wide tire slips on narrower wheel

I have an ATB with the usual 2" tires. I got hold of some used aluminum wheels
(Araya) that are narrower and put them on.

All is fine except that the tire and tube rotate on the wheel, probably during
braking. So the stem gets pushed over in its stem hole, and eventually will
tear from the tire causing an instant flat.

Is there any workaround for this? Maybe putting some compound on the tire
where it contacts the rim, to increase holding power? Or do I have to go back
to my old wheels?


Also, I cannot now deflate the tire by pressing on the valve. I assume it has
something to do with leaning over so far. Has anybody got a link to a cutaway
view of the stem/valve, so that I can see how it works and maybe fix it? Thanks.

On Mar 31, 10:52*am, Jerry wrote:
I have an ATB with the usual 2" tires. I got hold of some used aluminum wheels
(Araya) that are narrower and put them on.

All is fine except that the tire and tube rotate on the wheel, probably during
braking. So the stem gets pushed over in its stem hole, and eventually will
tear from the tire causing an instant flat.

Is there any workaround for this? Maybe putting some compound on the tire
where it contacts the rim, to increase holding power? Or do I have to go back
to my old wheels?

Also, I cannot now deflate the tire by pressing on the valve. I assume it has
something to do with leaning over so far. Has anybody got a link to a cutaway
view of the stem/valve, so that I can see how it works and maybe fix it? Thanks.

Which model Araya rim? Are you inflating it enough to seat the bead?
Are you using a pressure gauge?

On Mar 31, 10:52*am, Jerry wrote:
I have an ATB with the usual 2" tires. I got hold of some used aluminum wheels
(Araya) that are narrower and put them on.

All is fine except that the tire and tube rotate on the wheel, probably during
braking. So the stem gets pushed over in its stem hole, and eventually will
tear from the tire causing an instant flat.

Is there any workaround for this? Maybe putting some compound on the tire
where it contacts the rim, to increase holding power? Or do I have to go back
to my old wheels?

Also, I cannot now deflate the tire by pressing on the valve. I assume it has
something to do with leaning over so far. Has anybody got a link to a cutaway
view of the stem/valve, so that I can see how it works and maybe fix it? Thanks.

just to confirm, presta or shraeder valve ? presta you might be able
to lock in place with a nut; but I think you were describing a
schraeder valve- you'll have to press on the valve to get it to
deflate, you might try turning the tire on the rim to get it to line
up too, the valve sticking up can be used to gain some leverage to
gain perpendicularity; overall your problem might be that the bead of
the tire has stretched- not uncommon- trying a newer tire might verify
this

Jerry wrote:

I have an ATB with the usual 2" tires. I got hold of some used aluminum wheels
(Araya) that are narrower and put them on.

All is fine except that the tire and tube rotate on the wheel, probably during
braking. So the stem gets pushed over in its stem hole, and eventually will
tear from the tire causing an instant flat.

That's a problem I have only seen on snow or sand bikes, where riders
inflate them as little as 5psi for maximum flotation. It also happens
to bikes when their inattentive owners ride on almost-flat tires.

Make sure you are using at least a reasonable minimum pressure in your
tires. 30psi is usually OK for a 2" tire, but your bike may handle
and roll better with more pressure than that. If you ride mostly on
the street, I'd recommend about 50psi.

If your tires have a lot of soap, Armor-All, silicone, or other
slippery stuff on them, clean them off and remount. And if that's the
case, apply special attention to cleaning your rims and brake pads,
because they are sure to be contaminated.

Chalo

Chalo

Jerry wrote:

I have an ATB with the usual 2" tires. I got hold of some used aluminum wheels
(Araya) that are narrower and put them on.

All is fine except that the tire and tube rotate on the wheel, probably during
braking. So the stem gets pushed over in its stem hole, and eventually will
tear from the tire causing an instant flat.

That's a problem usually encountered by snow and sand bikers, who use
pressures as low as 5psi for maximum flotation. It's also a problem
for inattentive bike owners who ride on almost-flat tires.

Make sure you are using enough tire pressure. 30psi is usually OK for
a 2" tire, but handling and rolling characteristics may improve if you
use more pressure than that. If you ride mostly on the street, 50psi
should work pretty well for you.

If you have a lot of soap, Armor All, silicone, or other slippery
stuff on your tires, clean it off. And in that case, clean your rims
and brake pads with special attention, because they will surely be
contaminated.

Chalo

On Mon, 31 Mar 2008 12:02:50 -0700 (PDT), Chalo
wrote:

Jerry wrote:

I have an ATB with the usual 2" tires. I got hold of some used aluminum wheels
(Araya) that are narrower and put them on.

All is fine except that the tire and tube rotate on the wheel, probably during
braking. So the stem gets pushed over in its stem hole, and eventually will
tear from the tire causing an instant flat.

That's a problem I have only seen on snow or sand bikes, where riders
inflate them as little as 5psi for maximum flotation. It also happens
to bikes when their inattentive owners ride on almost-flat tires.

Make sure you are using at least a reasonable minimum pressure in your
tires. 30psi is usually OK for a 2" tire, but your bike may handle
and roll better with more pressure than that. If you ride mostly on
the street, I'd recommend about 50psi.

If your tires have a lot of soap, Armor-All, silicone, or other
slippery stuff on them, clean them off and remount. And if that's the
case, apply special attention to cleaning your rims and brake pads,
because they are sure to be contaminated.

Chalo

Chalo

Dear Chalo,

Another possibility is that the tire slipped on the rim because a
too-wide tire tends to pull its bead away from a too-narrow rim. This
leaves much less tire-rim contact than expected, and the tire can slip
because there's not enough contact area to provide the necessary
tire-rim friction.

With a narrow rim and a wide tire, hoop stress tends to pull the tire
bead away from the rim at low inflation because of the excessively
sharp angle where the tire turns and dives into the rim well.

That is, the pull of the casing on a wide tire seated on a narrow rim
is almost sideways and can tug the hidden lip of the bead away away
from the rim at low pressure.

A crude sketch:
http://i31.tinypic.com/fxf4h1.jpg

With properly matched rims and tires, trials motorcycles run 4-6 psi
rear tubeless tire pressure without rim slip, even with no rim locks,
~400 pound loads, and clutch-popping 10 horsepower accelerations.

This video shows how low the pressures go, with a trials tire
repeatedly rolling over a golf ball and scarcely disturbing it:
http://home.comcast.net/~jc-long/cli...tire-test2.wmv

Cheers,

Carl Fogel

landotter wrote:
On Mar 31, 10:52 am, Jerry wrote:
I have an ATB with the usual 2" tires. I got hold of some used aluminum wheels
(Araya) that are narrower and put them on.

All is fine except that the tire and tube rotate on the wheel, probably during
braking. So the stem gets pushed over in its stem hole, and eventually will
tear from the tire causing an instant flat.

Is there any workaround for this? Maybe putting some compound on the tire
where it contacts the rim, to increase holding power? Or do I have to go back
to my old wheels?

Also, I cannot now deflate the tire by pressing on the valve. I assume it has
something to do with leaning over so far. Has anybody got a link to a cutaway
view of the stem/valve, so that I can see how it works and maybe fix it? Thanks.

Which model Araya rim? Are you inflating it enough to seat the bead?
Are you using a pressure gauge?

Thanks for replying. They a 26 x 1.5 HE VP20 rims

I do not use a gauge to inflate, but since you mention that I'll try it. It is
funny that the front wheel, which once deflated, now is stable. So maybe that
one has more pressure.

Btw, can I just unscrew the valve in the stem to be able to deflate the tire?

That's if I can get at it, with spokes in the way now.

On Mon, 31 Mar 2008 17:50:59 -0400, Jerry wrote:

Btw, can I just unscrew the valve in the stem to be able to deflate the tire?

That's if I can get at it, with spokes in the way now.

Dear Jerry,

If it's a thick Schrader car-style valve, you can stick a tiny valve
wrench into the valve and unscrew the core. You may have to turn the
cap with pliers. Metal valve caps usually have a wrench on the top
like this:
http://www.cyclepath.ca/products/item1109.htm

If it's a thinner Presta bicycle valve, you unscrew the tiny knurled
top piece and push it down.

Pictures of Presta & Schrader:
http://www.sheldonbrown.com/gloss_p-q.html#presta

If your valve is so damaged that it can't be deflated, just cut it off
with a hacksaw or nippers or whatever's handiest.

If you have to cut the valve off, you won't be losing anything. You'd
need a new tube anyway because you don't want to ride around with a
tire that you can't inflate or deflate. A new tube is only a couple of
bucks at your local bike shop or WalMart.

Cheers,

Carl Fogel

On Mar 31, 4:50*pm, Jerry wrote:
landotter wrote:
On Mar 31, 10:52 am, Jerry wrote:
I have an ATB with the usual 2" tires. I got hold of some used aluminum wheels
(Araya) that are narrower and put them on.

All is fine except that the tire and tube rotate on the wheel, probably during
braking. So the stem gets pushed over in its stem hole, and eventually will
tear from the tire causing an instant flat.

Is there any workaround for this? Maybe putting some compound on the tire
where it contacts the rim, to increase holding power? Or do I have to go back
to my old wheels?

Also, I cannot now deflate the tire by pressing on the valve. I assume it has
something to do with leaning over so far. Has anybody got a link to a cutaway
view of the stem/valve, so that I can see how it works and maybe fix it? Thanks.

Which model Araya rim? Are you inflating it enough to seat the bead?
Are you using a pressure gauge?

Thanks for replying. They a 26 x 1.5 HE VP20 rims

I do not use a gauge to inflate, but since you mention that I'll try it. It is
funny that the front wheel, which once deflated, now is stable. So maybe that
one has more pressure.

Hmm, that's not a radically skinny or wide rim. Like others have
mentioned, make sure that the rims and tires aren't greasy and inflate
till the tire seats evenly along the rim. Spin it in the frame and
have a look. If it wobbles, then it hasn't seated evenly.

wrote:

just to confirm, presta or shraeder valve ?

it's the regular kind, with a small metal pin that needs to be pressed down to
release air. Sorry, I don't know the name. The same as a car tire.

presta you might be able
to lock in place with a nut; but I think you were describing a
schraeder valve- you'll have to press on the valve to get it to
deflate, you might try turning the tire on the rim to get it to line
up too, the valve sticking up can be used to gain some leverage to
gain perpendicularity;

thanks, that's worth a try before having to cut it off

overall your problem might be that the bead of
the tire has stretched- not uncommon- trying a newer tire might verify
this

yes, good assumption: it is an old tire.

Also, to Carl: nice explanatory sketch. And now I know about tinypic.com, too.
Thanks.