Using a slightly smaller innertube OK?

Question

My used bike came with a 26" tube in my 700c wheel and tire. I didn't know and rolled my tire yesterday.

Now, I need a tube. I have a bunch of 700x18-25 tubes, but my tires are 700x38. Is it a bad idea to use the tire?

Answer 1

It's fine though it will result in easier punctures and possibly more frequent need for inflation.  When I raced I used smaller tubes in order to reduce weight and never had problems.