Tire rotating on rim?

[Kurt Nordback]

I have an odd problem that I'd like to get input on. I've had repeated instances of tubes blowing out at the valve stem on my front wheel after hard braking on steep descents. Each time, the rim tape has been pulled or stretched against the valve stem. It seems like the tire is rotating on the rim, pulling the tube and rim tape with it.

The rim is a Velocity Dyad (wheel built by Peter). The first two times it happened I had on a Panaracer Gravel King, running fairly low pressure (I was on rough gravel). I thought maybe the more supple tire was the problem, so I put on a Continental Top Contact, which is pretty stiff. But it happened again this morning coming down the mountain outside town (behind a slow-moving car, so I was braking a lot). And that was on pavement so I was running higher pressure, 40-50psi.

After the first time I filed down the valve stem hole to avoid a sharp corner, but that didn't fix it.

For many years I had a Sun Rhyno Lite rim on this wheel, and never had a problem. I'm wondering if the Velocity rim maybe has a tiny bit smaller diameter and so allows the tire to rotate due to hard braking force. I'm wondering if anybody out there has had similar experience or ideas on how to resolve this.

Thanks.

-- Kurt

[Peter Bense]

Not trying to start up an old rumor, but I remember reading about some issues with Velocity rim sizing awhile (over 10 years) ago.  I think this was before they moved production from Australia to the US.

https://www.bikeforums.net/15214177-post4.html
"..rumor has it the new rims coming from Velocity's new US factory are better sized and more consistent than the aussie stuff was. no idea if this is fact or just noise..."

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[GTB]

In my limited experience, a properly seated tubed tire never comes in direct contact with the rim tape after it has been mounted.

I have damaged valve stem and area around the stem in a manner similar to what you describe, but the rim tape was not was associated. 

In my case, I was running tubed tires with low inflation and under heavy braking, the tire and tube would rotate on the rim and the valve stem and surrounding area would become damaged.

For quick test, maybe wrap rim with over wide rim strip, electricians tape or similar and if you can remount the tire, the wheel diameter is might be too small.

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- Marvin Davis

  Semper Birotas

[Peter J Leiss]

Rim brakes or disk brakes?

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On Jul 8, 2022, at 4:29 PM, Peter Bense <text...@gmail.com> wrote:



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[Kurt Nordback]

Rim brakes

[Kurt Nordback]

This is an interesting idea. I'll try it and report back.

[clayton]

Here’s some ideas…  

I’ve dealt with this problem myself.

 Scrub down everything, inside of the tires, tire beads, rims and tube.  Use LOTs of dawn dish soap, a scrub sponge, brush and grout brush for the rim.  Rinse far longer than you think is necessary.  Let dry.  You want everything to be squeaky clean.   If your using a rubbery or plastic rim strips for tubeless tires, ditch them immediately, and wrap the rims with cloth rim tape that has adhesive on the rim side.  Important!  There’s a brand…… I can’t think of the name.  It’s a classic, readily available tape.  Use the correct width and wrap once, ensuring it fits perfect at the bottom of the rim right up to, but not up, the sidewalls. 

 Ensure you’re using the correct sized tube, pre-inflate to just round it out, install the tube and mount the tire.  Don’t use baby powder. Over inflate, up to the pressure rating, let sit for a few, then drop your pressure to what you want. 

The tube will form against the rougher cloth rim tape (more traction).   The beads will be clean and sticky against the rim lips, and the tube and tire will stick against each other.  This should solve your problem.  It fixed mine.  Silty dust got impregnated into my beads and allowed slip at very low pressures. (20 psi on a 2.35)  Get the beads real clean, but not roughed up.

If this doesn’t work,  pull off the tires, apply a very thin coat of Rubber Cement to one side of the tire on the bead rim interface. Let dry, reinstall.

If that doesn’t work,  remove the rim from the hub, and… BEAT THAT PIECE OF CRAP INTO PIECES WITH A SLEDGEHAMMER! 

(until you’re exhausted).

Clayton

[Steve Palincsar]

On 7/8/22 10:21 PM, 'clayton' via Bicycle Lifestyle wrote:

 There’s a brand…… I can’t think of the name.  It’s a classic, readily available tape.  Use the correct width and wrap once, ensuring it fits perfect at the bottom of the rim right up to, but not up, the sidewalls.

[Peter J Leiss]

Rim brakes prolonged braking tube blows out this is more common than you may think. Pretty sure that the problem is the rim overheating from braking causing the tube to fail. I have used Dyad rims on our tandem for a long time and can say that the tire is not moving. We have disk brakes but if the tire could move it would do the same thing. Tires we have used are Continental Gator skins 28 and 30 mm and now Rene Herse Bon Jon 35 mm . Never had one move even under extreme braking. However on our first Tandem rim brakes I did have one front let go after a long braking session. The rims were bloody hot. Failing at the valve is likely a coincidence IMHO

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On Jul 8, 2022, at 10:25 PM, Steve Palincsar <pali...@his.com> wrote:



On 7/8/22 10:21 PM, 'clayton' via Bicycle Lifestyle wrote:

 There’s a brand…… I can’t think of the name.  It’s a classic, readily available tape.  Use the correct width and wrap once, ensuring it fits perfect at the bottom of the rim right up to, but not up, the sidewalls.

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[satanas]

FWIW, I've heard of this happening more at very low pressures off-road, and seen suggestions that gluing the tyre bead to the rim on one side can solve the problem on trials bikes. BITD, I had some movement on MTBs occasionally, but never to the point that damage occurred.

There are two separate issues here, movement and damage; it's possible to have problems with the base of the valve with no movement (i.e., 1980s Alex Moultons with Weinmann rims and nuts at the base of the valve), or a little tyre rotation without the base of the valve being cut.

Higher pressures in the tube will press the beads more firmly against the rim, reducing the chance of movement, otherwise one needs to make the fit tighter somehow. Bear in mind though that if things are too tight repairing flats can become extremely tedious. Tubeless might work too, as then tyre rotation on the rim wouldn't mean valve movement.

Later,

Stephen

[Kurt Nordback]

Thanks for all the info and suggestions. I'm trying Clayton's ideas: cleaned everything and replaced the thinner (FSA) tape with Velox. I don't know how to test it without actually braking hard down a steep hill, so I'll go ride this road again tomorrow.

Tubeless clearly would solve the problem completely, and I may try that if I can't solve it another way.

I'm quite certain that an overheated rim is not the cause. When it happens I of course immediately take off the wheel to replace the tube, and the rim has never been particularly hot. And overheating wouldn't explain the rim tape getting bunched up against the valve stem.

-- Kurt

[Kurt Nordback]

A little update on this, in case anybody's interested:

I did, indeed, test with the thicker (Velox) rim tape. The obvious finally hit me, and I put a mark on the tire where the rim seam is. I dropped the pressure to what I'd go with on a rough road (it wasn't scientific since I didn't have a pressure gauge), and rode down. Sure enough, when I checked at the bottom the tire had moved a couple of centimeters with respect to the rim. Luckily the tube didn't blow.

Then I decided to prove to myself that the problem was the rim. I swapped on a road-bike wheel, with a Mavic rim I've had for years, but with the usual tube and tire I've been running on this bike. I repeated the experiment: rode up, made sure the tire mark aligned with the rim, dropped the pressure, and rode down. And almost at the bottom, the tube blew out at the valve stem, and the tire had rotated by at least two centimeters on the rim.

So it's not unique to this rim, or this tire, and I've now gone through several tubes.

The only real solutions I'm seeing at this point are:

1. Glue the tire to the rim, which would be a pain.

2. Go tubeless, which solves some problems and introduces some others.

3. Keep pressure up on steep descents, and go slower or deal with getting shaken like James Bond's martini.

-- Kurt

[dwluca...@aol.com]

Have your tried rosin on the tire and rim.  You can buy small packs of rosin at any bowling alley and of course on Amazon.  The rosin will definitely increase the friction between your tire and rim and may be the solution you are looking for.

Dave

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[bkfree]

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