Single-chain simulations were conducted for the two backbone flexibilities and the two extremes of solvent quality ("good" and poor). To examine the effect of molecular weight on folding kinetics, four different chain lengths were studied: 10, 20, 30, and 40 monomers, corresponding to M n ≈ 10, 20, 30, and 40 kDa, respectively (40 monomer chains were only simulated with the regular-flexibility backbone in the poor solvent). Simulations of a 20mer with a regular-flexibility backbone in the poor solvent were also conducted with a 10× lower friction coefficient, to determine the effect of solvent viscosity on the rate of single-chain folding. A number of independent simulations were conducted for each system type, with each initially run with non-bonded interactions modelled using purely repulsive Weeks-Chandler-Andersen (WCA) potentials to give an extended chain conformation characteristic of a good solvent, before switching to the CG LJ potentials to determine the time scale of single-chain folding.