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What are facing, tapping and chasing a bb or headtube?(7 posts)

What are facing, tapping and chasing a bb or headtube?Sempi
Mar 2, 2002 1:05 PM
Would like to know what these terms mean.
re: What are facing, tapping and chasing a bb or headtube?Spoke Wrench
Mar 2, 2002 3:00 PM
Facing is trimming the ends of the headtube or bottom bracket shell so that they are square and parallel.

Tapping is cutting threads like on the insides of the bottom bracket shell.

Chasing is cleaning up existing threads by rerunning a tap through them.
re: What are facing, tapping and chasing a bb or headtube?guido
Mar 2, 2002 8:03 PM
Spoke Wrench speaks the truth, Sempi. The reason for doing this is to ensure that these two critical parts fit well onto the frame, so that the bike will handle well and transfer pedaling energy efficiently to the rear wheel.
All things you must do to Italian framesspookyload
Mar 2, 2002 11:17 PM
As good as they make their frames, you would think they could do this before shipping them. If your Colnago came chased, tapped, and faced, thank you local importer because Colnago sends them out of the factory full of paint.
All things you must do to Italian framesfuzzybunnies
Mar 3, 2002 6:13 AM
also need to do this with american bikes, or any bike where you notice paint in the bb threads or around the inside of the head tube. Russ
Only sometimes,TJeanloz
Mar 3, 2002 7:58 AM
Most American builders ship their frames ready-to-build. I can't think of an American custom builder or factory who ships bikes that need to be faced and chased. Italian frames usually take an hour or so of "frame prep" before they're ready to build. This includes not only facing and chasing, but checking and re-aligning. The only exception to this that I know of is Mondonico/Torelli, who do all the frame prep in the USA before they send them out to dealers.
One differenceNessism
Mar 3, 2002 2:45 PM
I'm not defending the Euro builders but most of these frames come overseas on boats. The time from mfg to build up can amount to several months or even more if they sit at some distributers warehouse. If the frames were faced before shipment they might rust.
Of course, they could always apply some form of rust preventitive.