Curiosity Killed the Cat

Frank,

With all of this talk about heating the bottom bracket to get it apart why didn't you explain and show the calculation that demonstrated that the steel cup and the aluminum bottom bracket tube hung on an aluminum frame would have a difference in expansion of a couple of thousandths of an inch max even if you COULD get the aluminum to heat faster than the steel cup?

After all, if you blow hot air down there the steel cup with a much lower conduction rate would be getting warmer than the frame with aluminum having between four and six times the heat conduction of hardened steel and there only being a 44% difference in expansion rates to begin with.

This is something that's right up your alley while we had all these things from using a hair dryer to a welding torch trying to light the frame on fire.

Since an 80 C warming difference in expansion would only be a couple mils and what normally jams these cups in is rust expansion from water leaking down the seat tube and onto the threads that are slightly in the open part of the seat tube and bottom bracket interface, this expansion can easily be twice or more what the expansion could ever achieve even if you could get the bottom bracket significantly warmer than the cup.

Or where you sitting back and enjoying the show? This assault on poor Ted with everything from lighting his frame on fire to pounding it into flakes with a hammer was pretty entertaining as long as you weren't Ted unaware that most of the help here isn't since the exit of Jobst and Sheldon.