Abstract: A Rear Wheel Suspension Unit for a folding bike comprising a Rear wheel mounting member pivotally connected to a chassis member and a seat tube/bottom bracket member, through the upper and lower linkage thereby forming a pivoting linkage system and a shock absorber is fitted to upper linkage and the lower fixed bracket to form a fully working rear suspension unit. Further, the unit is designed to be sold as an after market rear suspension for a Folding bike and which can be fitted at the time of purchase or at any time after the purchase.