Originally Posted by
pegthebeast
The chainring is a 52t and has 3 bolts instead of 5, and I need to get the bike rideable for as cheap as possible.
sounds like an old school 1970's Nervar steel cottered crank or similar. A bit heavier, but still servicable. They usually came as a 52/40 double, so 40T inner rings are available.
On the other hand, Surly makes 21T cogs. you will have to add a couple chain links, but it's still fine.
I run 19T on my TT Pro and it's fine.