How vital is inner tube width?

Niffleman

This is probably a silly question, but I thought I would ask it anyway. My wife has just bought a Dutch style city bike and it has 26 inch wheels. According to the writing on the outside of the tyre they have a 1 and 3/8 inch section. I have a mountain bike with 26 inch wheels which have a 2 inch section. I have a couple of spare inner tubes, but the box says they are for 1.5 inch to 2.1 inch tyres. If I need to change a tube on my wife's bike, will they be OK, or does she need a different tube? Is the difference between 1.5 inches and 1 and 3/8 inches vital?

I would appreciate your thoughts.

ride_whenever

you should really use a 1 3/8 tube, but you'll be able to squeeze a 1.5-2.1 tube in there okay.

andrewjoseph

Using a inner tube that is slightly bigger shouldn't be a problem, using a small tube in in a big tyre can theoretically stretch the inner too thin to be safe.

ride_whenever

yeah, a too small tube will just pop (he says, speaking form experience of a 1" tube in a 2.3" tyre :oops:

Niffleman

Thanks a lot for that information everyone, saves carrying two tubes when we are together on the bikes!

supersonic

Remember the 1 and 3/8ths width is (bizarrely) not the same as 1.375. The fractional measurements can have different diameter tubes, not just width. This can cause problems if the tube is therefore too long. 26" x 1+3/8" tyres have a ISO diamterer of 590mm: 26x1.375 is 599mm while standard MTB 26inch tyres are 559mm. You may struggle to stretch an MTB tube in there! ALways check the ISO measurement in mm.

Using smaller width tubes in larger width tyres (given the same ISO bead seat diamterer)generally causes no probs ie the standard 26 x1.75-2.125 tubes are fine for 2.3-2.4 tyres.