High V1 speed?

Hello everybody, 

I have noticed that the 777 calculates pretty high V1 speeds especially when I am really heavy, is this normal? For example, below is a picture of me taking off from KSFO RW 28R inbound OMDB (lot of fuel) and fully loaded in passengers and cargo. As you can see I am taking off with 95% thust and I had flaps 15. I would expect for my VR and V2 to be so high but what about V1? Can someone explain? Here are my V-speeds calculated by the FMC.
V1: 171
VR: 171
V2: 173
I am 100% sure I wouldn't be able to stop with that little RW left ahead of me if I aborted takeoff at let's say V1-1 knot.
Thanks in advance.