Just a regular innertube. Have had no flats yet though.
I have always been a fan of Continental tires and tubes. For my own ride I go for the best. Either Continental or Michelien has always worked for me.
I got two of these tubes, the first one split at a seam after one day. The second has been ok for a whole two days. I needed 26x2.5 tubes for the Maxxis Hookworm tire which is a really good street tire (using it on a unicycle). Probably should have gotten the Michelin downhill tire. I have patched the one that failed but it is rather worrisome that the seam split.
This tube has worked out great paired with the Geax Street Runner Tire which see at least 175 miles of commuting a week.
