In one form of variable compression ratio engine, a connecting rod of an internal combustion engine is coupled to the rod receiving crank shaft by an eccentric connecting rod bearing.
Additionally, a lubricant discharge path (23), which discharges a lubricant to the outside of a connecting rod (4) when connected to an internal path (3C) formed on the crank shaft (3), is disposed on a connecting rod bearing (6).
Pivoting of an eccentric portion of the eccentric connecting rod bearing relative to the crank shaft pin by a compression ratio adjuster varies the compression ratio of the engine.
A middle axle (10) is used as the crank shaft, and one end of the connecting rod (8) is rotationally connected with the rod journal of the crank shaft (10), the other end thereof is connected with the member of the bicycle frame (5).
According to the invention, the filling bodies are provided in a holder (10) having an annular, circumferential wall (10a) surrounding said crank portion (12).
In order to increase the crankcase compression of an internal combustion engine, the crank portion (12) of the crankshaft (11) of the engine is provided with filling bodies (14, 15) of a lightweight material.