Note: Android L is a Developer preview, it is not stable as the KitKat version and it is using ART runtime only, so not all apps are compatible.
Update: The v2.01 release fixes some incompatibility issues with the Android "L" Preview. There is no binary update over v2.00.
v2.01 released - RELEASE NOTES
Download the latest TWRP here:
rename the "openrecovery-twrp-184.108.40.206-hammerhead.img" to "recovery.img"
TRY IT AT YOUR OWN RISK.
Boot into bootloader
For TWRP format cache first
fastboot format cache fastboot flash recovery recovery.img
Flash the SuperSU-v2.01.zip
You now have root access.
Sent from my Nexus 5 using XDA Premium 4 mobile app