clincher roll-off revisited

[Spacey Spade]

I was taking a tight right turn and my rear clincher rolled right off the
rim. I am using Cane Creek Aerohead wheels, and have noticed that mounting
tires on the velocity rims is a lot easier than with any other rim I've
ever used. Has anyone else had similar experiences with rims on which it
is too easy to mount tires on?

Note: during the turn I was holding the bike more upright than usual as I
was trying to pedal. Tire is a Specialized Comp Turbo 700x26c. Tire
pressure was around 110psi.

[Kenny Lee]

Spacey Spade wrote:
> I was taking a tight right turn and my rear clincher rolled right off the
> rim. I am using Cane Creek Aerohead wheels, and have noticed that mounting
> tires on the velocity rims is a lot easier than with any other rim I've
> ever used. Has anyone else had similar experiences with rims on which it
> is too easy to mount tires on?
>
> Note: during the turn I was holding the bike more upright than usual as I
> was trying to pedal. Tire is a Specialized Comp Turbo 700x26c. Tire
> pressure was around 110psi.
I'm guessing that you lost tire pressure as you were about to enter the
turn. I've never heard of clinchers rolling off a rim when fully inflated.

Kenny Lee

[Gearóid Ó Laoi, Garry Lee]

I've had one or two blow off due to heat, coming down really steep hills in
the summer.

[Tom Paterson]

>From: "Gearóid Ó Laoi, Garry Lee"

>I've had one or two blow off due to heat, coming down really steep hills in
>the summer.

What pressure were you running on these?
--Tom Paterson

[Jim Edgar]

Spacey Spade at wrote on 7/23/03 4:00 PM:
> I was taking a tight right turn and my rear clincher rolled right off the
> rim. I am using Cane Creek Aerohead wheels, and have noticed that mounting
> tires on the velocity rims is a lot easier than with any other rim I've
> ever used. Has anyone else had similar experiences with rims on which it
> is too easy to mount tires on?
>
> Note: during the turn I was holding the bike more upright than usual as I
> was trying to pedal. Tire is a Specialized Comp Turbo 700x26c. Tire
> pressure was around 110psi.

I've found Specialized tires generally to have very loose-fitting beads, but
have never managed to actually roll one that was properly inflated.

You'd need pretty high speeds and a pretty decent sideways force from the
roadway - tough to do that unless you were fishtailing. Are you sure you
didn't nick it or pinch it on something first?

-- Jim

[Mark Hickey]

Spacey Spade > wrote:

>I was taking a tight right turn and my rear clincher rolled right off the
>rim. I am using Cane Creek Aerohead wheels, and have noticed that mounting
>tires on the velocity rims is a lot easier than with any other rim I've
>ever used. Has anyone else had similar experiences with rims on which it
>is too easy to mount tires on?
>
>Note: during the turn I was holding the bike more upright than usual as I
>was trying to pedal. Tire is a Specialized Comp Turbo 700x26c. Tire
>pressure was around 110psi.

As Kenny Lee mentioned, I would suspect you may have already lost air
pressure in that tire before it came off the rim. If the tire did
indeed have 110psi, the resultant explosion when the tube exited the
tire would have been VERY loud (and left a huge, ragged hole in the
tube). If both of these things didn't happen, you have your answer.

That said, I DID have a Specialized Armadillo blow off at rated
pressure once when warming up on my tandem for the state TT
championship. The bad news is the tube was a slime tube, and it threw
slime everywhere. The good news is that it was the rear tire, and I
was in the captain's position so the stoker stopped all the slime
before it got to me!

Mark Hickey
Habanero Cycles
http://www.habcycles.com
Home of the $695 ti frame

[Spacey Spade]

Jim Edgar wrote:
>Spacey Spade at wrote on 7/23/03 4:00 PM:
>> I was taking a tight right turn and my rear clincher rolled right off the
>> rim. I am using Cane Creek Aerohead wheels, and have noticed that mounting
>> tires on the velocity rims is a lot easier than with any other rim I've
>> ever used. Has anyone else had similar experiences with rims on which it
>> is too easy to mount tires on?
>>
>> Note: during the turn I was holding the bike more upright than usual as I
>> was trying to pedal. Tire is a Specialized Comp Turbo 700x26c. Tire
>> pressure was around 110psi.
>
>I've found Specialized tires generally to have very loose-fitting beads, but
>have never managed to actually roll one that was properly inflated.
>
>You'd need pretty high speeds and a pretty decent sideways force from the
>roadway - tough to do that unless you were fishtailing. Are you sure you
>didn't nick it or pinch it on something first?
>
>-- Jim

The tube didn't have any other hole besides the monster rip from the
explosion. I was leaning in like on a motorcycle so I could pedal, and I
did with some force... plus I had cornered all the way from the inside to
the outside, and on the outside where the rolloff occured the lean angle
compared to the street was even greater because the street slopes quite a
bit from either side to the middle. I didn't do any skiing until after the
blowout. This was my first time to take this graveyard course. I'm
thinking of holding a Crit there... if this happens again I'll have an open
grave for the fall so we can be more efficient. Spacey

[Jay Beattie]

"Tom Paterson" > wrote in message
...
> >From: "Gearóid Ó Laoi, Garry Lee"
>
> >I've had one or two blow off due to heat, coming down really steep
hills in
> >the summer.
>
> What pressure were you running on these?

And are you sure that they were properly seated? It certainly is
possible to blow a tire off the rim, but, IMO, not at the rated
pressure. -- Jay Beattie.

[F1]

So you're saying you weren't riding upright in relation to your bike? If
you stay upright in a turn, all the centrifugal forces will be directed
vertically (in relation to the frame) onto the wheel, but if you are skewing
yourself sideways in the bike, you have introduced a side-force onto the
tire.

"Spacey Spade" > wrote in message
...

> The tube didn't have any other hole besides the monster rip from the
> explosion. I was leaning in like on a motorcycle so I could pedal, and I
> did with some force... plus I had cornered all the way from the inside to
> the outside, and on the outside where the rolloff occured the lean angle
> compared to the street was even greater because the street slopes quite a
> bit from either side to the middle. I didn't do any skiing until after
the
> blowout. This was my first time to take this graveyard course. I'm
> thinking of holding a Crit there... if this happens again I'll have an
open
> grave for the fall so we can be more efficient. Spacey

[James Annan]

Spacey Spade wrote:
> Jim Edgar wrote:
>
>>
>>I've found Specialized tires generally to have very loose-fitting beads, but
>>have never managed to actually roll one that was properly inflated.
>>
>>You'd need pretty high speeds and a pretty decent sideways force from the
>>roadway - tough to do that unless you were fishtailing. Are you sure you
>>didn't nick it or pinch it on something first?
>>
>>-- Jim
>
>
> The tube didn't have any other hole besides the monster rip from the
> explosion. I was leaning in like on a motorcycle so I could pedal, and I
> did with some force... plus I had cornered all the way from the inside to
> the outside, and on the outside where the rolloff occured the lean angle
> compared to the street was even greater because the street slopes quite a
> bit from either side to the middle. I didn't do any skiing until after the
> blowout. This was my first time to take this graveyard course. I'm
> thinking of holding a Crit there... if this happens again I'll have an open
> grave for the fall so we can be more efficient. Spacey

I once rode (briefly) a tyre/rim combination that was so poor that the
tyre kept on pulling away from the rim. I noticed the lump in the wheel
and managed to stop and deflate the tube before it popped, but a section
of the tube was quite clearly exposed and would presumably have popped
had it been thinner/higher pressure. This happened a couple of times, I
ended up riding home slowly at about 40psi and never used that
combination again (mainly the rims to blame that time, I believe). I
don't think I needed to corner hard to generate the problem but it seems
likely that it would make the tyre more likely to disengage.

James

[James Annan]

Jay Beattie wrote:
>
>
> So, why would it blow off if it is not over-inflated, or if there is not
> a gross mismatch between rim and tire?

How do you judge 'gross mismatch' other than with hindsight?

James

[Jay Beattie]

"James Annan" > wrote in message
...
> Jay Beattie wrote:
> >
> >
> > So, why would it blow off if it is not over-inflated, or if there is
not
> > a gross mismatch between rim and tire?
>
> How do you judge 'gross mismatch' other than with hindsight?

Rattles around like a hula hoop on a skinny kid. If it is within the
range of ordinary tightness (meaning that some effort has to be exerted
with your thumbs to get the tire on the rim), then there must be
something more subtle causing the blow off. I am curious to find out
what that is. -- Jay Beattie.

[Tom Paterson]

>From: Spacey Spade

> I'm going to air up my tire to max, as I
>think this makes the tire stiffer to side loads.

If you heat it up with a lot of braking, and it's already at "max", it will
then have "more than max", possible to blow a clincher off the rim. See FAQ,
I've never had the problem (since I use @110lbs as a max) but there are reports
otherwise.
--Tom Paterson