These bikes rip, don't they?!?! So much fun when bombing down some hills.
I'm rocking a Granite Rockband strap. It is big enough to carry the 29" tube and two 25g CO2 cartridges.
https://www.amazon.com/Granite-Rockband-Carrier-Strap-Black/dp/B078HPJNP5/
They make straps that are ment to hold things in place. They are fabric, so they dont wear out paint as much. I'll try to find you a link for them on amazon or something
Edit: I found a link that could work for you. You could also use Velcro / hook and loop or something but that might not work as well
I use this strap 1) because I'm cheap 2) it works! Holds both my tube, tire levers, and multi-tool just fine
Spare tube strap off amazon. Granite Rockband Mountain Bike Frame Carrier Strap for Tools and Inner Tubes https://www.amazon.com/dp/B078HPJNP5/ref=cm_sw_r_cp_api_glc_fabc_gihaGb0RNC8KE
Thanks man! It’s just a Velcro strap I got on Amazon- any will do. This is the one I have