What if there was a forum for product reviews? You could have sub-forums: Bikes > Brands > Product, Cyclecomputers > Brands > , Tires > Brands > etc. You could go to the sub-forum you were looking for, then select the Brand name, under the brand name would be the posts. The post title would be the model. At the bottom of the forum would be Requests. Here you could get requests for new subforums and brands.
Just a thought. Maybe it has been thought of before... but I was just thinking it would be kinda nice.