A shock-absorbing seat stay for a bicycle includes a seat tube coupler having two branches each having a first joint portion, two extended parts each having a second joint portion corresponding to one of the first joint portions, two shock-absorption members made of elastic materials and each held between the corresponsive first and second joint portions, and at least two fastener units. ; R2 is H or a lower alkyl group; R3 is H or an optionally substituted lower alkyl group, etc. A steam bypass facility control unit adds a bias value B1 to a control command value V4 of the steam bypass facility to generate a new control command value V5 when the desired steam volume is determined to have reached the limit value. The buffer space is defined by a recess formed in the substrate, a ventilation hole connecting the recess with the airtight area and being formed in the substrate, and a flexible sheet covering an opening of the recess. Moldable material may then be introduced into the mold cavity and may be allowed to remain in the mold cavity until it is self-sustaining. The invention also relates to articles produced from a nanocomposite and a process for preparing a nanocomposite.