Something I’ve never seen before from Keegan and Tobin at Unbound on Saturday - Each of their wheels had 2 valves. Supposedly, one valve was the normal tubeless valve and the other was the valve stem for an uninflated tube ready for action in case of emergency.
Pretty interesting concept in my opinion. For a race like Unbound with high risk of flats and the value of fast tire fixes, I think this makes sense. It’s probably a pretty rare situation where you’d go to the tube inflation, but in those rare situations you could be back in running in under a minute rather than 5+ minutes pulling the tire and putting a tube in. You’re already carrying at least one backup tube at Unbound, so the weight penalty is insignificant even if you are adding a 2nd tube (which many carry anyway).
The place it wouldn’t work great is a big slash that still requires a boot. At that point, you are breaking the tire bead anyway to put in a boot, but having the tube already in the tire could be a significant time saver there as well. The only really big downside I see is if you mangle your tire back enough to damage the tube as well (I could see that with a major rock strike/pinch).
Anyways, I think the idea has legs. Will be interesting to see if it becomes a thing for gravel and even marathon MTB. Maybe it’s been done before, I’ve just never seen it. I do wonder how they sealed the tube’s valve stem inside the rim to prevent leaks. It wouldn’t be that hard with a purpose-built stem/tube designed to operate this way, but I assume they had to hack something up to make it seal properly from the inside.
I could see tubes in the future being designed specifically for this use case that are more snug-fitting on the rim to stay out of the way of the sealant. They could use rubber on the valve to create a seal like tubeless valves, too.
Yeah, it might have been as simple as ripping that angled rubber grommet off a standard tubeless valve stem and putting it on the tube’s valve stem. Or maybe they found an appropriate sized o-ring that worked well enough. Ideally, the tube would be designed for it with some “backer” area to compress the grommet/o-ring. Some of those lightweight tubes have a little beefed up section around the valve, maybe that’s enough for proper compression. I assume they tested this quite a bit before running it at their biggest race of the year, so clearly they came up with something that worked. I’m just curious if this is something they totally hacked themselves or if there is some industry help going on with a special tube or parts involved.
Agree, something like a mix of cushcore and tube - a foam insert with a tube inside. In case of a flat, you can pump it up and add some volume to the insert. On the other hand, the tube would be protected from pinch punctures.
With a normal tube, I’m wondering if it doesn’t get in the way of the tubeless valve, blocking the airflow, especially when trying to reduce pressure.
And as mentioned in the other thread, you really have to be careful with dynaplugs and the likes, and thorns in the tyre, if you want to use that tube.
Agreed, but those are issues anytime you use a tube anyway, so I consider those a wash. I don’t think you are going to damage an uninflated tube with a dynaplug or thorn going through. I guess maybe if you are running it along with an insert (or something to push the tube against the tire), but I don’t see this as a solution to run with inserts unless it’s some kind of fancy insert/tube combo as referenced above.
And sorry, I didn’t see a post on this already (and I actually looked because I thought it was come up). Hopefully a mod will merge if this is a repeat.
Yeah, I saw this and I thought it was kind of interesting, but as @eddie mentioned, I also saw that they had drilled the extra holes in the rims themselves. I’m not sure how that would render the mechanical integrity of the rims…
BUT… I was hoping someone would bring this up because I could have SWORN I saw something at one point in the last few months about some sort of weird double-valve, one for inflating a tube and one for putting sealant into the tire. Maybe something I saw on a Sea Otter video? So the concept there was you pre-insert the tube into your tire, and then use the one for sealant and then inflate the tube in case of emergency. But I could have completely dreamed this whole thing.
As others mentioned, though, I don’t know how this could work with an insert. Do people ride gravel with inserts? I thought that was primarily a mtn biking thing…?
I honestly wouldn’t worry about that. Holes in that part of the rim are fine. There shouldn’t be any difference between the new valve hole, and the original one. (Unless they messed up drilling, but it doesn’t sound particularly difficult).
Some definitively do. It’s a trade-off between added rolling resistance, and puncture protection. Whatever seems more important, I guess.
You already have to carry at least one tube when racing gravel or marathon MTB (or often risk walking for 20+ miles). So, it’s always tubeless with tubes. I think of it more as an question of where do you want to store your spare tube(s). Storing them in the tires could be dramatically better in certain race situations.
I don’t know if I’d keep the uninflated tube in the tire for training/riding around, seems like it would be a mess to deal with when swapping tires. But maybe not that big of a deal. Honestly, just having one less bulky thing in downtube storage or saddle bag is a win in my opinion. For me, the big question for non-race situations might be whether I run them in both tires or just in the rear. I seldom flat in the front and have never had to put a tube in the front (knock on wood). I guess worst case if only running a rear tube and having a bad front flat, you pull the tube out of the rear and put it in the front. You could probably ride for 10 years without running into that situation on a training bike and it wouldn’t be the end of the world.
If I were a rim manufacture, I think I’d start doing 2 valve holes in rims going forward and shipping them with a removeable plug. What’s the downside? I’m sure the weight wennies will balk and talk about rotation mass increase, but it’s not mandatory. Maybe I’m missing something obvious, but this is seems like a really simple/smart thing to do in some situations. I’m not really to drill my carbon rims today, but I’ll be watching to see where this goes and probably be an early adopter if it shows promise.
No. This is inaccurate and really weird mansplaining at the same time ( I am well aware that we carry tubes on our person. This is a cyclist forum). Tubeless, as marketed and designed, is supposed to replace tubes inside the tire. Hence the name, tubeless. Adding a tube back in makes this no longer “tubeless”. Its “tubeless plus” (?).
I think it was just his way of saying even though tubeless is our first choice the noble tube always has a place.
But now I’m thinking if they’re going to have a tube already installed in the wheel for emergency quick fixes why not develop some sort of emergency pull-string-to-inflate inner tubes similar those auto inflating life preservers? No pump or Co2 needed, just pull the cord and get back to it.
Forrest for the trees my friend. I don’t know how you’d see that as “mansplaining”, but I’m just trying to make the point that you need tubes (or at least a single tube) on the bike when running a tubeless system, it’s just a question of where you are storing it. I don’t see any significant downside to storing it in the tire uninflated. I’d still say I’m running a tubeless setup with an uninflated tube in the wheel, but I could see how someone might call it something else. It’s clearly not a traditional tubless setup and not a traditional tube setup.
Seems like a good application for PU tubes. Lightweight and hug a 29" rim bed pretty snugly. it would be kind of a mess when the time comes to change a tire.
They were all worried about mud clearance. Keegan has been running a suspension fork, but pulled it off to get more tire clearance. The sticky mud was a non-factor, but nobody knew that going in and a bunch of people ran smaller tires than they would have.
