Originally Posted by Kayce

Most bikes that come with track ends do it for style. They are a less good system, a trowback from the olden days. But since people think the want a "track" bike, manufacturers put track ends on the bikes for them. They are useless unless you need them for your time trial bike, or are racing on a velodrome. Horizontal drop outs are the better system, which is why they were the most common, until an even better one came along(vertical drop outs).