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what is "chasing" ??(4 posts)

what is "chasing" ??steveq
Mar 26, 2001 4:16 AM
recently picked up a new frame that had some dust and grit in the bottom bracet shell. i got 99% of it cleaned out but apparently some grit still remained cause the bb was a real b$%tch to install. i got concerned about ever being able to get the thing out again so i removed it. my builder suggested i get the bb shell "chased". first, what exactly is "chasing" and is this something i can accomplish in my little basement shop?........ thanks in advance. steve q
Mar 26, 2001 4:53 AM
in bike mechanics' terms is running a tool through the threads to clean out all thatcrap that you just ground into them- avoids damaging both the BB shell and the BB itself... oh well, there's always next time. BTW, if it was "a real b$%tch to install"- and you really cranked on it- it was probably due to more than a little grit in the threads. I bet you cross-threaded it... bummer.
What kind of bike?Spoke Wrench
Mar 26, 2001 5:12 AM
"Chasing" is running the correct tap through a threaded hole to clean up the threads. Loose grit and paint will frequently make a part hard to thread.

How lucky are you usually? Go to the hardware store and buy what will look like a brass bristle toothbrush. Run this brush around the inside of the BB in the same direction as the threads. If you are lucky, this will solve your problem.

If that doesn't fix it AND you have a fairly current, medium priced bike, better bike shops will have the correct tap to reface the threads. If the thread damage isn't too severe, they should be able to fix it.

Beware of older French and Italian bikes. They may have bottom bracket threading that differs from the English standard that is most common in the US.
chasing ?steveq
Mar 26, 2001 6:15 AM
the frame is a 2001 fort aero tt with a 68 shell, english. i chose a "set it and forget it" bb... shimano cartridge, square spindle. thanks for the input. i was able to clean out a bunch of the grit that was crunched down into the threads and i'll use a stiff brass brush to get out the rest. i don't think i cross threaded cause there doesn't seem to be any damage visable. btw, the bb came out a whole lot easier than it was installed.. thanks again. steve quinn