i doubt his bike came with a chain/chainring combo that isn't compatible with itself. It's either all 3/32 (in which case this setup will work fine) or it's all 1/8 stock in which case putting a 3/32 cog on will also work. Assuming a bike is currently rideable (ie you don't have a 3/32 chain on a 1/8 chainring before you even thouch it) you can replace either chainring or cog with 3/32 and it will work 100% of the time