Tube size???

Gorteen

I've got a Gravel bike with 650b x 47 mm tyres. I'm lost as to the correct size tube to carry as a spare?

Trying to work out the correct tube size from the number of possible options is a bit of a mystery to me!

Can anyone advise?

nilhg

https://www.boards.ie/discussion/2058346461/tube-size

650b is the same as 27.5in MTB so something like this will work

https://www.bike-discount.de/en/schwalbe-sv-21-tube-for-27.5

Gorteen

https://www.boards.ie/discussion/comment/122011090#Comment_122011090

Thanks. I saw that but does that tube fit lots of different sizes? There seem to be lots of different sizes in small writing at the bottom of the box.

nilhg

https://www.boards.ie/discussion/comment/122011385#Comment_122011385

Yes, tubes expand to fit the available space.

Wishbone Ash

https://www.boards.ie/discussion/comment/122011385#Comment_122011385

Basically you can put a narrow tube in a wide tyre as the tube will expand to fit the available space. However, it's not ideal as the tube will be much thinner if expanded a lot and more prone to puncturing.