We stock many tube sizes to fit every need. Please note that even though a tube size will say 20 x 1, it will fit a 20 x 1-1/8" tire when inflated. 20 x 1-1/8" tubes will fit a 20 x 1-3/8" tire as well. By using the smaller tube sizes, it keeps the weight of the tube down.
When choosing your tube size, please make sure you are getting the proper valve type. PV (or Presta Valve) tube is the skinny type that is designed for thinner rims. SV (Shraeder Valve) tubes are the bigger type valve (same as on your car tires). We now stock PV tube with 60mm valve lengths needed for carbon rims. 40mm valve lengths are standard for aluminum rims.