Q:

ssd cloned to hdd won't boot in USB

I'm upgrading my SSD on my Lenovo Yoga Pro 2 notebook.
In order to clone the original SSD, I wanted to first clone it to an external device, then boot the computer using the external device and clone it on to the new, now installed, SSD.
I managed to clone the SSD on an external HDD, but this HDD won't boot, blocking the process.
I am first getting a BIOS message saying no windows boot detected/no USB boot detected/no network boot detected. After this I get to manually choose where to boot from, I choose the USB, and it starts but crashes after a while.
Any idea what could be wrong? Is my strategy valid?

A:

After this I get to manually choose where to boot from, I choose the USB, and it starts but crashes after a while.
Any idea what could be wrong? 

Windows doesn't like being booted/run from USB... you need extra utilities/work to get it booting and running from USB properly.
See these other SU questions: 

Can I install Windows OS (Windows 7) on a removable USB hard drive?
Can Windows 7 boot from an external USB or FireWire drive?
Can I install windows 7 on a USB Harddisk?

Maybe also check out: Installing Windows 8.1 I get "You cannot install Windows on a USB flash drive from Setup"

