Anyone tried a 29er tube in a Coker?

More last minute woes,

My Stans no tubes kit arrived a couple of weeks ago- but they sent the wrong inner strip- instead of sending a 36" they sent a 26". So I had to wait and it only arrived yesterday. Now, since it is such a major upgrade and I am flying out of NZ this Saturday I have decided to leave it till after UNICON.

But just had a thought today- a 26’’ tube blown up just about fits a Coker- I wonder if a 29" tube could be fitted in place of the 36’’ Coker inner tube? The weight saving would be at least equal to going tubeless, once you factor in sealants and rim strip.

Has anyone tried this? This may be a safer upgrade because if it doesn’t work I can always stick a 36" tube back on.



I haven’t tried this but am interested in the result when you try it. I doubt it will work though. Too bad about the tubeless setup - I was hoping to check it out in Tokyo.


I’ve been thinking about it for a while but haven’t tried it yet. I suggest using a Schrader valve tube and a valve extender because the Presta would be swimming around in the hole, and afaik there isn’t a variety of Presta valve lengths available in that tube size.

you can also get those little black rubber grommets that go in the schrader sized hole when using a presta valve. those would work on the stock rim.

i suppose if you got it all in there the tube would be pretty thin after a good amoumt of psi.

you could drill a hole in the other side of the rim and use two 29er tubes and half the utimate pressure in each… doesnt that sound like fun?

That’s true but then the Presta may not be long enough for the deep Airfoil rim. That’s what I was thinking about when I mentioned the valve length. With an easy-to-find Schrader extender, this is rectified.

I’d think the 29er tube would expand ok to fit the volume of the Coker, since that’s what normal tubes do in a fat trials tire.

Thanks for the replies everyone.

Jagur- I think the tube should be OK- even though it’s stretched thin- the Coker tyre is 2.2kg of four ply toughness :stuck_out_tongue: . I guess the main risk will be from pinch flats, but the sidewall is so ridid I think you’d be OK as long as the pressure is not too low.

An update: it looks like that plan will not work out either- no 29’er inner tubes in stock at my LBS today- I’m not too keen on using a narrower 700c tube.


hey ken, were you the first to use a 29er tube in a coker?

No, I wasn’t. And I have yet to do so. But as far as I know, this is the first thread on the subject. Although I believe Dave Stockton had tossed around this idea for some time.

Tony Melton was the first person I know of to use a 29’er tube in a Coker.

I believe Tony was also the first person to suggest using a tubeless kit on a Coker. However, I believe the first tubeless conversion was done by Dirtsurfer, followed a few months later by me (gizmoduck). Tony has only recently gone tubeless.

is tubeless hard to do?

nick from swat dose it