29'er flat problems

Hi all,
I purchased a Nimbus 29’er to commute to work and home. I pickup thorns daily. With my other uni’s I used Green Slime to combat the problem with good success. The problem I have with the 29’er is that it has a presta valve and I am unable to install the Green Slime because you can’t remove the valve stem. Does anyone have any recommendations as to how to help control this problem? There doesn’t appear to be a tube the size I need with a schrader valve. (700 X 52/47)


does specialized make an “armadillo” tire in that size? those are really sweet and prevent flats like crazy, there’s also slime type liners that you put between the tire and the tube.


My KH-29 came with a schrader valve but the extra tube I ordered from UDC came with a Presta. I too would like to find a source for schrader valve 29 inch tubes–I know they exist because they come stock on the KH-29.

Anybody know where to find one?


Is it a different thorn every time? Are you sure? I say this because I have had phases in my cycling career when I’ve had series of punctures and have only been able to put a stop to it by junking the tyre.

What sometimes happens is a bit of thorn breaks off and is embedded in the rubber just so fat that you can’t detect it. Then you ride, and your weight deforms the tyre and the thorn punctures the tube. I had it on my tandem many years ago, and on my MUni about 2 years ago. Changed the tyre and no punctures since.

Failing that:

You can buy pre-slimed tubes with Presta valves. But I suppose if you bought a new tube, you could buy one with a Schraeder valve anyway.

Run the tyre at a higher pressure. Soft tyres fold round thorns (etc.) and give the thorn a moment to bite. A hard tyre will often just break or dispalce the thorn. Definitely, soft tyres are more vulnerable than hard.

Another option is Kevlar tape between the tube and the tyre. I know it’s available. My limited experience of using it was that it isn’t all that good, though.

Schwalbe makes a 29er tube with a schrader valve. You can order them from their web site, Schwalbe Tubes North America.

You’ll want the AV-19 tube.
AV is their Schrader
SV is thier Presta

Minimum order is $15 which works out to 3 tubes.
I’ve been using the Schwalbe tubes on my Coker. They’re good tubes. The AV-19 and SV-19 fit their Big Apple 29er tire so it has plenty of volume for a big 29er tire.

Thanks guys, I don’t know why I was unable to find that. I guess the first place you go blind is in the eyes :wink:

Bontrager slime tubes

Most Trek or Fisher bicycle dealers have 29er slime tubes under the Bontrager name. They also come in longer valve versions if you’ve got deep rims. I don’t really like liners as I’ve seen more flats caused by the liner itself than the thorns they’re supposed to stop. I’ve also had great luck with 700/35-45 tubes instead of often costlier 52c versions. They stretch after all. Also, go ahead and drill out those rims for schrader valves if you want to slime them yourself.
E pluribus uni

Thorns don’t usually stick in the tube until a couple of rotations after they get picked up by the tyre. You could try rigging up a thorn catcher like people used to do (some still do) on bikes - basically its just a bit of wire attached to the frame with a flexible joint (bit of rubber tubing) and bent in such a way that it just drags on the tyre. They flick any picked up thorns out of the tyre before they get a chance to stick in. Only works with relatively smooth tyres though.

Other than that, I’ve had very positive experiences with Continental Gator-skin tyres - I’ve been using them on my bike for a few years and hardly had any punctures in that time. But I think the biggest they make is 700c x 28, so only really suitable for masochists like Mikefule.


I’ve seen a bike fitted with a kind of metal thingy very close to the tire. The idea is to scrape away little stones, thorns etc. before they work themselves into the tire.

I don’t have a picture, but I’ll try with a bit of ascii art


It’s a wheel cut in half.

=( is the scraper thingy,
O is the rim and tire,
— is spokes, and
o is the hub.

Theyre supposed to work well if the tire isn’t too knobby.

Oh, that was what Rob just posted about. That’ll teach me to read the entire thread before posting a reply :o

You mean there are people like me? :astonished: