Cannondaleriders

Sounds like you'll have to drill out the broken off screw and remove the axle-nut and re-tap threads into it. THen don't torque the thing down so much. Check your axle bearings too, with the nut loose, they might be shot.

To get the full effect of the pipe, yes you will have to re-map.

I had the same problem when I used to own a Moto. I ordered some of those allenhead screws from the Quadshop. Never used them so if you want them let me know.

ou can probably get the piece of screw out without drilling and tapping. Loosen the other two screws and unscrew the axle nut. ONce theres no pressure on the piece, you can probably back it out with a pic or something. You can usually push it around by one of the burrs from where it broke. If that doesn't work, take the axle nut off, and use a small drill bit. That'll usually grab the screw and turn it on through the threads and it'll fall out the other side. It's pretty small to be using an ez out. If those 2 fail, time to drill and tap like jcv said.