why would my Martin compound bow lose speed ? I just recently had the string and cable replaced on my bow and when I shot it through a chrono I noticed it was 20 fps slower than before. (272 fps - 250 fps) This doesn't make any sense. I know the string stretched a little but not enough to make that much difference. I have changed nothing else, arrows, tips, fletchings etc.
Did you switch string brands? Granted it seems like a big lose, but string weight can affect speed. I wouldn't think that much, but maybe. Also, do you know exactly what poundage it was shooting at before and what it is now? If the strings are a bit longer, you'd loose poundage. I believe you can twist the strings to gain some speed back, but I'd have to differ to someone that has more experience as to the best way to do this. Welcome to the site by the way!
I gotta speed question, well trying to calculate my arrow speed, (archeryhut calculator) it asks for you to determine weight of your arrow compared to the 350gr. Arrow used to come up with the IBO speed. Are they wanting the total arrow weight, or just the weight of the arrow minus the head? My guess it total arrow weight, but I'm not sure. If I use the formula givin at that website, the arrow weight differance alone makes me lose over 53 fps, the an additional 20 fps for the 2" less draw. That would make me be at about 243 fbs out of my PSE bow madness. Does that sound about right? IBO for that bow is 316 fps and my arrow weight I'd 511gr. Thanks, brian
