here in the winter they use a particularly coarse and sharp gravel to prevent pedestrian injuries during the icy winter. They also erroneously place the cyclists and pedestrians at the same roads, so cyclists have to deal with the horrible gravel causing punctures every 100 km. My solution is Tannus tire liner. I have heard that not even Marathon Plus survives forever in the sharp horrible gravel.

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