velospace blog

Chances are if you run a website you also publish a RSS feed. Feeds are valuable because they allow users to see if your website has been updated since their last visit. velospace has several feeds – customizable feeds for new bikes and another for comments.

Measuring RSS subscription rates has traditionally been difficult (a feed is just a text file after all), and FeedBurner moved into this space early on. But what if you don’t want to consolidate your feed subscriptions through a third party like FeedBurner?

The Official Google Reader Blog has a partial solution – several RSS feed readers including Google, Bloglines, NewsGator, Feed Path, Rojo include the number of subscribers in the HTTP request User-Agent string.

The User-Agent string is information a web browser sends to the web server, which stores this information in a log file. A typical User-Agent string looks like this:

"Mozilla/5.0 (Macintosh; U; Intel Mac OS X; en-US; rv:1.8.0.9)
Gecko/20061206 Firefox/1.5.0.9"

Reading through it you can see that the User-Agent string tells us that the person is running Apple OS X and Firefox 1.5.

A User-Agent string from a feed reader looks like this:

"Feedfetcher-Google; (+http://www.google.com/feedfetcher.html;
16 subscribers; feed-id=15996711146216185864"

Notice the bold part – this is the interesting stuff. 16 people use Google Reader to grab velospace updates. Search for “subscriber” in your access logs to find these User-Agent strings.

Searching through the velospace access logs a quick informal count puts the site’s RSS readership at around 50 or so subscribers. It would be possible to search the logs and automatically parse out the feed subscriber numbers, but this assumes that all of the feed scrapers report this information in their User-Agent string.

- Greg