[Udi]

Is there some obvious reason this wouldn't work reasonably well?

I must be the only person that despises the messy latex solutions (probably because I watched a household of people messing around with tubeless constantly last bikepark season), everything from cut sidewalls to slow leaks to stuff blowing up during inflation/seating/sealing attempts, and the general mess and waste of time involved.

So (with the caveat that this might be something only I care about), would running a lighter tube with an insert potentially offer a setup that allows lower pressures and is more durable / more difficult to flat while maintaining a reasonable overall weight? Would the assembly process make it a non-option with some combinations?

Most people I know running tubeless aren't using 50g of the goop, more like 100-150g+.
Insert weights are: 260g Cush Core, 130g "DH" Huck Norris, 90g "standard" Huck Norris.
A freeride tube (about as light as I can get away with for DH) weighs 310g.

My goals are to run less pressure, get less flats, and maybe get a little damping - while hopefully keeping the total weight around 300g (350 would be fine, maybe not 400+). I don't want any latex/goop.

Could I use an insert and a lighter tube to take up the remainder of the weight to achieve this? The CC shape looks way better, but 250g doesn't leave much weight for a tube (and it sounds hard enough to install without squeezing in a tube) - on other hand I'm not sure the other designs would stay in place well enough to keep the tube protected, the HN shape looks lame.

Maybe @mtg / @Westy / @Happymtb.fr / @buckoW have some thoughts, others appreciated too.

Edit, and the real @slimshady.

 

[Westy]

I have actually thought about this a bit. I don't see why a tube wouldn't work with cush core as long as you could get the stem through the rim. Might be as simple as cutting a hole in the liner and finding a tube with a long enough stem to reach through. As the tube has to take up less space you could get away with a smaller size than would be normally required for the size of tire.

My only reservation would be that the foam liner in a tubeless setup lives wholly within the pressurized tire and would only compress when a rock or such pushes the tire into the liner. A tube would compress it against the tire and rim. This could make it less compliant and possible give the tire a wonky shape. Only one way to tell, try it. Or better yet, convince someone else to try it.

Edit: assuming CC is closed cell foam it would be just as compressed in a tubeless setup, just not pressed into the tire/rim

 

[Jm_]

I had two tubeless issues in two days this week. One, my schwalbe tire delaminated at the bead, which would have caused any tire to fail IMO, only it would have been more sudden with a tube because I wouldn't have noticed a little bit of air leaking down/sealant with a tube, it just would have popped through and blown. The other was a bad burp during a race when I crashed, let out enough pressure that the tire couldn't hold it's own and stupidly I brought bear spray instead of my pump. A tube would have pinched in the same situation though and the "fix" in this case is just to add the air back, simple as pie.

Unless the tire is dipshit tight like my WTB, one shouldn't be fooling with resetting tubeless out in the field all that much, just throw a tube in. Chances are if the hole is big enough one of those tire plugs won't work. It might, but if it doesn't you'll save a lot more time just to throw a simple boot and tire in there, rather than figure out after a few cycles of adding air and sealant (if you carry that) that it's not going to work. Save that for home repair. The WTB tire can't be put on by mere mortals anyway, so I fear when that thing gives out again, although I punctured it good last year and somehow managed. Maybe keeping it on keeps it "stretched" a bit. You can fill it up with a bike-pump though, totally sealed.

On the flipside, with trips to TX and AZ recently, I found all sorts of thorns and other shit embedded in my tires and never had an issue. Even some damn glass out in Texas where the thing sealed up from the puncture. Flats are such a rarity for me now, even with the bead-thing above it didn't go flat all the way, I was able to keep adding some air and keep sealing the damn hole resulting from the tire COMING APART, although that wasn't going to last forever.

Tubeless has become very efficient for me these days, I've found lots of methods to make it all work, even with my gigantor fat bike tires with a floor-pump, stuff that I kick myself for not figuring out easier. A little messy sometimes, mostly when a little makes it past as the bead is popping into place (if you added the sealant before setting the bead, which I sometimes do to save time).

I'm curious how this will allow for lower pressure. You are expecting the foam to resist the rocks and other impacts? I would think that when you encounter a sharp rock that has the potential to pinch, the amount of force imparted will greatly exceed the ability of foam to protect the rim. On a drop/jump/g-loading event I think it would work fine, but a sharp rock? Will there be enough pressure to keep the tire from moving on the rim and possibly rolling off? Will this cause the tire to "self steer" like the fat-tires do, where the tire tries to turn more into the turn than you want? In the above situation where I had the burp, I still rode out, abet with something like 15psi in my tire, still enough to limp back, but holy crap I wouldn't want to ride the bike like that, sidwalls not holding up, wobbly as hell, etc.

Curious how this works out.

 

[daisycutter]

https://www.pinkbike.com/news/opinion-why-have-tires-sucked-for-so-long.html

 

[mtg]

@Udi
As to why your roommates had so many issues, some combinations just don't work well (although those keep getting more rare). Some wire bead DH tires are not tubeless compatible, but if your friends were running them tubeless anyway, that could cause issues, especially tires blowing off rims. Rim dents make slow leaks happen much easier, and makes seating tires tubeless much harder. With dented rims and non-tubeless tires, yeah, that's a recipe for disaster. Don't do that. The mess of tubeless occurs either when trying the seat the beads, or when fixing a flat, FYI. If the bead can be seated quickly, and you don't flat, there's no mess.

This season for me has had quite a bit of tire experimentation, as I got fed up with smashing rims. Before I get to my thoughts on your direct question, this season's tire evolution should be useful info.

My flats have been almost entirely from pinch flatting a tubeless tire, which may slice it, and usually dents the rim. I almost never slice sidewalls, and my setup is chosen accordingly.

- Initial setup when I built my new ride-everything bike: 2.3 Maxxis EXO front, 2.3 Maxxis DoubleDown rear. Only a handful of rides in, I smashed the rear rim to the point where it would no longer hold air. Damnit.

- Bent the bead back, put Huck Norris in, and kept the DD tire. Improvement and lasted quite a bit longer, and I could feel some impact attenuation with the HN insert. The rear rim still was getting some dents, albeit smaller. Then, on a big ride, one of those dents started leaking air. In goes a tube.

- Now, I've run Huck Norris with a tube. I put the foam insert between the tube and the tread. It felt weird, like the tread was squirming/sliding on the insert, however I was able to finish the ride on it. I also don't expect there to be much pinch flat resistance, as the tube would get pinched more often, albeit at lower peak force.

- Rim bead dents straightened again, DD tire back on with Huck Norris. The insert has a lot of cuts in it by this point. Without HN, I think the rim would have been smashed many times, not just dented.

- I realized that tire volume is as useful (to a certain extent) as HN at preventing rim dents. The DD tires are about 2mm smaller in width than an equivalent EXO tire. It literally bottoms out more often. Riding a different bike with 2.4" EXO rear tires confirmed that.

- Once that 2.3 EXO/DD tire combo wore out, CushCore with 2.4" Ardents went on. Yeah, the Ardent in the front is sketchy on loose terrain. It'll be replaced with a DHF later.

- CushCore has a very noticeable bottom out bumper that begins about halfway through the tire compression, and the damping is also very noticeable when descending chunky terrain, including braking. I took their advice and run 5psi lower than normal, which puts me at 22/24 psi. That seems ridiculous, and those tires would rip right off the bead, and destroy the rims on the first descent without CC. But with CC, it works really well, albeit the Ardent could use some bigger side knobs.

"So (with the caveat that this might be something only I care about), would running a lighter tube with an insert potentially offer a setup that allows lower pressures and is more durable / more difficult to flat while maintaining a reasonable overall weight? Would the assembly process make it a non-option with some combinations?"

In the name of experimentation, you could try it. That's the trail side repair method for both Huck Norris and CushCore. I did with Huck Norris as a repair and it felt weird, though. It would be quite heavy to run CC and a tube, and the tube might get pinched easier since it would be pounded into the foam on a regular basis.
With rims in good shape (I replaced my rear rim before installing CushCore), tubeless compatible tires that work well (ie not 120tpi 2.8's), and a foam insert, tubeless setup is usually easy. The foam inserts actually make it easier, as they push the tire beads outward towards the rim bed. CC makes it really easy, as the tire bead is pretty much fully seated upon install.

From me buying and trying foam inserts, Huck Norris is best if you're weight conscious or don't have too much of a problem with smashing rims, but want some protection. CushCore is a totally different experience that allows running 5psi lower pressure, adds tire damping, lots of bottom out resistance, and sidewall support.

"My goals are to run less pressure, get less flats, and maybe get a little damping - while hopefully keeping the total weight around 300g (350 would be fine, maybe not 400+). I don't want any latex/goop."

You just described CushCore. My experience says it takes a few extra minutes per tire to install, and with the bead pretty much fully seated, the sealant stays in the tire upon inflation. After that, you can run lower pressure, have tire damping, and less flats.

FYI on my riding this season: heavy on the trail riding and xc, but still with plenty of chunky descending and some bike park days.


TL;DR: Start from the top and read until you get back to here.

 

[toodles]

I just finished a 4 hour enduro (yeah @kidwoo I know you love them) and I've had like 4 pints so this might be a retarded thing to say, buuuuuuut.... wouldn't putting the Cushcore insert outside of the pressurised part (ie running a tube mean that it is being compressed by the tube against the rim?

That might render its bump absorbing capabilities a fair bit less effective if it is already compressed. I mean it's only 25- 35 psi versus their intended square edged hits but maybe worth considering.

Also, the problems your housemates had with tubeless might have more to do with the fact they're a bunch of filthy Aussie dodgy bastards and shouldn't be taken as a reflection of the merits of the technology they're trying to operate whilst munching KFC and watching re-runs of the Big Lez show.

*edit* Nevermind Westy already said what I was trying to say. My comments regarding the filthy unshaven Aussie scum still remain valid.

 

[troy]

How about making a "semi tubular" tire? Why not just put the HN insert in (for pinch flat protection) and glue together half of the inner tube to the tire itself, that would prevent burping?

 

[Happymtb.fr]

@toodles
Regarding cc with a tube, since it is closed cell foam, the pressure from inflating with or without a tube will compress it.
@Udi
It might be difficult to seat the bead properly when combining cc with a tube... just a thought
roadies have plenty of expensive valve stem extender if you cannot find a tube with the right length from the start.

I have been considering gluing a tube to a tire, a bit like @troy suggest. Like I see it, it would reduce risk of pinch flat and eliminate the risk of burping. But rim protection would not be improved unless something damping material is added... and repair on the field would be difficult, let alone gluing the tube properly and in a way that will allow you to mount the tire without flatpinching the tube with the tire levers...
I did not pursue this idea yet since it is summer here and I am thus better off riding my bike! but it is winter on your side of the globe, so maybe you could use some spare time to push it further?

Being able to skip the messy sealant would be a nice feature in my book!

 

[SuboptimusPrime]

I was talking to @jackalope during a ride yesterday and wondered why not just add the rim protecting, damping stuff to the inside of the tire? Obvious drawbacks are that the material would need to be way cheaper since tires don't last as long as a CC or HN. Wonder about some type of rubber bumper type deal...

 

[mtg]

I was talking to @jackalope during a ride yesterday and wondered why not just add the rim protecting, damping stuff to the inside of the tire? Obvious drawbacks are that the material would need to be way cheaper since tires don't last as long as a CC or HN. Wonder about some type of rubber bumper type deal...

I've thought about that as well. Maxxis Double Down tires have a 2-3mm thick rubber piece in the sidewall for that purpose. My experience says it helps to prevent the tire from being sliced in a pinch flat, but has none of the other benefits.
Another challenge is rolling resistance. If the foam is in the tire, it would likely be difficult for it to not add resistance.

 

[slimshady]

How about making a "semi tubular" tire? Why not just put the HN insert in (for pinch flat protection) and glue together half of the inner tube to the tire itself, that would prevent burping?

View attachment 125992

I'd say we are halfway there with the Innova idea:

https://m.pinkbike.com/news/innova-itt-tubeless-tires-taipei-cycle-show.html

We're missing the inner insert and some decent compound and pattern though.

 

[SylentK]

If it weren't for cacti, thorns and other rather sharp shit found naturally occurring in my riding "zone"...I'd probably be on tubes. I guess you don't need that kind of protection? Then I don't really see why your proposal wouldn't work. Go for it.

 

[kidwoo]

I just finished a 4 hour enduro (yeah @kidwoo I know you love them)

I enduro so hard I filet my tubes open, sew them back up with huck norris on the inside, put 1 liter of sealant in through the valve hole, then put cushcore on top of a schwalbe procore which sits on a slit road bike tire, and then rivet it all into a rim before I put my 400g 3.0 tire on. I think it shows some promise. Tubeless is just so difficult and complicated.

 

[Jm_]

I enduro so hard I filet my tubes open, sew them back up with huck norris on the inside, put 1 liter of sealant in through the valve hole, then put cushcore on top of a schwalbe procore which sits on a slit road bike tire, and then rivet it all into a rim before I put my 400g 3.0 tire on. I think it shows some promise Tubeless is just so difficult and complicated.

Don't forget running a tire inside of a tire.

 

[kidwoo]

Come on, don't you think that's a little excessive?

 

[Gary]

View attachment 125992

Never understood why this isn't how all tubeless tyres are made.

 

[Gary]

Don't forget running a tire inside of a tire.

Ah... the good old days

 

[SuboptimusPrime]

I've thought about that as well. Maxxis Double Down tires have a 2-3mm thick rubber piece in the sidewall for that purpose. My experience says it helps to prevent the tire from being sliced in a pinch flat, but has none of the other benefits.
Another challenge is rolling resistance. If the foam is in the tire, it would likely be difficult for it to not add resistance.

I hear you--guess I was thinking something on the inside surface of the tread, not the sidewall. As you say, may affect rolling resistance as well as the ability of the tire to conform to terrain.

 

[bagtagley]

I've had a horrible season for flatting. My riding gear and shed have signs of sealant explosions splattered across them. This after several years of relatively little fuss. I now despise sealant, but slightly less than I despise tubes. I hope that an ultimate, sealant and tube free solution comes along. Until then, I'll continue to pack a poncho and some baby wipes.

@mtg if I'm going to choose one, do you recommend DD or EXO + Huck Norris?

 

[mtg]

I've had a horrible season for flatting. My riding gear and shed have signs of sealant explosions splattered across them. This after several years of relatively little fuss. I now despise sealant, but slightly less than I despise tubes. I hope that an ultimate, sealant and tube free solution comes along. Until then, I'll continue to pack a poncho and some baby wipes.

@mtg if I'm going to choose one, do you recommend DD or EXO + Huck Norris?

How are you flatting? Slicing tires or snake biting them?

If slicing/puncturing tread, DD.

If snake biting/rim smashing, EXO with HN

 

[bagtagley]

Snake bites. Thanks, gonna give HN a shot.

 

[Udi]

I just want to say I appreciate the serious and long responses from everyone!

Being able to skip the messy sealant would be a nice feature in my book!

This!

@toodles
Regarding cc with a tube, since it is closed cell foam, the pressure from inflating with or without a tube will compress it.

@toodles
This. I think Westy edited his post to reflect the same point.

Might be as simple as cutting a hole in the liner and finding a tube with a long enough stem to reach through. As the tube has to take up less space you could get away with a smaller size than would be normally required for the size of tire.

Yes! I'll have to see what's on offer, but hopefully using a much lighter tube proportional to the remaining volume left (varying depending on insert) won't actually render much/any loss in durability since the tube won't have to stretch as much. Hopefully even if it's a bit thinner, the pinch resistance from the foam will outweigh it.

Good point on needing a real long stem too, didn't think that far ahead but have made a mental note. It really makes me happy that the one person ripping on me the most in the other thread has been thinking of the exact same thing I have.

Or better yet, convince someone else to try it.

So I had this real good idea and tried it out (it was excellent) - would you mind verifying it?

- Now, I've run Huck Norris with a tube. I put the foam insert between the tube and the tread. It felt weird

Why'd you put the insert between the tube and the tread, to stop punctures reaching the tube?
It needs to go between the tube and the rim to cushion the blows on (and from, in my case) the rim, or at least that's definitely the only way I'll get any benefit out of it.

As for the sealant thing, I should have probably mentioned that most of my holiday-housemates are faster than me, and about half of them race WC level DH. Not top 10 but hard enough to blow shit up spectacularly, I don't think most failures were setup related. The few bikes in the household with tubes were the ones with least problems in that area over the season, which I don't think was a coincidence. The other thing was that when tubeless failed, bikes got left unridden for weeks, wheels stolen from others, etc. No one likes fixing that crap.

My personal goal is only to get more grip so i can keep up without riding outside my safety margin as much, but more importantly to have less failures (and limit annoyance when failures do happen). I'm in this for fun and the bottom line is that tubeless sealant / goop saps fun. Everything from the slow leaks to the mess to the annoyance when travelling (bike has to go on plane, sometimes forced to deflate). I've never had problems with actual punctures or sidewall cuts BUT I've always run tubes, so if I switched to sealant this could become a real pain (it certainly seems to be for many people running tubeless!) - so again - this is a new problem I don't need. With tubes (perhaps by chance) often small-to-medium casing damage that would cause a leak with tubeless is a complete non-issue and I like that. Rim dents are hard to avoid too, so I'd like my solution to handle that.

FYI I'm running FR570 rims, and MM SuperGravity rubber. I should be running DH casings, this is partly the reason I have (any) problem in the first place - but my ONLY mode of failure is pinch flat, so I don't need the dead weight of a wire bead or any increase in pin-puncture / torn carcass protection. Basically my thoughts are instead of switching back to DH casings, I can target my problem more efficiently and get more grip at less weight with a creative solution. Just not sure what the best one is.

Heavy bikes (for me) sap fun too - so what I really want is to get more traction and reduce flats while adding little to no weight over my current setup, and keeping failure mode non-messy. I understand this is a tall order and may not be possible, but perhaps with the new tech there's something I can try.

Now I do understand that what I want isn't what you need/want so I'm definitely not saying this is something you/others should do - but I've listed what I want in the OP and apart from the bold text, I want a clean, hassle-free solution. I do believe that CC and sealant alone is probably a pretty good solution (buckoW rocks it on his DH bike and likes it a lot) but he also has his workshop near where he rides, whereas on my trips I'm lucky to have a broken lever and a floor pump that works. I can't take much on the plane so I'm left at the mercy of whatever makeshift tools are at the holiday house.

Now to me, huck norris looks like a terrible design compared to CC, I don't like the outer profile of it being jagged (as it means some parts provide less pinch resistance), and the fact that it doesn't even remotely match the profile of the rim. But on the other hand the tailored CC is expensive, heavy, and doesn't leave much room for a tube. I think what would be ideal for my experiment is CC at 2/3 of the thickness, perhaps with the outer central recess deeper. With the CC I'd also be using a very light tube (like 100g) and I'm not sure how that'd go, but I think it'd probably be okay since the limited volume means the wall thickness of the tube would stay fairly thick. That still leaves the concern that it might be (very?) hard to assemble, thus breaks the fun rule if the tube fails? I've vaguely thought about modifying a CC (to scoop a bit out of that recess all round, but no idea how to do it neatly), and I've also wondered if the system would still hold air if the tube got damaged? That could be cool.

Not having a go at you at all here btw - just wanted to share my specific use case in case anyone has any ideas. This is strictly for DH. I think for trailbikes the sealant makes more sense because you are often running thinner casings which are vulnerable to being physically punctured. You might think you can "get away with EXO" after adding CC to your trailbike, but really, you don't have a choice because 2.3 DD (1050g) + CC (250g) + sealant (~120g) would make your wheels WAY heavy for a trailbike - thus you are FORCED to run EXO, thus you are essentially FORCED to run sealant to deal with the thinner casing vulnerability.

I'm not saying this is bad at all - I think your "final" setup is probably the best Enduro setup for ultimate grip with good reliability and decent overall weight, but for a myriad of reasons (hopefully now clear) it's very far from the solution for me.

How about making a "semi tubular" tire? Why not just put the HN insert in (for pinch flat protection) and glue together half of the inner tube to the tire itself, that would prevent burping?

Why is burping a problem though, the air is sealed inside the tube like a normal tubed setup?
I did think about gluing HN to a tube though, and then straight after that (since I don't really like the HN design), I thought why couldn't I just get my own appropriate damping foam and glue it to the rim-side half of the tube.

If it's light and works, I just pack a couple extra foams and glue for if/when I get a flat - and if I run out then it's no fuss to just run a regular tube.

My question then was what glue would I use, would plain CA work? It dries quite stiff. Not sure rubber cement is the right thing either though.

If it weren't for cacti, thorns and other rather sharp shit found naturally occurring in my riding "zone"...I'd probably be on tubes. I guess you don't need that kind of protection? Then I don't really see why your proposal wouldn't work. Go for it.

Yes, exactly!
This is for DH, and I'm using SG casings (pretty close to a DH casing), so it's probably that combined with not riding in areas with natural killers like you have, plus the fact that occasionally the casing will get damaged but not the tube and thus there is no failure.

My failures are 100% pinchflats, and most of the time I know exactly when I do it (before the whoosh). Watch me cop a superthorn as soon as I try this though.

It's good to hear it said/verified anyway, because I posted this thread thinking "why do I need to create new problems by fixing a problem I don't actually have?".

 

[Jm_]

Foes Mutz. You're welcome.

 

[toodles]

Expensive experiment - but if you could get a cush core liner, I wonder if you could get a wad or leather punch and remove some material from the centre all the way around to trim excess weight from a place it is less needed?

 

[troy]

Why is burping a problem though, the air is sealed inside the tube like a normal tubed setup?
I did think about gluing HN to a tube though, and then straight after that (since I don't really like the HN design), I thought why couldn't I just get my own appropriate damping foam and glue it to the rim-side half of the tube.

If it's light and works, I just pack a couple extra foams and glue for if/when I get a flat - and if I run out then it's no fuss to just run a regular tube.

My question then was what glue would I use, would plain CA work? It dries quite stiff. Not sure rubber cement is the right thing either though.

As I have no clue what are You trying to say, I will try to explain my idea.

Tubeless setup suffers from burping and doesn't work with dented rims. At the same time, using lighter tires usually ends up with a cut casing. Therefore, if You glue the bottom half of the tube (part with the valve) to the tire, You would enclose the system and burping/damaged rim wouldn't be an issue anymore.

You can use 3M primerless urethane glue for car windows. It is designed to keep the glass glued in to a vehicle under extreme forces created by collision, it is super strong, but as it is designed to set up in almost any environment so it is difficult to keep a tube around after you open it. I think, You can use some kind of vulcanizing glue as well. Sanding the glued parts with some rough sandpaper will help with the adhesion of both parts.

HN insert should cover the pinch-flatting problems.

I'm not sure why do You wanna glue the HN to the inner tube. I think You can glue some foam strips to the tire area directly above the rim sidewalls to cut some weight, but it sounds like shitload of work to drop 20g out of a 70-90g insert.

 

[landcruiser]

@Udi it sounds like you really just want to track down some of the few remaining UST tires. Those things still mount up tubeless, but don't need sealant to hold air. UST plus CC (or equivalent) would have all the attributes of the system you are describing, but without the "mess" of sealant or the burden of trying to fit in a tube around any of the foam inserts.

I don't know where to find a UST tire with a tread pattern that's worth a damn anymore though... edit: apparently 26x2.5 Minion DHF UST's are still around

As per some of the the other ideas floating around in this thread. Any foam or inserts of any kind should always be placed as close to the rim as possible. The only two reasons to use an insert are pinch protection and sidewall stability, both of which start at the rim. Throwing the insert to the outside of the tire is going to be less effective while driving up your rolling resistance.

 

[Gary]

It needs to go between the tube and the rim to cushion the blows on (and from, in my case) the rim, or at least that's definitely the only way I'll get any benefit out of it.

Think about how a tube pinches. a foam insert between the rim and tube will help. but won't eliminate pinch flats.
Higher tyre pressures could though.

Good point on needing a real long stem too, didn't think that far ahead but have made a mental note.

valve extenders for road deep section rims come in various lengths.

My goals are to run less pressure, get less flats,

What do you weigh? what pressures are you running? and why do you want to go lower?

 

[mtg]

@Udi It sounds like the ideal setup for you would be to keep the tubes and go up slightly in tire volume, and down in tire pressure by 0.5 - 1psi. That would make for more grip, and keep your rims further from the rocks.
I'm not sure what tires you're using now, but if 2.35", maybe try some true 2.5" in DoubleDown or Super Gravity.

 

[Udi]

Nah I'd like to see what the wank-foam has to offer in terms of damping, and I'd like to see how much extra protection it affords the tube. I feel like the answer might be "a lot" if the implementation is right. I'm on 2.35 Magic Mary (slightly bigger than Maxxis 2.5) and any bigger than 2.35 in Schwalbe is huge.

I just don't want the stupid goo.
@landcruiser nailed it on all counts, unfortunately those solutions aren't viable + I really like the MM.

I'll have a think about it and try something.
Hopefully everyone understands what I want now.

As I have no clue what are You trying to say

Have you tried reading the thread title where it says "instead of tubeless"?

Anyway, read landcruiser's post if still confused. Westy and SylentK both got it too.
Those three posts together explain all.

 

[troy]

Have you tried reading the thread title where it says "instead of tubeless"?

But there is a tube in there, just cut in half and glued to the tire... so it is not tubeless, but more like a tubular tire Anyway, source of Your problems are tubes, so IDK why You want to stick with them so badly, especially with Your concerns about the weight.

 

[iRider]

Just wondering if anybody can remember those Panaracer Shield DH rims that had this plastic tube in the rim bed to protect the rim and keep the tire on? I always wondered if something like this together with an UST rim and tire would solve many problems. Rim protection, no burping because of UST and the plastic tube keeping the tire on, no need for sealant.

THE tried something along these lines as well with their Eliminator rim ( https://www.pinkbike.com/news/THE-Eliminator-rim.html ) but used it with tubes.

For me the only problem with a full UST system is that after a small burp your tire pressure is lower, causing you to pinch flat the tire on the next big hit and poke holes in it, rendering it useless. That plastic tube in the rim bed would solve this by stopping the pinch flatting and the burping.

 

[Udi]

But there is a tube in there, just cut in half and glued to the tire... so it is not tubeless, but more like a tubular tire Anyway, source of Your problems are tubes, so IDK why You want to stick with them so badly, especially with Your concerns about the weight.

For a smart dude you are really struggling with this one. I think it stems from not actually reading everything I said - you're assuming many generic problems are mine, they are not.

My source of problems aren't directly tubes, or at least to remove them (in their complete and closed form) would create new problems that are much worse for me. It would be better (in my case) to reduce the drawbacks of tubes while keeping their benefits, rather than to create new problems I can't easily fix - particularly ones to do with mess / hassle (especially after failures), as I explained pretty clearly.

 

[profro]

I've had a horrible season for flatting. My riding gear and shed have signs of sealant explosions splattered across them. This after several years of relatively little fuss. I now despise sealant, but slightly less than I despise tubes. I hope that an ultimate, sealant and tube free solution comes along. Until then, I'll continue to pack a poncho and some baby wipes.

@mtg if I'm going to choose one, do you recommend DD or EXO + Huck Norris?

I am right there with you. IMO, I think its some combination of wider rims and modern "tubeless" tires. I am over this as well. I don't often agree with Richie Cunnigham, but this time he is spot on.

 

[Udi]

UST plus CC (or equivalent) would have all the attributes of the system you are describing, but without the "mess" of sealant or the burden of trying to fit in a tube around any of the foam inserts.
I don't know where to find a UST tire with a tread pattern that's worth a damn anymore though

Yeah unfortunately I'm on 650b, and probably won't consider changing the rims and pattern I'm very happy with (DT FR570 / Magic Mary) - but I'm glad you understood exactly what I wanted if nothing else.

Do you think fitting the tube in would be a big hassle, and do you think there would be an increase in likelihood of tube failure if a much lighter one was used proportional to the remaining volume with CC fitted? I'm currently running a 310g Maxxis Freeride tube, for the weights to be OK, I'd need to drop to something like 100g which is obviously much smaller. The inflated wall thickness probably won't be hugely thinner due to the smaller volume - but no doubt still thinner. I'm going to look myself soon, but if you have any tube recommendations for this application I'm all ears.

I think you will have a better guess than me at how much protection the foam would "add" to the tube, and if the tube's new profile (probably being "flattened" a lot more often) would cause any additional concerns? I currently only flat if I hard-bottom against the rim.

Appreciate your thoughts.
Your solution would certainly be the ideal one (if modern parts existed) - although if the tube will work, it also mitigates problems with minor casing damage, which avoids creating a new problem. I think the parts currently exist to try my idea, but I suspect you'll have a far better idea of how well it'll work and how difficult it'll be to assemble.

I don't often agree with Richie Cunnigham, but this time he is spot on.

Totally, same here.
Not bothered what his motivation was, I'm glad someone said it - hopefully it will generate some positive changes and new designs in the future. This is one area where we need a much more integrated solution.

 

[Westy]

I enduro so hard I filet my tubes open, sew them back up with huck norris on the inside, put 1 liter of sealant in through the valve hole, then put cushcore on top of a schwalbe procore which sits on a slit road bike tire, and then rivet it all into a rim before I put my 400g 3.0 tire on. I think it shows some promise. Tubeless is just so difficult and complicated.

I think it would be easier to run redundant wheels.

 

[Udi]

They won't be redundant when I'm upside down!

 

[landcruiser]

Do you think fitting the tube in would be a big hassle, and do you think there would be an increase in likelihood of tube failure if a much lighter one was used proportional to the remaining volume with CC fitted? I'm currently running a 310g Maxxis Freeride tube, for the weights to be OK, I'd need to drop to something like 100g which is obviously much smaller. The inflated wall thickness probably won't be hugely thinner due to the smaller volume - but no doubt still thinner. I'm going to look myself soon, but if you have any tube recommendations for this application I'm all ears.

I think you will have a better guess than me at how much protection the foam would "add" to the tube, and if the tube's new profile (probably being "flattened" a lot more often) would cause any additional concerns? I currently only flat if I hard-bottom against the rim.

Disclaimer: I like sealant.

That said, the setup you want doesn't sound impossible to execute. I don't know the exact specs of crush core (CC), but I would start with the assumption that a 27.5" CC will have the similar effective outer diameter as a 29" wheel, so I'd be looking for a low volume 29er (or larger 700c cyclocross/hybrid size). I'd look for a tube that has a replaceable presta valve so I could use an extender like Silca that moves the valve back outside of the rim (not the universal ones like Zipp makes). Punch a hole in CC for the valve... Then depending on how tightly the tube fits to crush core, I'd try to wrap it onto the CC and hope that it's just snug enough to stay put without adding any constrictive forces to the CC. Then install CC per instructions, with the tube already in place.

One problem you're going to have is getting enough even force on the tire to seat the bead before the CC starts locking it down. Soapy water or something similar will probably be your friend (so much for less mess). You also might end up with some funky tire shaping. A tubeless setup with CC will still have more uniform pressure across the entire tire to drive shape. A tube with CC will have the tube pressurizing the top half, and then pressing CC downwards into the lower part of the tire. Could do some weird things depending on how closely the CC matches the natural shape of the tire.

I wouldn't be worried the cavity being an odd shape for the tube. Tubes are pretty good at conforming to weird shapes. If I had a CC to play with I could give a better estimate of tube size to start with, but it shouldn't be hard to figure out once you get it.

 

[toodles]

A couple of tube manufacturers do offer stupidly long valve stems as well which might let you get away without running a valve extender.

In the past I've ripped valves off tubes by running low pressures and having the rim 'slip' or rotate inside the tyre under prolonged braking causing the valve to end up angled before finally tearing. The system you're looking at running might be less likely to do this or more likely, but worth keeping an eye on at first. Shouldn't be a problem with Formula brakes as they're too piss-weak to make the tyre slip but if you end up running Trickstuffs it will probably happen first time you skid.

 

[Happymtb.fr]

Riding your bike in figure of 8 with slightly over pressurised tyres might help to seat the tires properly.

 

[iRider]

@Udi : Why don't you try it the other way around? Instead of using a tube, try to pre-treat Magic Marys so that they hold air without sealant? Kind of like impregnating fabric. @landcruiser might have an idea what to use. Then you could run the tire tubeless with CC w/o goo. Should be pretty lightweight as well.