$10 DIY Chain Tensioner, works good on my predator swapped db30 : r/minibikes
Green Bird: DIY chain tensioners
DIY MTB Single Speed Chain Tensioner. On Oval and Round Chain rings! - YouTube
DIY chain tensioner - for certain bike frames there is no wiggle room for chain length and the chain is inevitably too short… | Bike frame, Bicycle diy, Bike design