I've got one of those tire/rim combinations that are very difficult to mount. Tire= Continental Grand Prix 4000, 700 x 25. Today I was headed along at ~23MPH and the rear tire blew-- pop! -- off the rim. Luckily it was the rear. I've gotten flats but not this catastrophic and not at this speed. Luckily it was a pretty safe situation.

Question: what might have caused this? Is there some usual cause for tires jumping off the rim? I wouldn't have thought this would be likely, given how tight fitting and difficult this tire/rim combination is to mount. I use a tire bead lever thing; when they get mounted I try and push the tire to the edge of the rim so the tube has adequate room to expand. One thing I am reluctant to mention is that I previously used soap to mount these rims. But that was several mounts ago and I think I wiped all the soap off the rim/tires. The other curious thing was that this was at least the second ride since mounting these tires (can't really remember), and the last two were 25, and 50 miles, enough to bounce them off the rim already, I would have thought.

Anyone do this often? Got any ideas?


back on the trainer..

Not seated properly.

When you mount a tire, the best way to prevent this is to inflate the tire to about 20 lbs or so, work the tire into the rim to make sure it's seated, and then inflate the rest of the way. Yes, it is possible to go as far as you did before it popped off.

+1. [/thread]

I really hate this /thread thing.

Ok, then tell us what there is to say that is responsive to the OP that Bannerjak didn't already say?

The fact that your comment relates to the form of my post, not the substance of the thread, is one indica that the substance has already been covered.

To elaborate, "+1" means the previous poster got it right and you agree.

"[/thread]" means the previous poster nailed it, is correct,and there's really nothing to add.

I could have typed "Bannerjak, albeit a hopeless Fred, is spot on, and there is little to add"

[/thread] is easier.

(of course the hopeless Fred part was fun)

I know what it all means. You just come across as elitist when you say /thread.
If there is nothing else to add to the thread the thread will end by itself. You don't have to say /thread.
Just my humble opinion, nothing more.

Then tell me how ranting against my post which says essentially " That covers it conclusively, nothing more to say" adds anything?

Either I'm right, and there really is nothing more of substance to say ( and there really does not need to be further response),

or I'm wrong, and there is something more of substance to discuss.

And what is with all the elitist stuff? If anyone actually looked at my posts, they'de realize that while I do go for the quick attempt at humor, I also have spent as much time as about anyone on here attempting to share my experience and what knowledge I've gatered other the last 40 years.

The price for that may be putting up with a few lame attempts at wit.

I'd say just use +1, although I've used /thread before (not here), but can't you see how someone could view it as snobby?

I'm not ranting. Just letting you know what I think. Let me put it another way: when you say /thread how can you be so sure there is nothing more to add? You don't know everything, do you? Like I said, if there is nothing more to add the thread will end anyways.
I'm just trying to voice my opinion. If I'm in minority I'll just shut up

it's clearly intended as definitive.

If it's right, it's right.

If its not, someone can point out why it isn't.

As for being snobby, if the standard is that we need to all be sensitve to everyone's feelings, and make sure there are no unintended slights, then the humor value of this place is gone, and many people including myself won't bother wasting their time.

What's worse?

Posting "/thread"?

Or complaining about a "/thread" post, then complaining about the thread not ending?

Please do...you are trolling.

I will. I apologize, it was not my intention to troll.

i shake my head at this forum.

this happened to me a few weeks back. i inspected my tire and noticed i could see the "belts" on the bead of the tire. bontrager ended up replacing it under warranty. check out the bead of that tire and make sure its ok.

Im new to this site and cycling,so excuse my ignorance in not quite understanding a few things that were said.When he said he really dislikes the /thread deal and that it seemed elitest.Does that /thread deal mean the previous poster is corrct and that the thread is now done and doesnt need any further insight as in responses?

Also wondering what exactly the meaning behind trolling is?

I love the irony of complaining about an [\thread] post and then going on to prove how much better this thread would have been if it had indeed been [\thread]

What it means is that the answer is both factually correct and complete and that people who wanted a serious answer look no further -- i.e. no need to click through pages of drivel that follow. If you only see +1, it indicates agreement but leaves open the possibility that more answers could follow.

In the case at hand, I could have mentioned the possibility of the tire being defective, but the question was whether there is a usual cause (there is, and it is common). If the tire were separating, this would be obvious as the poster was wondering if something as subtle as a little soap residue could cause the problem (it won't).

Since there are obviously a few people who aren't familiar with the dynamics here, I'll explain how things work.

The most important thing to know is that for this place to stay healthy, everyone must both contribute and benefit. People who want advice can learn about gear, mechanics, training, where/how ride, and a number of other useful things. People who have a basic grip on these things hang out for entertainment.

This place can't just be a place to deal with bike problems. First of all, pretty much anything you can ask has been asked and answered many times (even this discussion about perceived elitism pops up regularly). There's only so much you can say about gear ratios, wheelsets, bearings, basic training, etc.

People who basically have their minds wrapped around this stuff need an incentive to stay so you see a lot of useless chatter. But make no mistake -- that is the lifeblood of the forums because without it, this place becomes boring and people who know what's going on leave.

It takes all types to make this place work and we all have a little fun at each others' expense. But if you stick around, you'll occasionally find nuggets. Just be prepared to sift through the other 99.999% which is crap.

So, did the tire take all of the rim's money? The next time my rim goes out of true, I will figure it got jumped by the tire.

+1

Personally I like to inspect the tyre when fully inflated to see if the bead is bulging anywhere.

I do a version of this when I mount tires. I inflate to 30PSI, then deflate totally and squeeze the tire beads together all around while checking to make sure no part of the tube is visible or trapped anywhere. I then inlfate to full pressure, and look all around to make sure the tire is well seated.

It just means that you agree with the previous poster.
Sometimes idiots come in pairs.

It's actually better to squeeze around while you have low pressure. Once you've done that, spin the wheel to make sure it is balanced. If it isn't, something is probably wrong but with the lower pressure you can probably get it right without bothering to deflate. Then complete inflation and spin again to check for balance -- if it isn't, something is wrong and you need to figure out what.

ok. i'm going to re-deflate the rear tire again, check it (time permitting), but definitely make sure i work it around at low pressure before fully inflating. my two cents about the above ethics business is that this later advice did not come out until well after the +1 [\thread], so even if everything was known, not everything was said.

someone mentioned working the tire closer to the rim. how exactly does one do this? it was also said to "squeeze" the tire at low pressure-- wouldn't that push the tire towards the center of the rim/wheel not towards the rim? i will look at it under low pressure and see if i can get it to seat correctly. maybe a slicker style rim tape would help vs. the more fabric type? to help the tire move freely to the outside towards the rim?

but anyway, seems like it's a problem re: mounting. i'm headed down to remount that thing now. if i never repost to this forum, it blew under high speeds on today's ride.

if anyone still checks this thread... the front tire jumped the rim [fell off the rim, if jumped the rim is not standard patois] at mile 57 today. i actually think i know the problem. the inner tube valve stem ring-thing was too tight, i think, on the last few tire changes. this caused the tube to be forced under (very slightly) the tire bead and eventually i guess create a balloon to force the tire off the rim. i kept the valve stem pushed into the tire on the re-mount, and i think that will do the trick.