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Two flats in the rear within two miles....

1K views 21 replies 12 participants last post by  Krunk_Kracker 
#1 ·
I bought two new tires today, Geax Saguaro 29x2.2 for the front, and a Geax AKA 29x2.2 in the rear running tubes. They are wrapped around two new Mavic TN719 rims.

The rims have about 40 miles on them, and they had some no name Kendas (29x2.1) on them before I put these Geax's on today.

I checked both tubes and they both have punctures on the inner side of the tube, where they rest inside the rim. I've ran my finger along the rim and nothing feels sharp or jagged and I don't see anything at all that seems sharp or jagged.

I'm completely puzzled. I've patched both tubes but I don't want to put them back on until I've done a little more research and got a little input.

Anyone have any thoughts on this??


EDIT:

Just checled both tubes and they are sized 29x2.10...although I can't see how that would cause these punctures.
 
#3 ·
Well, theres not any snake bites.

And I thought about that, but I was running 35psi on the rear with the second flat, 33 on the first one.

I've been running 27 front and 33 rear for months on the generic Kendas I've been running before today.

The kendas were wire bead whereas these Geax's are folding, dunno if that has anything to do with it.
 
#4 ·
Mount the tire with the valve stem at a label so you know it's relation to the tube and the rim. Run it again. If/when it flats again you'll be able to know exactly where to look on the rim (or tire) for an issue. What rimstrip are you running? You could run a 26" tube in there and it's not gonna be an issue so the 2.1 is not the problem. With the information you have provided that's really all about you're gonna get. I agree with you though...generally in a pinch flat you're gonna see two nice holes that are very symmetrical. Odd that it would be a pinch and be one hole each time.
 
#8 ·
If it's definitely the rim side, not snakebite, no sharp irregularity on the rim, and your rim tape has completely covered the spoke holes, you've got a mystery.

As far as running Geax tubeless, I have had good success with the TNT's on converted and ZTR rims. If they are not TNT or UST tires, I'd be cautious running them tubeless.


"I ride my bike to ride my bike"- Zen proverb

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#6 ·
I've never had good luck with tubes, particularly in the rear. I've been running tubeless for years with no problems getting flats. If you use UST certified tires and rims that will assure you have a compatible system. One set of wheels that I have are labeled "tubeless ready" so I run a couple ounces of Stan's sealant to ensure I get an air tight seal on those rims. I also run some Stan's in the UST wheels for a little extra insurance. The bad thing about going tubeless is the tires cost more.

I've had a problem with a Kenda Nevagal UST, seems they are not compatible with sealant. My Kenda had a blow out when the sidewall failed, seems the sealant attacks the rubber on the Nevagal.

Recently I tried running some Continental X-king 29er tires in a tubeless setup. That doesn't work either as the 29" X-kings are not labeled as tubeless compatible and there are pin holes in the sidewall that would not seal with Stan's. Seems this is a common issue with 29" X-kings, I went through 2 new X-kings, all with holes in the sidewall. I'll be swtiching back to a UST or tubeless certified 29" tire.
 
#10 ·
It just dawned on me, there isn't any rim tape on them, that's how they came, still wrapped in the plastic.

On another note, my LBS wear I bought them said they go tubeless on these all the time, even though they aren't the TNT's.
Problem solved :~)

No rim tape will definitely cause flats.

I was just going to suggest closely inspecting the rim tape for creases or not quite covering all of the spoke holes. I recently rode a brand new bike that gave me three flats in three rides with the (tiny) holes on the underside of the tube. Replaced the rim tape, that had a crease in it, and no more flats until the tubes were discarded for a tubeless setup.
 
#12 ·
Thanks for helping me figure this out.

This is my first mountain bike, and the first time I've switched rims so I didn't even think of that. I wonder why the wheels came without the rim tape.

This gives me a good reason to go tubeless though, haha.

I was disappointed I only got out 5 miles, these Geax's felt awesome and very grippy.
 
#14 ·
New wheels usually come without rim tape installed unless they say they have it. Some new wheels will include a bag with rim tape/strips in it for you to install. New bikes should always have rim tape in the wheels because it is assumed that the bike is ready to ride.

No excuse needed to go tubeless ;)
 
#15 ·
I went to my LBS after work today and picked up some cloth rim tape, they recommended it over the typical plastic rim tape.

Put it on, remounted the tires and went and hit a few of the jumps to local kids setup in the retention pond, making sure to land on the back tire and no punctures. I won't have the chance to hit the trails again until Saturday, so that'll be the real test.

Holding off on tubeless for now, bought a new helmet instead.

Sent from my XT912 using Tapatalk 2
 
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