Need to cut my carbon extensions. Can I use a copper pipe cutter to do this? Seems like the best way (for me) to get a straight cut if it works. Anyone tried it?
Copper is pretty soft and I am not sure if a copper pipe cutter would be the best.
This would be better: http://parktool.com/products/detail.asp?cat=51&item=SG-6
2X what Raptor said. Pipe cutter will probably crush brittle carbon fiber or at least give you a really nasty looking cut. Plumbing pipe cutters work because copper is soft.
You definitely don’t want to use a pipe cutter for carbon. Head to your local hardware store and pick up a hack saw blade with the highest tooth count per inch they have.
use a fine hacksaw and a saw guide if you need one to keep the cut straight. As mentioned, you cannot squeeze carbon like in the manner of a knife style pipe cutter as it will fracture badly.
Dont do it! Pipe cutters work well on aluminium, but not a good idea at all on carbon fiber. Because they compress cut they splinter the fibers and delaminate the layers. Use a 32T new sharp hacksaw blade and I would suggest using a cutting guide as well.
And wear a mask.
Kevin
So are you saying it’s fine to use a copper pipe cutter on alloy extensions? Because I’m trying to find an answer to that one as well.
A hacksaw blade with a very high tooth count is fine.
A “grit” hacksaw blade is better. (This is kinda like a very thin rod covered in sandpaper-like material.)
A chop saw (or miter saw) with a grit blade is still better.
Be sure to wrap the area you are going to cut with a couple of layers of masking tape, and cut right through it. This will keep the splintering to a minimum.
Measure twice, cut once.
Steve
I have used it before, but still prefer the cutting guide and blade.
Kevin
Thanks for all the responses guys! Guess I will head to the hardware store 
Use a hacksaw and a fork steerer tube cutting guide.