You need to count the number of gears you have at the front, and the number at the back, and add the two numbers together. If it is an odd number you will have found out what has happened to that missing number 2 cog. When you find it, you can use it to lever out the chain. If the sums don't add up, use a chain whip to "persuade" the little fella to come out.
You need to count the number of gears you have at the front, and the number at the back, and add the two numbers together. If it is an odd number you will have found out what has happened to that missing number 2 cog. When you find it, you can use it to lever out the chain. If the sums don't add up, use a chain whip to "persuade" the little fella to come out.