Can a tyre 'pop' off the rim while riding?

outlash

also available in orange
I know it sounds stupid but bear with me...

I bought a pair of Schwalbe Rocket Rons a couple of weeks ago for my CX bike but they seem to be too 'big' for the rim in that when you start to inflate the tyre it doesn't clinch the rim and the inner tube tries to escape. I've since tried them on another set of wheels and with a little persuasion, I can inflate the tyre and it holds. Problem is, at the back of my mind, the tyre will give way when I'm on a descent and I'll end up in a heap somewhere.

So can this happen or am I worrying over something that probably won't ever happen?


TIA

Tony.
 
Location
Loch side.
Your fear is understandable and rational. I suggest you test the tyres under controlled conditions, to beyond their limit. This would set your mind at ease.
Get yourself a pair of ear protectors - plugs or ear phones (whatever the protective ones are called) and safety glasses/goggles. Now inflate the tyre to beyond its stated maximum pressure. Go 20% over it. But warn the family and dogs that you're doing a possibly loud experiment. Obviously you take it little-by-little and inspect the tyre as the pressure increases. I suggest you first mark the tyre using a ball point pen or felt tip pen that will show up on the rubber. Draw a mark right around on either side, using the rim as a guide. Pump and inspect. By looking at the line you've drawn, you'll be able to see if the bead is starting to creep.
Let us know how it goes.
 

shadow master

Well-Known Member
Your fear is understandable and rational. I suggest you test the tyres under controlled conditions, to beyond their limit. This would set your mind at ease.
Get yourself a pair of ear protectors - plugs or ear phones (whatever the protective ones are called) and safety glasses/goggles. Now inflate the tyre to beyond its stated maximum pressure. Go 20% over it. But warn the family and dogs that you're doing a possibly loud experiment. Obviously you take it little-by-little and inspect the tyre as the pressure increases. I suggest you first mark the tyre using a ball point pen or felt tip pen that will show up on the rubber. Draw a mark right around on either side, using the rim as a guide. Pump and inspect. By looking at the line you've drawn, you'll be able to see if the bead is starting to creep.
Let us know how it goes.
Seen this with scwhable tyres a few times,nearly always on 700\35c hybrid type sizes,involving disc rims,they look fine,fully inflated, running level,then an hour later they blow off!don't have the answer,but have seen it
 
Location
Loch side.
Seen this with scwhable tyres a few times,nearly always on 700\35c hybrid type sizes,involving disc rims,they look fine,fully inflated, running level,then an hour later they blow off!don't have the answer,but have seen it
I'm not saying this is the case, but with wider tyres it is very important not to exceed the maxium pressure. The bead's resistance to lifting diminishes (as expressed in tyre pressure) as the tyre size increases.

If the Rocket Ron is a lightweight tyre, it is perhaps to light for its own good. The lifting happens because of a) incorrect diameter of the bead or b) a bead that doesn't have enough tensile strength to resist the expanding force c) Poor rim profile design. I suspect a poor bead.
 

Levo-Lon

Guru
If these Rocket Rons are like the 26' version I had on my commencal when it was new id think there normal.
a small child could pop them onto the rim as they seem lose compared to a wire beaded conti.
no tyre levers to remove either just deflate and push off the rim.
mine never poped off tho at 25psi or 40psi

that said the fact that they offer no grip at all is more of a worry as you will soon find out..

have fun and wear a helmet and sort you will out..:thumbsup:
 
OP
outlash

outlash

also available in orange
Thanks all :smile:.

Your fear is understandable and rational. I suggest you test the tyres under controlled conditions, to beyond their limit. This would set your mind at ease.
Get yourself a pair of ear protectors - plugs or ear phones (whatever the protective ones are called) and safety glasses/goggles. Now inflate the tyre to beyond its stated maximum pressure. Go 20% over it. But warn the family and dogs that you're doing a possibly loud experiment. Obviously you take it little-by-little and inspect the tyre as the pressure increases. I suggest you first mark the tyre using a ball point pen or felt tip pen that will show up on the rubber. Draw a mark right around on either side, using the rim as a guide. Pump and inspect. By looking at the line you've drawn, you'll be able to see if the bead is starting to creep.
Let us know how it goes.
I think that's a sensible way to go, I might well try it at the weekend.

is the rim tape seated correctly?
Yep, it's a definate problem with the tyres, not the wheels.

You do have the rocket ron cyclocross and not the 29er version for mtb's?
They are. 700 x 35's

Seen this with scwhable tyres a few times,nearly always on 700\35c hybrid type sizes,involving disc rims,they look fine,fully inflated, running level,then an hour later they blow off!don't have the answer,but have seen it
Funny you should say that, the Sammy Slicks (also Schwalbe) that came with the crosser are very easy to unmount from the rims, but I've never had this problem with them.

That would worry me, think of the side way forces on a tyre when cornering, maybe better off not doing so.
What worries me more is hooning down a 10% decline off road and it decides to go then. That could be messy!


Tony.
 

shouldbeinbed

Rollin' along
Location
Manchester way
Seen this with scwhable tyres a few times,nearly always on 700\35c hybrid type sizes,involving disc rims,they look fine,fully inflated, running level,then an hour later they blow off!don't have the answer,but have seen it
I've experienced it with a 700 x 42 Marathon on my Ute bike, Shimano rims and discs. The bead was faulty and had 6 inches basically flat. It'd just about hold but before I twigged what it was it blew spectacularly while I was riding and very noisily when I put a new tube in and pumped it up to near top pressure.

I tried it a few times out of curiosity before sending the tyre back. Seemed pot luck how it gripped the rim. Sometimes it'd explode off at half pressure mid inflation, others you could get the tyre pumped and leave it a while before the tell tale creak followed by a deafening bang.
 

andyfraser

Über Member
Location
Bristol
I've experienced it with a 700 x 42 Marathon on my Ute bike, Shimano rims and discs. The bead was faulty and had 6 inches basically flat. It'd just about hold but before I twigged what it was it blew spectacularly while I was riding and very noisily when I put a new tube in and pumped it up to near top pressure.

I tried it a few times out of curiosity before sending the tyre back. Seemed pot luck how it gripped the rim. Sometimes it'd explode off at half pressure mid inflation, others you could get the tyre pumped and leave it a while before the tell tale creak followed by a deafening bang.
I had the exact same thing with a Marathon Plus 700x32c tyre. It was around 3 inches of bead that was flat. I didn't notice and it held for a couple of days then blew off at 20 mph. Luckily it was on the back. CRC just sent me a new tyre. I still have the faulty one in the loft.
 

buggi

Bird Saviour
Location
Solihull
I had it happen when I was riding once. I noticed my tyre looked flat but then realised it was off the rim and then about a second later my inner tube blew. They were folding tyres and I put it down to them getting stretched over time. Still use the same tyres and never had the problem since.
 

Tom B

Über Member
Location
Lancashire
I have had a bead fail on a 26" mtb and blow the tyre of the rim at speed. That was on a schwalbe.

Kinda got my attention at 20mph +in traffic!
 
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