Chain skips gears if back pedling!!
Hirst time post a newbie biker so will try to explain best way i can, Having problems putting chain on my new mountain bike " 27 sp" Chain is either to tight " cant get it into front and rear large gears at the same time " or if i lenghten the chain the cahin becomes too slack and rubs against its self on the rear drailier" also when i back pedal the chain skips from the biggest gear on the back to the smaller ones. any advice much appreciated..