I have heard of using a 29" on a 36" and was wondering if anybody was running a 26" tube on their 29er. I can’t find a 29" tube with a Schrader valve and I don’t like Presta valves–so I was thinking of getting the very-available 26" tube to put on my KH-29FR. Anybody done it?
Carey
I haven’t done it personally (although I do use 29er tubes in my 36), but it’s less of a stretch than 29 into 36, so I’m sure it would work fine. Just need to be a bit more careful when fitting it to avoid pinching when the tyre goes on - a little bit of air in the tube while fitting the tyre helps.
Weird that you can’t find a Schrader valved 29er tube though - especially when the USA seems so anti-Presta.
Rob
Yup, been running my KH 29er with a 26" DH tube (Nokian) for a while now, swapped out a 1/2 dozen tires, no problems at all. I also found it was impossible to find a decent 29er tube, so stretching a super stout 26er tube was the best bet.
It’s kind of a pain to get the tire on without pinching the tube, but if tyou take your time it’s no problem. It does make the tire feel more solid if you use a burlier tube, which is a nice thing since most 29er tires are wimpy 
I run a Shwalbe Racing Ralph 2.4
I haven’t tried this yet but when the tube goes in the 29" it will be getting a 26" tube as they are easier to get hold of and lighter.
i run this too. try and get the beefiest 26 tube you can. one tip i saw was to inflate the tube on its own a day before you put it on the rim to let it stretch a bit
Yes. Not had any problems. A 24 will also work.
While I can see some weight savings using a 29er tube in a 36er, the savings would be almost negligible it would seem, using a 26er tube for a 29er. At least for a KH 20er, which is feather light as it as! But for me, a little weight savings isn’t worth having a potentially premature and possibly abrupt, catastrophic blowout, especially at speed! The more you stretch an inner tube, the thinner and weaker it becomes. 
I’ve put a standard 26" tube into a 24x3 tire and it works very well. I don’t see why putting it in a 29 would be much problem. Blowouts happen because the tire allows a small area of the tube to take more volume than the area around it. This can be because of a weakness in the sidewall, or because the bead isn’t seated correctly. Using a smaller tube than what is called for increases the chances of the tire being seated on the tube rather than the rim which can cause a blowout. As long as you take care to make sure that the tube sits entirely inside the tire before you bring it up to pressure the chances of a blowout are the same as with any other tube.
If I needed to I wouldn’t hesitate to run a 26" tube in a 29er. Another benefit aside from getting a Schrader valve is the ability to get a replacement tube at any hardware store. 29er tubes are still a specialty item, but maybe some day they will be ubiquitous.
Thanks
I NEVER understood why anyone would take that kind of risk for so little savings in weight! Your opinion [once again] has been very useful to me. 
It’s scary!
40,000 unicycle miles with no riding blow outs. Lots of risk. It really is scary! Just be safe, play safe, ride safe, don’t get hurt!
Ive been riding my 29 with a 26 tube with presta valve for most of the year now. Simply because my 29tube ripped at the valve and I had a thin bike tube handy which i put in so i could ride the next day. I thought it wouldnt last long but its still going strong so i’l keep it in till it goes bust.
Yep, had to do it once when we had a puncture in the middle of nowhere, and the only spares available was a 26".
It works fine, and is less of a stretch than using a 29’er tube in a 36", which many people do.
My Coker 36" is running with a 26" DH tube!!! (yes, yes!)
(I admit I had to invoke the 10000 names of god to let it fit but apparentely this was an efficient method )
Go one better and go tubeless. A pot of stans only costs $10, and with about 50c worth of good duct tape you can get rid of the tube all together. The goo will fix small punctures on the fly and you save a considerable amount of rotational weight too.
I see some people scoffing about people ‘risking’ blowouts to save minuscule amounts of weight. I’m sure if they actually tried riding on a tubeless set up (for a considerable amount of time or for longer distances) their legs would inform them of the merit.
mark
Anybody use a 26"tube on a 29" wheel?
We’ve done for some time now, with the 40,000 unicycle miles that have been put on and NO BLOW OUTS! Found out that it’s just more economical to use the 26" tube. If you get into a tight spot you can purchase a 26" in just about any store in the USA that you want. One of the Mountain rides that Bungeejoe did he had a FLAT and needed a tube and we found in the local Rite Aid Drug Store carried tubes and other bike equipment. The cost of the tube was only $2.99:D Beats the heck out of $10.00-30.00. 
My question had nothing to do with saving a few ounces of weight by running a smaller tube. It was about being able to find a tube that uses Schrader valves versus a Presta valve which is all I can find in a 29" tube.
Just wanted to know if anybody was doing it, and clearly several people are. I have little fear of blowing out the tire because I do not run the pressure that high and I don’t do drops higher than a curb. Thanks for the responses.
Carey
The 26" tube went on the rim perfectly. I did not even have to stretch it at all. This is what I will plan to use from now on.
Carey
I have a nimbus touring 29er and a kh29 muni. I have been running 26" tubes in both for as long as I’ve had them with no problems at all. The only thing is to be careful that the tube isn’t in the way of the tire bead when seating the tire on the rim.
Its the tire that keeps the shape for the tube. If the tire doesn’t contain it properly a blowout results regardless of tube size. Thicker tubes only help to prevent punctures.
They actually add significant structure which makes the sidewall firmer, which is why I use one with my soft sided RR 2.4
I also found that the DH 26" tubes work great for the Larry 3.8, which means all of the unis run the same tube except for the 36, but I think that ones gonna tubeless soon
I hadn’t considered that actually. I never ride big soft bouncy tires with low pressure so I never had an issue but I should try it sometime.