The basis for mounting this chainring is a conventional Shimano or SRAM 10-speed cassette with 11 to 36 teeth. There are two ways to accomodate this 41-tooth sprocket:
1. remove the 17 sprocket and mount it. Disadvantage: this results in a large gear jump from 15 to 19. You can do that, but it’s slightly uncomfortable. 2. Remove the 15 and 17 and replace them with the 16 and the big one supplied by Trickstuff.
This results in a more harmonious gradation.
Why 41 teeth?
A 41 tooth cog works with a standard ten-speed derailleur - it's only one tooth more than the usual 40. This means the shifting still works well. The odd number of teeth theoretically ensures more even wear on the teeth.