The front sprocket change worked well on the CT70 clone so I ordered two more for the Z50 clone and the hack. First gear is much more usable with the two extra teeth. Don't know why these bikes are geared so low from the factory. The worst is the Dong Fang hardtail which needs at least a change on the rear from 45 to 35 teeth. Front sprocket on it can't be changed because of the 520 chain.