Chain guides for the front sprockets of bicycles are disclosed. Drive element including:a determined spiral-coiled mainspring including at an inner end hooking means having a defined profile ,an arbour produced by this method, comprising said support sector for supporting said first coil, and a complementary hooking means having a complementary profile to said profile for pivoting together with said mainspring. Therefore, the data rate can be optimized to maximize the number of video streams that can be delivered to any one subscriber without causing a perceived reduction in video picture quality. Advantageously, inputs to present inventive embodiments may be received either as analog or digital I and Q inputs, subject to selection between input modes using only a single binary input. The appliance is validated using the first identification and a status of the appliance is determined. The roller mechanism in turn comprises a bracket supporting the roller and serves as the head rail for the shade apparatus.