Non BMW battery

Hi guys. As most of you know, BMW charges an arm and a leg for thir batteries, thats why I bought a cheaper model for my bike. The only problem is that I tried to fit it but the negative terminal connection on the bike has the bolt fixed to the attachmentand this fixed bolt is to thick to fit through the terminal conne tion on the new battery.

I considered sawing the bolt off and then drilling it out but decided its probably better to ask on the forum first before i start cutting pieces of my bike  ;D

Does anyone have an alternative solution to the problem?