700 x 23 tyres popping out

[Eammno]

I've spent my cycling life on 27" and 26" wheels, and Schraeder valves.

My step-son now has what looks to be a decent road bike (Giant OCR) with 700 (mm I guess) wheels, with Presta valves.
However he's been riding it with rather soft tyres, and then managed to loose all the remaining air trying to pump them up. So I helped out and managed to get around 100psi in the tyre. However the following day he's reported the tyre bead is coming out of the rim, which I can't believe, I assume the tyre has split where he's been running around under pressure, but having taken a look, that's just what has happened, the bead has popped out of the rim.
After letting air out of the tyre and pumping up to pressure, it did the same.
It looks like I've now fixed the problem by letting all the air out, breaking the bead, all round, both sides and pumping up again.

So my question is will the bead pop out of the rim when run too soft or are there subtle size differences with 700 rims, and any suggestions for what I should do to prevent it?

[Brucey]

if the tyre has been run soft then the wire in the bead may have uncoiled slightly. After this has happened the tyre can be no good for anything.

What make are the tyres?

cheers

[531colin]

Rims and tyres are made to manufacturing tolerances....you can get combinations that are tight and difficult to put on, and combinations that are slack, where you need to make sure that the tyre is accurately centred on the rim....you may have the latter.

[Valbrona]

Get rid of that tyre. Once they have popped out once it can easily happen again. Could be dangerous.

Not every type of 700c rim will take every width of 700c tyre. However, if the wheels came with the bike and we are talking Giant OCR you would expect those to be able to take 23mm.

25mm is becoming a more preferred width for general road riding. They are said to offer a little more comfort, more cornering grip and even be more aerodynamic as well.

[Eammno]

Thanks for the advice! Feels like I've got a whole lot to re-learn...
Regarding sizes is there a 700 and a 700c? Also have I seen a 23c, as in 700 x 23C or was that someones typo, or my imagination?

[Keezx]

C=clincher.

[beardy]

http://sheldonbrown.com/tyre-sizing.html

Scroll down to French Sizes for the meaning of C when you see 700C.

[Eammno]

http://sheldonbrown.com/tyre-sizing.html

Scroll down to French Sizes for the meaning of C when you see 700C.

Oh good grief... so there's a 700c and a 700C?
I though I was getting the hang of this!
Thanks for the link, but it puts me off ever buying a new bike!

[Vorpal]

Does the rim have a label? Maybe you can post what the rim says on it? It should say something like 622 X 23 or 23-622?

Otherwise check http://sheldonbrown.com/rim-sizing.html

I suspect that the bead has been damaged by riding on a tyre with insufficent air in it, and the best thing to do is replace the tyre(s).

Also, if the tyre is meant for *minimum* 100 psi, it's better to run it a bit harder. The rated inflation pressure should be printed / moulded into the side of the tyre. A stiff tyre rated for 100 - 120 may not seat properly until at or near 100 psi. If there is a little leak, that could easily explain the problem the following day.

Wider tyres are less susceptible to these problems, so if you replace the tyre(s), fit the maximum width for the bike (probably 25 mm). Keep in mind that even if 28 mm wide tyres will fit on the rim, the bike may not have clearance for them.

[Vorpal]

http://sheldonbrown.com/tyre-sizing.html

Scroll down to French Sizes for the meaning of C when you see 700C.

Oh good grief... so there's a 700c and a 700C?
I though I was getting the hang of this!
Thanks for the link, but it puts me off ever buying a new bike!

Don't worry too much about it. the naming conventions don't really have much meaning. Officially, the tyre sizes are 700A, 700B, 700C, etc., but tyre labelling often uses 700c. I'm not sure the reason, but they are the same size.

Tyres are also labelled according to the metric size, so 622 X 25 or something like that.

[531colin]

Officially, 700a and b are obsolete....they were different to 700c
(the 700 referred to the overall diameter....so a fat tyre had a smaller rim)

So...its 700c....where the overall diameter isn't 700mm, it varies with tyre size.....and the tyre bead diameter is 622mm, as specified by ETRO
so the logical size is the one nobody uses, 622 x 23

Confused?.....bet your ass!

[Vorpal]

Officially, 700a and b are obsolete....they were different to 700c
(the 700 referred to the overall diameter....so a fat tyre had a smaller rim)

So...its 700c....where the overall diameter isn't 700mm, it varies with tyre size.....and the tyre bead diameter is 622mm, as specified by ETRO
so the logical size is the one nobody uses, 622 x 23

Confused?.....bet your ass!

Sorry! I didn't mean that 700A and 700C were the same thing, but I didn't phrase it very clearly, did I? I just meant that 700C and 700c are the same thing!