I fitted an alloy freewheel 2 months ago along with a new belt. I have a rwasonable amount of tension in the belt but it has just started slipping when pulling away again. I think it’s the large crank wheel that is the problem so would like to get an alloy one. I’m sure I saw some for sale last year which came in red or blue but can’t find them on the internet now. Does anyone know where I can get an alloy crank wheel for a strida 5, preferably in the UK?