Instead of measuring saddle angle the old school way using a plumb line, download the Leveler App to make your life a lot easier. It's simple to use, free and seems to be just as accurate as a $40 dedicated angle finder tool.
HOW TO GET THE LEVELER APP (ANDROID):
If you go to the Android Market aka. Google Play Store, search "angle finder" and download the Leveler app created by chkuentz. In order to use the free version of this app, it will require you to download Adobe Air. If this is a deal breaker, you can download Leveler Pro for $0.99 and avoid downloading Adobe Air. It's still a lot less expensive than driving to and buying an angle finder at your local hardware store!
HOW TO USE THE APP:
Ok, so it's not exactly a free app if accuracy is extremely important, which in this case it is. Before using the app, you'll need to calibrate the phone on a level surface- the only way to be sure that you're calibrating it on a level surface is to use a bubble level. If you don't have one, you'll need to buy one.. but most likely, you already have one sitting in your garage or tool box. You'll notice that even on a counter top which appeared to be level, I needed to put two sheets of paper under the left side to level it out. I could have probably used more.
After you've calibrated the phone, you can go ahead and use it to check the position of your saddle! If you have a saddle with a varying slope like the Selle SMP Evolution, try to find the flattest part of the saddle to get the most accurate read out. The key is to be able to produce repeatably accurate measurements. Take note of where you placed the phone and measure the angle at least three times. Most importantly, write down your measurements (with the date and some subjective notes about how the saddle position felt) so that when you decide to experiment with different angles, you remember where you left off.
