Inner tube sizes

j-sworks

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Feb 5, 2012
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#1
So I just had my first flat on a road bike,

To be accurate it was actually a tire puncture (some tiny piece of metal road shrapnel) that went through to the inner tube, and I have changed the tube with my spare but I am left with a few questions.

1. Do I need to worry about the 1mm puncture in the tire?
2. The tube that was installed from the shop is a Specialized 700x20/28c, why can not find this size for sale?
3. Does it matter that I replaced the 700x20/28c with a 700x18?
4. Do I need to hunt around for this exact size 700x20/28c?

Thanks
 

joewein

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Oct 25, 2011
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#2
Re 1) If there is any possibility that debris could gradually work its way through the cut in the tyre, the least you should do is apply sticky tape on the inside of the tyre. I always carry some electrical tape in my tool kit.

A more permanent repair can be done with superglue to close the cut and a mixture of rubber dust (from sanding down an old inner tube) and the puncture kit solvent to fill in the hole.
 
May 22, 2007
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#3
1. Do I need to worry about the 1mm puncture in the tire?
That depends on lots of things. Keep an eye on it. That spot will necessarily be weaker as it's been penetrated once.
3. Does it matter that I replaced the 700x20/28c with a 700x18?
4. Do I need to hunt around for this exact size 700x20/28c?
I'd say this depends on the size of your tire. You should use a tube that agrees with the size of your tire. e.g. if your tire is (the very popular) 700x23C size then your 700x18C tube is rather too small. While it might initially work, it will be under tremendous strain and stretched too thin, so it could potentially fail catastrophically tomorrow... or it might last for five years.
 

j-sworks

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#4
Re 1) If there is any possibility that debris could gradually work its way through the cut in the tyre, the least you should do is apply sticky tape on the inside of the tyre. I always carry some electrical tape in my tool kit.

A more permanent repair can be done with superglue to close the cut and a mixture of rubber dust (from sanding down an old inner tube) and the puncture kit solvent to fill in the hole.
I removed the metal from the tire but I was thinking that I should at least seal the puncture, good call
 

j-sworks

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#5
That depends on lots of things. Keep an eye on it. That spot will necessarily be weaker as it's been penetrated once.

I'd say this depends on the size of your tire. You should use a tube that includes the size of your tire. e.g. if your tire is (the very popular) 700x23C size then your 700x18C tube is rather too small. While it might initially work, it will be under tremendous strain and stretched too thin, so it could potentially fail catastrophically tomorrow... or it might last for five

Yeah it's now in my head as I find myself looking at repair kits and new tubes/tires
 

j-sworks

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#6
I'd say this depends on the size of your tire. You should use a tube that agrees with the size of your tire. e.g. if your tire is (the very popular) 700x23C size then your 700x18C tube is rather too small. While it might initially work, it will be under tremendous strain and stretched too thin, so it could potentially fail catastrophically tomorrow... or it might last for five years.
Yes my tires are 700x23, so when my tube, or others say 700x20/28c does this mean that the tube accommodates sizes in the 20-28c range?

This what it says on the specialized tube that was originally in there.

Thanks
 

theDude

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Oct 7, 2011
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#7
Yes my tires are 700x23, so when my tube, or others say 700x20/28c does this mean that the tube accommodates sizes in the 20-28c range?

This what it says on the specialized tube that was originally in there.

Thanks
Sounds like it should. The tubes I've seen/bought use a hyphen instead of a slash which to me show it is a range. But I believe that is what it is telling you, 20-28 range. (some basic searching shows specialized sell tubes with a 20-28 range)

e.g.: 700x18c-23c (this bontrager one i have sitting in front of me). I use 23 tires, so that works for me.
 

j-sworks

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#8
Sounds like it should. The tubes I've seen/bought use a hyphen instead of a slash which to me show it is a range. But I believe that is what it is telling you, 20-28 range. (some basic searching shows specialized sell tubes with a 20-28 range)

e.g.: 700x18c-23c (this bontrager one i have sitting in front of me). I use 23 tires, so that works for me.
This is what thought as well, and it seems that the manufactures use different things to denote range...The spare that I put on was a bontrager 700x18-23c as well