Postage costs added to your basket are estimated, based on the weight and destination of your parcel. Due to the complicated nature and the combination of parts selected in your basket, it is very difficult to automate the appropriate box, sizes and volumetric weight of the order. For example there are some parts that are not heavy in weight, i.e. front mudguard, footboard, handlebar etc, but are too large to be sent by Royal Mail. The basket will only calculate the postage on weight and not volumetric weight and the postage estimated would be less and will need to be changed when processing your order.