What are my chances of winning a speeding ticket case?

I just got a speeding ticket for a construction zone. I was going 50 when it was a 25 normally a 45. Reason I was speeding was because I was at a traffic light and my lane was about to merge into the other one. There were alot of cars behind me, and I didn't want to hold everyone else up. When I was about to merge the car next to me sped up so I sped up to merge. When I did merge in front of it, the car tailgated me a bit. I sped up a little more to get bigger space between us. Thats when the police saw me and had his radar gun. Does anyone know what would happen in this situation? I want to contest it, but I don't know if I'll win. I never got a ticket before, and I don't know what to do.