I'm looking to rent a touring bike (500cc—1000cc) in Surat Thani or, if not possible, Nakohn Si T.
I've been unable to trace any rental places online.

Can anyone help?

These two towns are not really tourist places, so it might be difficult to rent a big bike. In Koh Samui though, you would be able to find one quickly.

MOVED to local forum for localised knowledge

These two towns are not really tourist places, so it might be difficult to rent a big bike. In Koh Samui though, you would be able to find one quickly.

I am not sure about bike rental in NST or Surrat city areas ......

But when renting bikes on Samui, you are usually not allowed to take them off the island (s) although it can be arranged with some shops .... a large deposit may be required ....it is not easy though!

No big bike rental in Suratthani, well not that I have ever seen.

I'm selling my mint condition CB500F, if thats any good to you

Indeed Surat Thani isn't a touristy area, but there are a lot of foreigner teachers there. For ma bike to rent there is a company called X rentals www.xmotorbikerentals.com

https://www.facebook.com/XRentals?fref=ts

They do monthly and also daily rentals I think not sure if they have the kind of bike you are looking for

Ek only has scooters, he may someone but not all that likely...