External bearing Bottom Bracket question

[gregcasa]

I just recently purchased an LX M580 crank with external bearings. I happened on to Park tool’s web site and they mentioned preparing the frame by “Facing” the bottom bracket before mounting the bottom bracket.

My question is, is this necessary? Does anyone have any information on this? My bike is about two years old.



Thanks!

[artmichalek]

Facing is done to ensure that the surface of the edge of the bb shell is perfectly perpendicular to the center axis. Typically, this is only an issue with new frames that weren't faced at the factory. Yours was probably faced when the bike was built up.

[gregcasa]

Facing is done to ensure that the surface of the edge of the bb shell is perfectly perpendicular to the center axis. Typically, this is only an issue with new frames that weren't faced at the factory. Yours was probably faced when the bike was built up.Thank you artmichalek for the information.
My old bottom bracket is the cartridge type do you feel it still was faced by the MFG and it should be fine to upgrade? BTW the bike is made by Giant.
Thank you in advance.

[boudreaux]

Facing is done to ensure that the surface of the edge of the bb shell is perfectly perpendicular to the center axis. Typically, this is only an issue with new frames that weren't faced at the factory. Yours was probably faced when the bike was built up.I would not take that as a given.Many aren't