Upon giving the chain a good clean I found some of the links have seized.
I am pretty sure i have the standard set. I use the bike for commuting and for green lanes. Around Surrey it is fairly hilly. but I do not know. what is the standard sprockets and chain?
Mine has 14/44 standard NZ model... but is a bit to high
So I now use 14/48 for road & it's a simple change to a 12 tooth
engine sprocket for offroad with out having to lengthen /shorten the chain..
12/48 is about the same ratio as 14/51....