i have a macargi cruiser motorbike with an extra wide pedal crank to fit around my 49cc flying horse engine/// ok so, i was riding down the street like norm when all of a sudden my crank came loose. The chain came off and i couldnt even brake seeing as i have coast brakes ANYWHO i dont know how to or even start to fix it. it looks like i just have to take it off and tighten these bearings things that are next to the chain sprocket. also it looks like theres metal shaving all inside there. is that terrible? . HELP & Thanks . > .