29 inner tube on a 36

Hi
Probably loads of threads on this but can’t seem to find any that really answer my question.
I have a Nextie carbon rim 36” it’s a deep rim. The presta valve 40mm only just comes though.
Can anyone recommend inner tubes with a longer valve that I can use on my 36 rim.

Also 29” inner tubes that have been fitted to a 36” rim

As an alternative, I’ve seen presta extenders at some LBS in Canada as well.

I’d just go to my lbs. They should have what you’re looking for and they need the business. It may cost 50% more, but you’ll get the right product and help a local business.

After reading @Hammer post in the carbon rim thread about the tube he used with the valve stem being a little short I went with a 42 mm valve stem MTB tube for around $7 usd

It installed very easily and so far is riding perfectly

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This is the best picture I have right now of what the 42 mm valve stem looks like. Gives you plenty to get the pump on but I wouldn’t want it to be any less

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I was looking at the conti tubes, i went to my LBS and got a SV19. It works but it’s very close with the pump though. Going to order a conti tube for a spare.
How did you find getting the nightrider tyre on!

image|640x480

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looks great with the triton frame! The tire was a breeze to install. I did use one tire lever as an aid but I could have done without the lever with a little more effort

Thanks. Went out on it this morning and it’s like riding my 29er. The whole uni only weighs 6.6kg which is light for a 36er.

Did you put your inner tube on first and then the tyre?
I put my tyre on first half of it and then stretched the tube onto the rim and then the other side of the tyre.

I put one bead of the tire on and then inflated the tube a little so it held a round shape and I didn’t have to worry about getting twists in it. Once on i deflated the tube and worked the other half of the tire on.

Inflating the tube some before you install it is a big help

While
this is probably 100% my fault I feel the need to show it since I recommended this tube

The tire was pressured up to around 45 psi and strapped tight over the tire in two places in the hot sun for at least an hour and a half. The tube ruptured near the valve stem which was almost opposite of where I had the tire strapped. Like I said probably 100% my fault but just FYI when dealing with these 29’er tubes stretched over a 36 rim

Ouch, did it do any other damage. I’m running my at 35psi and so far so good, although over in the uk we probably don’t reach the kind of temperatures you do.
I’m using a Schwalbe 29x2.5 inner tube, I’m guessing around the valve area is going to be the weak spot.
@rogeratunicycledotcom is there anyway of coming up with a 36” tube with a presta valve?

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Sorry no plans to do Presta valve for the 36" for next few productions.

I generally avoid the Schwalb and Continental innertubes for conversion to 36". They do not stretch in the way the Kenda one does.

I do not believe this failure is not 100% caused by the inner tube though although may be a contributing factor as the Schwalb inner tube is not stretching universally. The rim is a tubeless rim without a hook and the 36" tyres are not designed for this style of fitting and is the main problem. I need to get my hands on the rim and double check this. Fitting these tyres on to hookless rims is possible, but getting them seated evenly is critical and should be done very carefully.

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Could the heat have something to do with it @WeaponizedBacon is in the USA i believe.

On the carbon rim on UDC is that a hookless rim @rogeratunicycledotcom

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Heat will have emphasised the problem.

Yes the Braus rim is also hookless.

So it could be combination of the heat, inner tube, and the tyre not being hookless compatible.
Thanks for the input especially on a Sunday.
Is there any plans to make a 36” tyre suitable for these hookless rims?

Is there any plans to make a 36” tyre suitable for these hookless rims?

This seems like a situation where if all current tyres are compatible with the current Stealth rims, then it’s surely a dimensional problem with the carbon rims if they’re not really compatible. AFAIK there’s not much of a manufacturing difference between hookless compatible tyres and non-hookless compatible ones.

Not sure what temperature you pumped it up at, but in the sun it was probably more like 50-55PSI, plus whatever the straps added.

What are your plans now? Run a 36" tube, or try a Kenda one?

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oh, this is not a simple answer I am afraid and I am going to be a bit vague. The problem is the tubeless standard(s)… yes there are 3 of them! Tyres and rims work with ERTO. This is a figure that is the inside of the tyre bead and the outside of the rim. Tyre stretch and need to fit on to the rim that does not. Traditionally there is about +1mm between the tyre and rim. The distance from the ERTO surface on the rim to the outside of the rim is traditionally 7mm, this allows the tyre to fit over it and holds the tyre in place. One of the expensive tools for rims is the one used for cutting the rims. This is like a big steel drum. Its inside dimension is ERTO + 2*7mm+cutting blade thickness.

Then come along the tubeless tyres. These require a compression fit, so the tolerance is about -2mm. So… there are 3 ways to make them work:
You can either make the ERTO of the rim bigger or the tyre smaller.
If the tyre is made smaller then it wont fit on non tubeless rims as they don’t have the smooth ramp to get the tyre seated.
If the rim is made bigger to fit the tyre at -2mm then it wont fit in the cutting drum… now you get to the fun bit, the solution that quite a few manufactures do is they increase the ERTO but leave the outside the same size, so the lip is only 5mm! Yes this works… mostly, but I am guessing you can see what happens here.
Another solution is you make both rim and tyre bespoke and you see this with tubeless only rims and tyres.
Carbon rims can do this, but… they can’t do hooks so they make hookless. This again works mostly. The problem is that the rim can not be too big or you can not get your tyres on, so they tend to be only just big enough and I suspect they are made around 27.5 rims where they work really well. On 29" they work, mostly but have more problems.
The 36" version should work as they can make the rims to fit the tyres, but there is a problem in the tyres are not made by a process used by most modern tyres, so they have a bulky bead and require to be held in more than modern flexible beads, so they are not made at -2 but at 0.
All in all… no easy solution. Just be careful when you put your tyres on rims for the first time.

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no damage! It just blew the bead off the one side.

@mowcius i will likely try a Kenda tube. I would happily run a 36” tube if a presta version were available. I have drilled aluminum presta rims for shrader valves so i may consider that route if its ok to do with carbon

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I think I’d use a dremel tool rather than a drill for that job.

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good idea!