Does your chain look like this:
If so read on for a picture guide to unlooping your chain. No special tools needed, although if you're like me, you might want to have a drink before going back out. This happened to me twice, and the second time I decided to find out WHY this happened. I have had up to four loops or knots in my chain at one time. Some would consider it punishment, but I purposely re-created the loops to take pictures for this post. If I could recreate them purposely, I should be able to destroy them purposely.
First, I think it is important to understand exactly how the loop occurs. The bike is upside down, the wheel just taken of. The keys are the pedal and the rear derailleur. If the chain that is normally on the bottom part of the circuit (when the bike is being ridden) gets around the pedal or derailleur, and falls below the chain that is normally on top then your first loop forms.
Now one loop probably wouldn't be too bad, and might be easy to fix. Simply take the chain back up around the pedal. But loops love company. The second loop forms when the back sprocket (derailleur pulley) loses its chain as well.
Now, to fix two loops or knots, you have to take two steps. It is important to get the loops as far away from each other as possible. Most people say that simply by "pushing them into each other" they will go away. This is not true. Step one is putting the back loop up and over the back sprocket, and step two is getting the chain up over the pedal. You will probably have to re-run the chain around the gears by the pedals.
Now, what if you have three or four loops? You can create more than two, but to do this you would have to have twisted the chain as a hole, so that the loops are facing up instead of down.
My unprofessional opinion is that you can only add loops one at a time at this point. you ad them off of the derailleur pulley (rear sprocket). You simply repeat the process from above. Notice, however, that the new loop faces the opposite direction as the first two.
I have had up to four loops in my chain. It was at this point that I considered throwing the bike away and getting a new one. But calm, cool, liquor... I mean collectiveness got me through the situation.
For the future, this can only happen if your bike goes from up and down to sideways. This will usually happen when putting the bike into a car. To avoid this in the future, put the sprocket side of the bike up.
Good luck with your chain!
