April 3rd, 2016, 11:11 AM
Joined: Jun 2011
From: Northern California
Two reasons..umm, or maybe more.
Chain and sprocket wear is much greater when running a smaller countershaft sprocket.
Parasitic power loss from the chain having to bend more to get around the smaller cs sprocket.
You have more anti-squat with a larger rear sprocket.
It's easier to grasp if you imagine a really large rear sprocket, say a 56t... the chain will be pulling somewhat downwards on the sprocket, and it will press the wheel into the ground under acceleration.
Complete opposite scenario..imagine a 16t front and rear...
On acceleration, the chain is horizontal, and the chain is only spinning the wheel, there is no downward pull as with the previous setup. Less traction.
There's more to it than that I'm sure, and I'm probably under qualified to explain it, as I don't quite get it myself. But that's the gist of it.
A 16/48 is better than 14/42 because it looks cool.
Just kidding, the main reason is so you can swap fronts out without breaking the chain.
So you can ride single track one day, and go on a road trip the next day.
Depending on where your axle is located, you will be able to run a 14/50--15/50--16/50 with the same chain.
I still believe 16/48 would be too tall for a FE450, that's why I put the 50t in ^there^ for you.
Gearingcommander.com is a great site for determining what sprocket setups do what.
You may have to input your bike as an FE650e though (transmissions are the same as FE450e).