Patent ID: 8500081

Claim:
A seat tube of a bicycle comprising: a tubular body having a top end; an insertion hole axially defined in the top end of the tubular body and having an inner surface formed in the insertion hole; a tightening recess recessed in the inner surface at the top end of the tubular body and having an opening formed on the top end of the tubular body; and a supporting surface radially formed on the inner surface of the tubular body and being opposite to and spaced from the opening; a stationary block fixed on and supported by the supporting surface of the tightening recess and having a top; an inner end shaped corresponding to the inner surface, facing the insertion hole and having a thickness; an outer end having a thickness larger than that of the inner end; an oblique surface defined in the top of the stationary block; a fastener hole defined in the oblique surface; and a bottom being opposite to the top of the stationary block and abutting with and supported by the supporting surface of the tightening recess; a tightening block embedded in the tightening recess, mounted slidably on the stationary block, shaped corresponding to the tightening recess and having a sliding surface shaped obliquely, abutting and mounted slidably on the oblique surface of the stationary block; a tightening surface shaped corresponding to the inner surface; a through hole defined through the tightening block: a fastener mounted through the through hole and engaging the fastener hole of the stationary block and having a fastener head abutting against the tightening block.