Tube or Tubeless?

[The Hodge]

Unless you've got the spare tube zip-tied to your wheel, you're still benefitting.

Yes ..I know ..Im not new to tubeless Ive been that way on my mtb's for as long as I can remember..it was said in jest ?

 

[Doug Stampfer]

I was wondering why I was losing pressure from my rear tyre so took it off, cleanded the bead, admired the bald centre & broken knobs then filed it back up with sealant & took it for a ride.....
I can see now ?

 

[KeithR]

Yes ..I know ..Im not new to tubeless Ive been that way on my mtb's for as long as I can remember..it was said in jest ?

I didn't really mean my reply for you - it's the internet, and you can guarantee that someone would take you literally and at face value unless they were told not to...

 

[mark.ai]

I'm surprised at how many people don't understand one of the fundamental reasons to run tubeless and that is the weight loss. Reducing weight from your wheels reduces unsprung mass and rotational mass. Roughly speaking rotational mass is three times harder to accelerate/decelerate than srpung mass.

I've always run tubes for ease of use, and keep considering the switch to tubeless, but not made the jump yet!

I'd like to know more about the weight difference though as I see it mentioned every so often. Any idea how much sealant you tend to use in a tire? Modern tubes weigh about 85g including the valve (Aerothan or Tubolito) and I keep thinking if you use 85ml of sealant then they will be about the same weight. I don't know what the density of the sealant is though, but assuming it is similar to water (so 85ml = 85g). And I've seen various recommendations on the web for how much sealant to use (probably from 40ml to 100+ml).

Other thoughts are that the weight of a tube is probably spread closer to the inside of the wheel - e.g. half towards the tyre outside and half towards the rim. Whereas maybe the sealant is more towards the outside of the tyre? Also if you ever top up the sealant in a tyre, then you are just increasing the weight of sealant further.

 

[Singletrackmind]

I've always run tubes for ease of use, and keep considering the switch to tubeless, but not made the jump yet!

I'd like to know more about the weight difference though as I see it mentioned every so often. Any idea how much sealant you tend to use in a tire? Modern tubes weigh about 85g including the valve (Aerothan or Tubolito) and I keep thinking if you use 85ml of sealant then they will be about the same weight. I don't know what the density of the sealant is though, but assuming it is similar to water (so 85ml = 85g). And I've seen various recommendations on the web for how much sealant to use (probably from 40ml to 100+ml).

Other thoughts are that the weight of a tube is probably spread closer to the inside of the wheel - e.g. half towards the tyre outside and half towards the rim. Whereas maybe the sealant is more towards the outside of the tyre? Also if you ever top up the sealant in a tyre, then you are just increasing the weight of sealant further.

I think the weight gains from going tubeless are in the eye of the beholder. Biggest advantage for me over years has been the vast reduction in flat tires. My riding partners who still use tubes have had many more flats than me riding the same trails together. Couple weeks ago noticed I ran into a cactus when loading my emtb on the bike rack. Had tons of needles imbedded in sidewalls and didn't even know it. Could see residue from where sealant prevented flat. Have run sealant in my tube on my previous dh rig with mixed results. One other advantage is you can run lower psi when going all natural which provides better traction. BTW, I'm not one of those riders who push the limits on how "low" they can go on their tire psi. I have baseline settings I use based on the types of trails/conditions I am doing that particular day.

 

[steve_sordy]

I've always run tubes for ease of use, and keep considering the switch to tubeless, but not made the jump yet!

I'd like to know more about the weight difference though as I see it mentioned every so often. Any idea how much sealant you tend to use in a tire? Modern tubes weigh about 85g including the valve (Aerothan or Tubolito) and I keep thinking if you use 85ml of sealant then they will be about the same weight. I don't know what the density of the sealant is though, but assuming it is similar to water (so 85ml = 85g). And I've seen various recommendations on the web for how much sealant to use (probably from 40ml to 100+ml).

Other thoughts are that the weight of a tube is probably spread closer to the inside of the wheel - e.g. half towards the tyre outside and half towards the rim. Whereas maybe the sealant is more towards the outside of the tyre? Also if you ever top up the sealant in a tyre, then you are just increasing the weight of sealant further.

Probably because I don't ride road bikes, I have never come across a "modern tube that weighs about 85g". I looked at the weight of the tubes that came with my 29x2.6" tyres and each tube weighed 239gm. Just in case that was a super heavy "e"tube, I checked the weight of the tubes that came on my last analogue bike. The 27.5x2.2" tubes weighed 189gm each. That is a massive difference to your 85gm. If your tubes are that light I'm astonished that you are not getting flats all the time. You must be a very light and skilful rider or maybe don't ride anywhere either rocky or near spiny stuff.

I don't know the density of latex sealant, I believe it floats in water, but I'll accept your assumption that 1ml = 1gm. I have 29x2.5" tyres on right now and I put 120ml of latex sealant in each tyre (the amount advised on the bottle). Less latex will work, but not as well or for as long. Any latex is better than none, for sure. That gives me a 239-120 gm weight reduction per tyre = 119g (4.2 ounces).

You are correct in your weight distribution assumptions. The mass of the tube will be equivalent to being half way between the rim and the outer diameter of the tyre. The sealant will be mostly on the outer inside surface of the tyre, but not exclusively because it does seal sidewall punctures. But let's assume that it is all at the outer.
The effect of rotating mass is felt by the square of the radius for any given speed. On a 29" tyre, the radius is 14.5", Lets assume that the centre of mass of the tube is at a radius of 13.5".
So, (14.5/13.5)squared is 1.15. The mass has an effect 15% bigger at the outer edge of the tyre than in the middle of the tyre.
But the mass of the tube is 239gm acting at the centre of the tyre (ie 1" below the outer inside face). Whereas the latex is 120gm, all at the outer; let's say the latex weighs half as much, a factor of two. That is more than enough to counter the radius effect of 15%. So even if you put a lot of sealant in, you are still better off than with a tube.

(Warning: It's a long time since I was at school, so my maths might need checking).

One of the claims made by tubeless enthusiasts is the reduced rolling resistance. It is false. It is the lower tyre pressure that leads to reduced rolling resistance because the tyre conforms to the trail rather than bouncing off it. And you can get that with tubes. On smooth surfaces of course, reduced tyre pressure will increase rolling resistance. But because the tubeless tyre no longer has a tube that is vulnerable to pinch punctures, the pressure can be lower and hence you get the reduced rolling resistance over rough trails. I read somewhere that friction between the tube and the tyre can generate rolling resistance, which may be why some riders use talcum powder between tyre and tube. But I have no idea whether this is only noticeable on high speed road bikes.

For me the biggest single benefit of going tubeless is the lack of downtime fixing punctures or changing tubes. This is particularly valuable trailside where it is normally raining or on a narrow trail where I'm blocking other riders. If I am travelling in company then I'd be holding everyone up whilst I attended to the puncture. If I was racing, I would lose many places. Whenever do punctures occur when it is convenient? In my time with tubes, I was getting one flat per 14 miles. Since going tubeless, I've had three flats in about 12 years. One was my fault because I failed to top up the sealant, the other two were defective tyres that split at the bead.

The unexpected benefit is the improved feel of the bike. Its hard to describe. It's a mix of improved grip, reduced rolling resistance and a lighter feel to the wheels. The rolling moment of inertia of the wheels is reduced and they are more responsive to acceleration, braking and turning. I used to notice this latter point more on my analogue bike than I do on my emtb though.

As for your concern about the tyre becoming increasingly heavy as you top up the sealant. I guess if the tyre never gets a puncture then no sealant will ever be lost. With time though the sealant dries out and ends up (in my experience at least) either as a thin skin everywhere on the inside of the tyre and frequently as an irregular shaped ball of dried latex rumbling about inside the tyre. I throw away the ball and sometimes scrape away the skin (but mostly not). I don't see an ever increasing weight as a problem at all, because in my case it isn't increasing by anything that matters. I suspect that I lose more weight in tyre wear than I gain in dried latex.

If your tyre and wheel set up is a proper tubeless system then you don't need sealant to make it hold air (car tyres don't). But we don't fit car tyres and we do ride in places that threaten the tyres, so sealant to seal up the inevitable punctures and stop them becoming flats is a very sensible measure.

 

[mark.ai]

Probably because I don't ride road bikes, I have never come across a "modern tube that weighs about 85g". I looked at the weight of the tubes that came with my 29x2.6" tyres and each tube weighed 239gm. Just in case that was a super heavy "e"tube, I checked the weight of the tubes that came on my last analogue bike. The 27.5x2.2" tubes weighed 189gm each. That is a massive difference to your 85gm. If your tubes are that light I'm astonished that you are not getting flats all the time. You must be a very light and skilful rider or maybe don't ride anywhere either rocky or near spiny stuff.

I don't know the density of latex sealant, I believe it floats in water, but I'll accept your assumption that 1ml = 1gm. I have 29x2.5" tyres on right now and I put 120ml of latex sealant in each tyre (the amount advised on the bottle). Less latex will work, but not as well or for as long. Any latex is better than none, for sure. That gives me a 239-120 gm weight reduction per tyre = 119g (4.2 ounces).

You are correct in your weight distribution assumptions. The mass of the tube will be equivalent to being half way between the rim and the outer diameter of the tyre. The sealant will be mostly on the outer inside surface of the tyre, but not exclusively because it does seal sidewall punctures. But let's assume that it is all at the outer.
The effect of rotating mass is felt by the square of the radius for any given speed. On a 29" tyre, the radius is 14.5", Lets assume that the centre of mass of the tube is at a radius of 13.5".
So, (14.5/13.5)squared is 1.15. The mass has an effect 15% bigger at the outer edge of the tyre than in the middle of the tyre.
But the mass of the tube is 239gm acting at the centre of the tyre (ie 1" below the outer inside face). Whereas the latex is 120gm, all at the outer; let's say the latex weighs half as much, a factor of two. That is more than enough to counter the radius effect of 15%. So even if you put a lot of sealant in, you are still better off than with a tube.

(Warning: It's a long time since I was at school, so my maths might need checking).

One of the claims made by tubeless enthusiasts is the reduced rolling resistance. It is false. It is the lower tyre pressure that leads to reduced rolling resistance because the tyre conforms to the trail rather than bouncing off it. And you can get that with tubes. On smooth surfaces of course, reduced tyre pressure will increase rolling resistance. But because the tubeless tyre no longer has a tube that is vulnerable to pinch punctures, the pressure can be lower and hence you get the reduced rolling resistance over rough trails. I read somewhere that friction between the tube and the tyre can generate rolling resistance, which may be why some riders use talcum powder between tyre and tube. But I have no idea whether this is only noticeable on high speed road bikes.

For me the biggest single benefit of going tubeless is the lack of downtime fixing punctures or changing tubes. This is particularly valuable trailside where it is normally raining or on a narrow trail where I'm blocking other riders. If I am travelling in company then I'd be holding everyone up whilst I attended to the puncture. If I was racing, I would lose many places. Whenever do punctures occur when it is convenient? In my time with tubes, I was getting one flat per 14 miles. Since going tubeless, I've had three flats in about 12 years. One was my fault because I failed to top up the sealant, the other two were defective tyres that split at the bead.

The unexpected benefit is the improved feel of the bike. Its hard to describe. It's a mix of improved grip, reduced rolling resistance and a lighter feel to the wheels. The rolling moment of inertia of the wheels is reduced and they are more responsive to acceleration, braking and turning. I used to notice this later point more on my analogue bike than I do on my emtb though.

As for your concern about the tyre becoming increasingly heavy as you top up the sealant. I guess if the tyre never gets a puncture then no sealant will ever be lost. With time though the sealant dries out and ends up (in my experience at least) either as a thin skin everywhere on the inside of the tyre and frequently as an irregular shaped ball of dried latex rumbling about inside the tyre. I throw away the ball and sometimes scrape away the skin (but mostly not). I don't see an ever increasing weight as a problem at all, because in my case it isn't increasing by anything that matters. I suspect that I lose more weight in tyre wear than I gain in dried latex.

If your tyre and wheel set up is a proper tubeless system then you don't need sealant to make it hold air (car tyres don't). But we don't fit car tyres and we do ride in places that threaten the tyres, so sealant to seal up the inevitable punctures and stop them becoming flats is a very sensible measure.

Interesting and useful thoughts there!

Yep the main reason I think about switching would be to avoid having to repair punctures mid-ride. But I've only had to do this once in the last 2 years, so it still hasn't quite tipped me to make the switch. I don't ride hard downhill at all, so it could explain a lot for my experience, however most of the trails are very rocky around here. But no cactuses luckily

The Tubolito and Aerothan tubes actually claim to be twice as puncture proof as "normal" rubber tubes despite being lighter. These are some of their example weights: (The plus tyre width versions are heavier). But also note the 45g ones (which I haven't tried!) - and which are mainly meant for emergency repairs only.

I have noticed some quality control issues with Tubolito in the past (like a slow leak from the valve over a few days), so considering trying the Aerothan ones at some point since they are a newer design made by Schwalbe.

 

[>moto<]

If you're going to the cost and effort to buy and fit superlight tubes, you may as well go tubeless. It's as quick, if not quicker to do. I have serious doubts that a tube tube weighing a 1/3 of a normal tube has twice the puncture resistance. If it works for you though....crack on.

According to their SDS, Stan's Notubes is slightly heavier than water (1.006g/cm3 vs 0.997g/c3 @20oC). Not sure about the others.

 

[MountainBoy]

Probably because I don't ride road bikes, I have never come across a "modern tube that weighs about 85g". I looked at the weight of the tubes that came with my 29x2.6" tyres and each tube weighed 239gm. Just in case that was a super heavy "e"tube, I checked the weight of the tubes that came on my last analogue bike. The 27.5x2.2" tubes weighed 189gm each. That is a massive difference to your 85gm. If your tubes are that light I'm astonished that you are not getting flats all the time. You must be a very light and skilful rider or maybe don't ride anywhere either rocky or near spiny stuff.

I don't know the density of latex sealant, I believe it floats in water, but I'll accept your assumption that 1ml = 1gm. I have 29x2.5" tyres on right now and I put 120ml of latex sealant in each tyre (the amount advised on the bottle). Less latex will work, but not as well or for as long. Any latex is better than none, for sure. That gives me a 239-120 gm weight reduction per tyre = 119g (4.2 ounces).

You are correct in your weight distribution assumptions. The mass of the tube will be equivalent to being half way between the rim and the outer diameter of the tyre. The sealant will be mostly on the outer inside surface of the tyre, but not exclusively because it does seal sidewall punctures. But let's assume that it is all at the outer.
The effect of rotating mass is felt by the square of the radius for any given speed. On a 29" tyre, the radius is 14.5", Lets assume that the centre of mass of the tube is at a radius of 13.5".
So, (14.5/13.5)squared is 1.15. The mass has an effect 15% bigger at the outer edge of the tyre than in the middle of the tyre.
But the mass of the tube is 239gm acting at the centre of the tyre (ie 1" below the outer inside face). Whereas the latex is 120gm, all at the outer; let's say the latex weighs half as much, a factor of two. That is more than enough to counter the radius effect of 15%. So even if you put a lot of sealant in, you are still better off than with a tube.

(Warning: It's a long time since I was at school, so my maths might need checking).

One of the claims made by tubeless enthusiasts is the reduced rolling resistance. It is false. It is the lower tyre pressure that leads to reduced rolling resistance because the tyre conforms to the trail rather than bouncing off it. And you can get that with tubes. On smooth surfaces of course, reduced tyre pressure will increase rolling resistance. But because the tubeless tyre no longer has a tube that is vulnerable to pinch punctures, the pressure can be lower and hence you get the reduced rolling resistance over rough trails. I read somewhere that friction between the tube and the tyre can generate rolling resistance, which may be why some riders use talcum powder between tyre and tube. But I have no idea whether this is only noticeable on high speed road bikes.

For me the biggest single benefit of going tubeless is the lack of downtime fixing punctures or changing tubes. This is particularly valuable trailside where it is normally raining or on a narrow trail where I'm blocking other riders. If I am travelling in company then I'd be holding everyone up whilst I attended to the puncture. If I was racing, I would lose many places. Whenever do punctures occur when it is convenient? In my time with tubes, I was getting one flat per 14 miles. Since going tubeless, I've had three flats in about 12 years. One was my fault because I failed to top up the sealant, the other two were defective tyres that split at the bead.

The unexpected benefit is the improved feel of the bike. Its hard to describe. It's a mix of improved grip, reduced rolling resistance and a lighter feel to the wheels. The rolling moment of inertia of the wheels is reduced and they are more responsive to acceleration, braking and turning. I used to notice this latter point more on my analogue bike than I do on my emtb though.

As for your concern about the tyre becoming increasingly heavy as you top up the sealant. I guess if the tyre never gets a puncture then no sealant will ever be lost. With time though the sealant dries out and ends up (in my experience at least) either as a thin skin everywhere on the inside of the tyre and frequently as an irregular shaped ball of dried latex rumbling about inside the tyre. I throw away the ball and sometimes scrape away the skin (but mostly not). I don't see an ever increasing weight as a problem at all, because in my case it isn't increasing by anything that matters. I suspect that I lose more weight in tyre wear than I gain in dried latex.

If your tyre and wheel set up is a proper tubeless system then you don't need sealant to make it hold air (car tyres don't). But we don't fit car tyres and we do ride in places that threaten the tyres, so sealant to seal up the inevitable punctures and stop them becoming flats is a very sensible measure.

Good analysis overall! I have always used conventional tubes with very few punctures as there just aren't that many stickers around the Pacific Northwest and the general wetness makes it more difficult for them to penetrate. And I appreciate not having a bunch of gunk inside my tires!

I recently picked up an Aerothan tube to try out. I got the 118 gram version (MTB+) for it's greater strength but I bet most 2.5"=3" wide tubeless tires in the wild have nearly that much sealant weight (if not more once they have been topped up a few times). So I don't really buy the weight argument and your analysis of rotational inertia advantaged the tube weight more than I would have guessed! In the end I just don't want to mess with slime. If I got frequent punctures I might have a different perspective.

 

[George_KSL]

I do believe the claim that tubolito are in fact more straight-on (pin-type) puncture proof despite being lighter, but I would say the opposite holds true for the most common type of defect, snake-bite against bead. That is where tubeless absolutely shines.

Where I live the terrain doesn't have many sharp rocks, so my preferable combination is thinner sidewalls (1kg for 29" 2.4" tyre., think EXO/EXO+, Grid Trail,... ) with inserts (CushCore). Now full CushCore (270 grams) + Sealant (120ml) adds a lot of weight :- )) but the ride feeling is insane. So damp, so cushioned, almost bulletproof except for tearing, but we don't have those sharp rocks, so. Thats 1400 grams for rear setup, and 1300g for front (CushCoreXC only). Kenevo SL. ( fun fact, on full-fat Levo I've put 27x2.8" Schwalbe BigBetty, 1400 grams, plus CushCorePlus 300 grams, and sealant 150 grams. 1850 grams setup. But it's full-fat, I don't even feel it, it's just smash-machine).

Plus CushCore, you don't need to keep spare tube, or any fixing kit. You can just ride home on flat tyre like nothing happened :- ). The weight savings are back!

 

[Growmac]

It's all been said on this thread already I think.

Here in the UK thorn punctures are a really big thing. Tubeless moves all the faff from during the ride to after the ride (checking pressures weekly and topping up sealant quarterly). Around here I was fixing a puncture every couple of rides, sometimes more. Now I'm tubeless with Rimpact inserts I've only had one puncture in 6,000 km and that was a slashed sidewall so I would have been walking anyway.

I personally find the lower pressures give more comfort and grip, but your results may vary, but it's 100% worth it if you're riding somewhere where thorns or impacts are causing you problems. Of course if you regularly change tyres then that's also a consideration. It's not that hard to do, but tubeless and inserts each add complication.

 

[MountainBoy]

I do believe the claim that tubolito are in fact more straight-on (pin-type) puncture proof despite being lighter, but I would say the opposite holds true for the most common type of defect, snake-bite against bead. That is where tubeless absolutely shines.

I doubt Tubolito and Aerothan are created equal but I don't have enough hard data to say - that's just my impression from absorbing a whole bunch of second-hand user experiences. Yes, I think the Aerothan are more reliable than Tubolito based on nothing more than antidotal evidence.

I think susceptibility to pinch flats with tubes made from the less elastic thermoplastic polyurethane is somewhat dependent on two things (besides air pressure, of course):

1) Schwalbe claims you can reliably run less pressure in the Aerothans vs. traditional tubes. However, if the tubes are over-stretched by inflating them past 4 psi before they are supported by the tire casing, I think pinch flats go way up. So, many of these pinch flats may be user-error.

2) The Aerothan tube I bought says it fits 29" x 2.5-3.0" tires. I think pinch flats might be less likely putting them in tire casings on the smaller end of that range because then the tubes are never over-stretched (because MTB'ers are always adjusting pressures up and down to suit conditions). A bigger tire casing, with higher pressures, can stretch the tube out and since the TPU tubes are not as elastic as butyl rubber, they may become a little more limp when pressure is reduced to suit other conditions, resulting in more pinch flats.

I doubt the manufacturer would tout the ability to run lower air pressure than butyl rubber if there was not some truth to it. I have 2.6" wide tires (Maxxis Rekon) with EXO+ sidewall protection and don't tend to explore the lowest pressure ranges anyway so I think I'll probably not have any issues with pinch flats. The Aerothan tubes feel less grippy and less rubbery than traditional tubes and I think this helps them avoid pinch flaats. It may also help to keep the area between the tube and tire dry.

I'm curious why you think the Tubolito's are more prone to pinch flats than regular butyl rubber tubes?

 

[steve_sordy]

As I have said earlier on this thread. I run tubeless. But I also carry spare tubes just in case I get a flat that the sealant won't seal. That has only happened 3x in 12 years, so not a lot to worry about. But each time I would have had a long walk and a ruined day if I hadn't had a spare inner tube to fit (plus the tools to remove the tyre and so forth).
When I got a mullet bike that became two spare inner tubes. And of course, because it's an emtb, they are big tubes! They add weight to my pack, but more importantly, they take up a lot of room. Elsewhere on this Forum, someone drew my attention to Turbolito inner tubes. These are expensive, but very light (45gm) and take up very little room. See pics.

Those Turbolito tubes are now out of their boxes and in a zip-lock sandwich bag at the bottom of my pack and they are just not noticeable.

 

[George_KSL]

I'm curious why you think the Tubolito's are more prone to pinch flats than regular butyl rubber tubes?

Just my armchair engineering :- )). I would say purely based on the thickness of the thing. I have no bad opinion of it, I definitely see the benefit of avoiding the faff with tubeless. Esp. with thin sidewalls, both seating the tire, and maintaining pressure is quite a hassle. But nothing is bigger nightmare to me than having to bother with fixing puncture while on ride. It's been so many years I've done it, tubeless made me very comfortable.