playrider

The tires on my Giant TCR2 have always taken a 700 x 20/28c size tube. I specific 700 x 20/28c because when I once accidentally picked up a 700 x 20/28 (no c) sized tube (which went to my wife's bike), I realized there was a slight size difference there.

Now, I have a problem because I can't seem to track down 700 x 20/28c sized tubes. A guy at a local shop said the 700 x 20/28 (no c) is interchangeable despite the slight size difference.

So, I'm throwing this question out to the forums. Has anyone else run into this problem? Have they tried making the 700 x 20/28 (no c) tube work? Please let me know what I might be able to do here.

Thanks in advance!

canam73

Don't worry about the 'c'. Have you ever inflated a tube outside of the tire? They blow up like a balloon. Slight size differences don't matter as long as you can get the tire mounted over it.

wkg

Figure out the width of your tire by looking at the side of your tire. It's probably a 23, 25, 28, 32, 35, 38 etc.

Whatever number it is it will be in the size range of a tube. Get that tube.

Bontrager makes 18-23, 28-32, 35-44 etc. 18-23 will also work for 25s.

Bob Dopolina 

It's the same size tube they just didn't print the 'c' on the box. There is no dilemma.

prathmann

The "700 x 20/28c" indicates that this tube is designed for a wheel with the standard '700c' diameter rim (622mm actual rim diameter, but overall ~700mm when fitted with ancient 'c' width tires) and with tires of a width in the approximate range from 20mm to 28mm. If some tube manufacturer labeled theirs without the 'c' then it just means they forgot to do so - there is no '700' rim diameter standard, only '700c'. Any observed size difference is likely just due to manufacturing variations between companies - just like one clothing makers 'L' shirt might be larger than anothers.

As mentioned above, tubes expand to fill the available space inside the tire, so almost any size tube can be used as long as you can physically get it inside the tire without it being pinched. I use the same tubes in my 20mm narrow tires as in my 38mm wide ones and I've even used tubes of the 'wrong' diameter when necessary - 700c tubes in 26" and even 12" tires, 26" tubes in 700c tires, etc. Just makes installation a little harder.