Originally Posted by M Funkworthy
just to reiterate what the broken robot said, on my tour there was three or four instances when i was in a wal mart or small town harware store looking at the ample stock of 27 tubes and complete lack of 700s. i feel like for that reason 27s may be preferable. would have saved me and my partner some lousy hitching days. (i know so would have carrying three spare tubes, but how were we to anticipate no bike shops from mobile to austin? or the trouble with west texas thorns?)
700c and 27" tubes are basically interchangable. 27" tubes are 8mm bigger. In fact most if not all 27" tubes are just rebadged 700c tubes.
Interchanging these tubes works great when you are using large touring tires, but it probalby won't work if you are using small racing tires.