totheDude

I think that this is a good suggestion.

totheDude

I am stubborn. This would be my last resort. I am not ready to give up, yet.

FBinNY 

You're misreading me.

It's not that those can't work, it's that it's problematic, and needs extra attention to detail, and focus on eliminating the dead air space in the rim, adjacent to the valve.

If you follow the instructions I laid out, this will be behind you forever.

totheDude

And today, the kicker. Another flat. Same tire. Same side towards the rim, another clean cut:



Tire was inflated to 35 PSI.

Well, it's now clear that those Chinese Kenda tubes are complete POS. Ordered 4 more Bell tubes.

soyabean

Kenda tubes are actually Taiwanese made in Taiwan, I use them all the time fine in my flipped bikes without issues because I know I installed them properly.

totheDude

Maybe. But my son and I have a lot of practice on installing tubes now. I doubt we do anything wrong. Of course we push the stem out and try to keep it perpendicular to the rim. Once the tire is in the rim, there's not much else one does than inflating it. We are not cutting the tube while mounting it, or we would hear it when we inflate it.

79pmooney

I forgot to mention a very basic trick that I always do. I always pre-inflate the tube before I install it. And the correct pressure to that is very, very easy IF you use presta valves. (It is so low I probably do not have anything that would tell me the pressure.) I pre-inflate with my lungs. Yup, uncrew the lock on the valve and blow into the tube as hard as I can. Screw the lock shut. Perfect for issue free tube installs.

With Schraeder? Two pump strokes? No idea. (I certainly cannot inflate by mouth against that spring.

I have found that the pre-inflation greatly simplifies getting the tube un-pinched and the tube settling in without any wrinkles. On some tires and rims I have to let some of that air out to get the last bit of bead over but that is OK. The pre-inflation has already done its thing. And that is yet another reason to go presta.

totheDude

Yes, we do that.

I agree that presta valves may be better, but in this case I don't see how the valve itself affects these flats. Are you implying that tubes with presta valves are somehow better than tubes with Schrader valves?

Iride01 

I can only see if I look. And this time I didn't look close enough to notice that it wasn't at the base of the valve stem.

Do you use levers when you put the tire back on? Don't. And be certain that the tube isn't getting caught between the rim and the tire as you roll the bead over the rim.

I had a rash of flats I couldn't figure out one time quite a while back. Sadly it turned out to be my fault and I'd gotten careless.

totheDude

We try to be careful, but it would be a challenge for my 12 year old to replace a tube without making use of the levers.

Kontact 

Levers are fine.

Velox type cloth tape should be the whole inner width of the rim, not just down in the center channel. That would likely fix your problem. Pull it tight and it will conform to the channel shape.

Right:


Wrong:




Before you do anything else, make sure the rim isn't cracked where the slit keeps happening. A crack that is hard to see will expend under air pressure to form a gap. Probably not the problem, though.

totheDude

I agree. Putting on wider rim tape is going to be our next move.

sweeks

Heh... I've done that using a pointy eye tooth to depress the valve!

totheDude

Ok, here we go. 19mm tape in the rims:


As you can see, it was very hard to keep the tape centered in the rim. In hindsight, I should have bought the 22mm tape. Anyway, no more gaps now.
Installed new Bell tube. Let's see how this week goes.

grumpus

I hope the talc they apply to new tubes doesn't have asbestos traces for you to inhale or swallow. The (presumed) sheep, cow and horse excrement that my wheels throw up on farm roads never did me any harm. If you have a pointy canine tooth you may be able to depress the core of a Schrader valve.

79pmooney

I've got 65 or so year old OEMs in my mouth. (I forget when I got them. My bookkeeping wasn't very good back then.) No way are they dealing with Schraders! Warranty ran out a long time ago and I am trying to keep those 3rd party ones on the store shelves as long as possible.

sweeks

Upper canines usually erupt around 10-12 years of age. Wide range, though.

grumpus

I beg to differ - once both beads are in the rim, with the tube at minimal pressure I check all around that the tube is inside the beads and the valve stem is pressed in. Then add partial pressure, check the bead is seated evenly all around and the valve stem is central in its hole; if not, manipulate the tyre until it is (you might need to reduce pressure in order to do this). Then add full pressure and check again; if necessary reduce pressure and manipulate again. Finally you're done: bounce the wheel on the ground and congratulate yourself on doing a good job.

George Mann

I have had many tear issues thru the years with conventional Schrader valves. But once I went to locking Schrader valve tubes from Continental and Schwabe, no more issues.

grumpus

That's odd - I avoid fitting locknuts on valve stems, because they make it more likely that the tube will be stressed by creep. Without the locknut you can see if there's creep, from the angle of the stem, and the fact it can move means it's less stressed when movement does occur.

George Mann

The lock nut (finger tight) plus the thick valve base prevents any movement.

grumpus

Which is precisely why I don't fit it.

George Mann

But you just said you were trying to prevent creep. This is what the locknut is for.

grumpus

No, I said I want to be aware of creep, so I can deal with it before damage is caused. Locking the valve stem doesn't prevent creep more than a little, it just hides it. If you want a mechanical means of preventing creep you can fit rim locks as used on some motorcycles, but I find it usually happens slowly and is easy, if slightly annoying, to deal with.

George Mann

It seems like you are confusing two issues. Motorcycles are ridden at much higher speeds, with much higher levels of friction occuring.

I have yet to see any issues with creep when using the proper locknut fitted Schrader valve tubes on a bicycle.