There is a nasty ride halting condition that occurs once in a while — it’s a condition where the chain does not want to “let go” of the chainring — instead, wanting to “Stick” or “Suck” to the chainring and wrap around again. This is usually initiated during a shift — and most often when shifting under power. It’s manifest when the bottom run of the chain does not release from the chainring and gets carried up and around the ring until something binds — usually as it wedges between the chainrings and the frame chainstay.
Now you know “What” it is, here are some typical causes and fixes.
Chain Suck Causes:
Chain suck is usually “Caused” by a combination of factors — not a single item. Contributers are most often (listed in order of importance):
Avoiding the Problem Altogether:
There is no bullet proof way to completely avoid chain suck. Even single front ring systems can have it if they mushroom a tooth by using it as a bash ring. However, to avoid it as much as possible:
Solutions: (If it occurs.)
For whatever reason, it seems like once it occurs, it starts to happen again and again. One time may be an anomaly, but it it occurs more, it usually means something needs to be fixed. So, if you experience chain suck:
Want to know more?
Chain Suck is a complex and involved subject of study. The complexity comes in the many ways that what we call “Chain Suck” manifests itself on the bike, but are caused by several of the above, interacting factors. If you’re interested in reading more, check out this much longer explanation at: “http://www.fagan.co.za/Bikes/Csuck/”.