I am confused.....by inner tubes.

[pepecat]

I have, on my bike, a 700 x 25 tyre on the back, and i have just put a 700 x 23 tyre on the front. On taking off the old tyre, i thought i would put a new inner tube in as well.
I used a continental race 28 inner tube, and lo and behold..... it was too big. Not too wide for the rim, but too long - like it should be on a slightly bigger wheel.
The measurements on the box say : 18/25 - 622/630 and 700 x 18/25c, 27 x 3/4 - 1.
Now, my bike wheel has 622 as the measurement on it, so presumably this inner tube should fit?

Luckily i had a specialised inner tube as well - 700 x 20/28, 27 x 3/4 - 1 1/8, which fitted fine (though i could have used the old one as well).

Why does one inner tube fit and one doesn't?! I'm confused by all the measurements!
Also a good thing i've never had a puncture, as i've been carrying the continental tube around in my seat pack for about 18 months now. Finding out it didn't fit 20 miles out from home would not have been good.

If anyone wants to buy 5 contintental inner tubes, check out the for sale section!

 

[Ian H]

I've had tubes that appear a little long. My solution is to inflate the tube enough that it takes shape and fit it using talc or chalk. Deflate again as required when fitting the tyre. I carry spare tubes ready talcum-powdered in sealable plastic bags.

 

[Scilly Suffolk]

Like Ian says, you're mistaken if you think they don't fit.

+1 for talc: I keep a small bag of it and drop new tubes in and give them a shake before fitting. Best to avoid perfumed talc though, as some sources suggest they could adversely affect the tube.

 

[Scilly Suffolk]

PS Quality tubes are available, individually for less than £3.

 

[YahudaMoon]

Maybe less air before you seat it in the tyre would be a idea ?

 

[pepecat]

Lol!!

I did inflate the tube a wee bit (so that it took the correct shape) before putting it on the rim. Still too long. The tyre wouldn't have gone over it properly. It was about an inch too long (big) and would have had to have folded over on itself when i put tyre on. It was hanging off the rim when i held the wheel up!

 

[YahudaMoon]

 

[YahudaMoon]

Its a common fenomon nom ? the inner tube being a bit bigger

 

[Deleted member 1258]

I have, on my bike, a 700 x 25 tyre on the back, and i have just put a 700 x 23 tyre on the front. On taking off the old tyre, i thought i would put a new inner tube in as well.
I used a continental race 28 inner tube, and lo and behold..... it was too big. Not too wide for the rim, but too long - like it should be on a slightly bigger wheel.
The measurements on the box say : 18/25 - 622/630 and 700 x 18/25c, 27 x 3/4 - 1.
Now, my bike wheel has 622 as the measurement on it, so presumably this inner tube should fit?

The clue on this is the sizes on the box, the tube is a compromise to fit many wheel sizes, including the old 27 inch wheel, if my memory is right the 27 inch wheel was a smidge bigger than the modern 700c size. I have used that type of tube on a 700c wheel in the past without problems.