WordPress – eCommerce cat/attribute nav

I am currently looking in to setting up a new WordPress site using Jigoshop as an ecommerce solution. The site will only have 1 product say bikes but will have various types/sizes of bikes.

Now I’m trying to determined the best structure for this. I was thinking of making each ‘bike’ is own product. Having various categories for each type – ‘Street’, ‘Mountain’, ‘Cross’ etc and setting the size of the bikes via a product ‘attribute’. This all sounds ok to me but there maybe a better way to sort products into those groups, feel free to explain if there is a better way.

Now where I’m getting stuck is I want to have a sidebar menu that lists following.

1. Street
   • small
   • Medium
   • Large
   • X-Large
   • etc
2. Mountain
   • small
   • Medium
   • Large
   • X-Large
   • etc
3. Cross
   • small
   • Medium
   • Large
   • X-Large
   • etc

But I can’t think of a way to list all the categories and then by size attribute. Can anyone help me with how id go about breaking the menu down like this?

really appreciate any input.

Ok so I’m still struggling with this, I’ve tried the following code but its not quite.

$pos_tax = 'pa_tyre-position';
$terms = get_terms( $pos_tax, '' );
if ($terms) {
foreach($terms as $term) {
    echo '<p>' . '<a href="' . esc_attr(get_term_link($term, $pos_tax)) . '" title="' . sprintf( __( "View all posts in %s" ), $term->name ) . '" ' . '>' . $term->name.'</a></p> ';
    echo get_the_term_list( $post->ID, 'pa_size', '<li>', ',</li><li>', '</li>' );

}
}

Can anyone help me fix this? Its listing out terms the don’t belong to the top taxonomy