Bicycle Mechanics - Tube Sizing In Two Different 26inches Tire Sizes

Hello All, I am currently experimenting with two different tire sizes on my mountain bike that is used exclusively on asphalt trails. I am pairing a Continental SportContact 26x1.3 and a Specialized Nimbus Armadillo 26x1.5. I currently have the Armadillo in the rear, but I intend to switch the tires around soon. My main reason for doing this, is really to see what difference it makes regarding speed, comfort, traction etc.

My question is this: The tubes for the two tire types come in different sizes. The two different size tubes I bought from Performance Bicycles reads 26x1.50-2.0 for the Armadillo, while the one for the Conti SportContact says 26x1-1.4. I would like to carry just "one" tube as the "spare" on my rides. Which of the two tube sizes can I carry, and why?

In other words, my instinct is to make the 26x1 to 1.4 the spare, since it will work with the smaller tire for sure. The essence of the question then becomes this: How will a tube rated 26x1 to 1.4 do in a 26x1.5 tire? What are the pertinent issues? Dangerous, unsafe, unsound mechanically........?

Thanks for all responses.

Regards,

The smaller tube should work fine for both size tires. I have an old Cannondale Mtn bike that has a 24" rear wheel & a 26" front wheel. I only carry the 24x1.5 tube. It will expand to fit the 26" wheel if need be.

Go with the 26 x 1.0-1.4, it won't be a problem at all with the slightly larger tire-

If the 1-1.4 tube gets a puncture the air will leak out slightly quicker in the 1.5 tire because the rubber in the tube will be in more tension. The difference wont be anything that you would notice.

Got it. Thanks for all your responses.

Have a good day.

I'd definitely use the smaller tube for a spare. A slightly oversize tube will work, but it will be more difficult to cram into a smaller tire without sticking out under the tire bead and pinch flatting or maybe even blowing out.