Racking the beer isn't always a bad thing. It depends on what your brewing. If you are going to rack it off, be clean.
Quote.
"Take a hydrometer reading. Then wait two days and take another. If it is the same, off you go. If it is lower, then wait a few more days. When you're stable for 2-3 days, you know fermentation is compete that is the only actual fact that tells you it is done. Use that approach with every single beer you ever brew, and you won't be guessing any more."
The tool that takes the guess work out of knowing when a beer is done, is a glucose test kit. A hydrometer only measures density. It hasn't the capability to determine if there are fermentable or non fermentable sugars in the solution being measured. A hydrometer reading can be stable for days, due to the yeast dropping out. A stable hydrometer reading doesn't make it a fact that the beer is done. Fermentation may be incomplete, the yeast may have became dormant. Guessing goes away when you know the percentage of fermentable sugar in the beer. Knowing the percentage of fermentable sugar in the beer can help with knowing if something is going haywire with the yeast. Knowing if there is fermentable sugar in the beer, helps at bottling time.... Using the hydrometer, the reading can be stable for days. So, then you decide it's time to prime and bottle. However, there might be fermentable sugar left in solution. The bottling process rouses up the yeast and it starts working on the left over fermentable sugar and priming solution. Hence, the possibility of bottle bombs, gushers and over carbing. Because the krausen falls, doesn't mean that the beer is done. There is a thing called post krausen.