Creating a detailed SVG image of a pelican riding a bicycle involves defining the shapes and paths for the pelican, the bicycle, and their interaction. Below is a simplified version of such an SVG. Please note that creating a highly detailed and realistic image would require more complex paths and shapes, which can be quite extensive. This example aims to give a basic representation.

```svg
<svg width="400" height="400" xmlns="http://www.w3.org/2000/svg">
  <!-- Pelican -->
  <path fill="#8B4513" stroke="white" stroke-width="4" d="M150,100 Q200,50 250,100 Q300,150 250,200 Q200,250 150,200 Z"/>
  <circle cx="180" cy="120" r="20" fill="white"/>
  <path fill="white" d="M170,140 Q190,160 210,140"/>
  
  <!-- Eyes -->
  <circle cx="165" cy="130" r="5" fill="yellow"/>
  <circle cx="195" cy="130" r="5" fill="yellow"/>
  
  <!-- Beak -->
  <path fill="white" d="M150,100 Q160,80 170,100 Q180,120 170,140"/>
  
  <!-- Bicycle -->
  <rect x="200" y="200" width="100" height="50" fill="#6B8E23"/>
  <circle cx="250" cy="250" r="30" fill="white"/>
  
  <!-- Handlebars -->
  <path fill="black" d="M260,230 Q265,240 260,250"/>
  
  <!-- Wheels -->
  <circle cx="250" cy="300" r="30" fill="#8B4513"/>
  <circle cx="250" cy="180" r="20" fill="white"/>
  
  <!-- Pedal -->
  <path fill="black" d="M260,300 Q265,310 260,320"/>
  
  <!-- Seat -->
  <rect x="230" y="280" width="40" height="30" fill="#6B8E23"/>
</svg>
```

This SVG code creates a simple illustration of a pelican riding a bicycle. It includes basic shapes for the pelican (body, beak, eyes) and a bicycle (frame, handlebars, wheels, pedal). The colors and shapes are kept simple for clarity. To enhance this illustration, you could add more details, such as feathers on the pelican, a more detailed bicycle with gears, or a background, by expanding the SVG paths and adding additional elements.

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