I ride a 29er single speed mtn bike and I'm looking to upgrade the crank and BB. It was recommended to get the BMX Redline Flight crank and BB (I'm a big aggressive rider). I'm doing some price shopping and I'm not sure how to determine what Rebline Flight BB to get. My bike has a 68x118 but when shopping for the Redline BB it says the size is American 19mm spindle? Will that work? What do I need to know to get the correct size? Thanks!