I asked the same question. She doesn't know - I think the bike was pulled out of a skip (before the motor was added). I think it is meant to clear mud off the chain before it goes through the derailleur.
It’s a chain tensioner, handy when you have an illegal motors attach to the bike.
@edscoble started
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I asked the same question. She doesn't know - I think the bike was pulled out of a skip (before the motor was added). I think it is meant to clear mud off the chain before it goes through the derailleur.