I’ve got some Rockshox Recon Tk Gold 29r forks with 100mm travel. I think they are a couple of years old so 2014ish. Can they be converted to 120mm, I’ve heard of spacers being used etc?…

Some do, some don’t – I’m not sure of exactly which models can do this. Generally the only way to be sure is to open them up and see if there is a spacer on the air side you can take out to increase the travel. My Gold RLs disappointingly didn’t have the option to go to 120.

I did on some Recon silvers of about the same year, it was easy enough. Service manual here, the info you want it on page 8 I think.

https://www.sram.com/sites/default/files/techdocs/gen0000000004444_rev_b_sektor_recon_xc32.pdf

Cheers chaps