http://planetcyclery.com/ravemen-pr1200-front-light
This is the one I use, Ravemen 1200. I mostly ride the back country roads here in Tennessee, which mean no street lights, pitch black. It helps that I ride roads I normally ride during the day so I am somewhat familiar with the road conditions and route. I would not hesitate going on new roads at night with this light. I keep it on full (1200) and it will last my train time of 1 1/2 hours. My speeds are around 18-20 and some downhill speeds of 35+. I too was concerned about lights that would be bright enough for 20+ speed and I think this one does the job for me. This will be my second year with this light and so far it has held up good. Although I only use it about 3 times a week for four 4 months last year so far. It may or may not work with your current mount. I hope this helps.