Works for Jelly Bean 4.1, 4.2 etc.
- Download drivers for Nexus 7 and enable USB debugging mode on your Nexus 7.
- Connect as Camera (PTP)
- adb reboot bootloader (or Switch tablet in to Fastboot mode (to do so, press Volume Down and Power for a few seconds until text appears on screen; this is bootloader mode)
- fastboot oem unlock
- Download SuperSU v0.97 (CWM-SuperSU-v0.97.zip) and copy to SD card on Nexus 7
- Download recovery-clockwork-touch-6.0.1.0-grouper.img and copy in android-sdk-windowsplatform-tools directory
- adb reboot bootloader
- Browse to android-sdk-windowsplatform-tools directory and open Command Prompt (Shift + Right Click > Open Command Prompt)
- Type – fastboot flash recovery recovery-clockwork-touch-6.0.1.0-grouper.img and press Enter
- Now, select Recovery from Fastboot menu and enter Recovery mode
- Use Volume buttons to scroll to Flash Zip from SD Card and press Power to select
- Now, select Choose Zip from SD Card and confirm with Power
- Browse to CWM-SuperSU-v0.97.zip on device’s SD card and select to confirm installation
- After installation, return to main Recovery menu and select Reboot System Now (this may take a few minutes)