I have french threaded stronglight cranks that i have been able to get off. i wanted to switch them out so i could get some different gear ratios. something between a 40/16 and a 52/16, the original chainrings that came on the crank. and finding a chainring for these cranks is difficult due to the weird BCD and because it has 3 arms. and recently, i broke the smaller chainring because a stackbolt fell out and it bent. so as i am unable to remove the crank or get new chainrings, i was wondering if there are any advantages/disadvantages to having an 18T or 20T cog in the back and a 52 chainring in front. thanks.