niuoka

so Ive got an older trex that has the isis BB. the other day I found another chainring and crank set up that I wanted to give a try. the crank arms are 175 ( instead of my current 170) and the biggest chainring is a 52 instead of my current 48. The current chain rings are starting to look a little worn.
when I went to install the "new" system the chainring slides all the way on and hits the frame not allowing it to turn.
I really don't know what the issue is. And I cant switch parts form one to another as the "old" chainrings and crank arms attach with 4 pins and the "new" is a 5 pin.
I thought that maybe I just have to switch to a wider cartridge...when money allows..but would that mess up my chain to rear cassette alignment and how would I determine how much wider to go...if that is something I can do.
The guy I got the chainring from is a good guy and I don't have to buy it if it does not work. He is not all that knowledgable either and said maybe im trying to put a version 1 on a version 2 ? When I look that up I come up with octalink systems...which I thought were not the same
BTW this is the second time this year I have tried to put on different chainrings...the first time is when I discovered the difference between 4 bolt and 5 bolt
going to a 52 count would probabally not make that much difference, but on the flats when I am in top gears...I know I could go faster with little more effort. And down hill I can out pedal what Ive got

ideas ?