By Johan Bornman 

Chainsuck really sucks!

The worse a rear sprocket is worn, the more likely a new chain will skip. A slightly worn sprocket will only produce skip under very high loads. On the other end, chainrings last much longer than sprockets. They do wear, but because the chain enters them under force, it won’t skip. However, a badly worn chainring refuses to let go of the chain in what is known as “chain suck”.

Chain suck happens when the chainwheel’s cogs are worn into hooks that do not allow the roller to freely disengage. They hold onto the chain where it should normally exit and rolls it up the rear of the chainwheel and jams it under the incoming chain. Chain suck can even bring your pedalling to an abrupt stop. Experienced mountain bikers quickly develop an ear and technique that saves the drivechain from self-destructing under powerful pedalling forces whilst the chain is, should we say, being sucked?

Very dirty chains, particularly on muddy mountain bikes, suck because the dirt jams the chain around the sprocket. Mountain bikes - with their long cage rear derailleurs - are more prone to chainsuck than road bikes (with shorter derailleur cages). Water cures chainsuck caused by dirt, and that’s why you’ll often find mountain bikers bathing their bikes in streams during foul-weather rides.

And remember: if it ain't broke, fix it!