Crankset fitting and so on

If this is a picture of the crank you plan on using for your build, you already have a BB.

This is a picture of the crank that I intended to buy, Its a Truvativ Stylo 3.3 Team.

The two piece cranksets from Truvativ, Race Face, Shimano, FSA all come with the bottom bracket. They fit both 73mm and 68mm (with spacers) BB shell widths

I've done a search for an answer on these forums and at BF (it must have been asked before . . . )

I plan to install that Stylo 3.3 on a bike that currently runs square taper (2008 Ibex Alpine 450). I know the "best" procedure would include facing the bottom bracket and chasing the threads. I've seen a quoted price for this service of $50 (treefortbikes).

I'm wondering how good those external faces need to be. I can mic the existing (painted) surfaces for parallelism. I can mount a dial indicator on the current spindle to check for perpendicularity.

Question: what are reasonable tolerances for these measurements?

kenja said:

I plan to install that Stylo 3.3 on a bike that currently runs square taper (2008 Ibex Alpine 450). I know the "best" procedure would include facing the bottom bracket and chasing the threads. I've seen a quoted price for this service of $50 (treefortbikes).

I'm wondering how good those external faces need to be. I can mic the existing (painted) surfaces for parallelism. I can mount a dial indicator on the current spindle to check for perpendicularity.

Click to expand...

$50 seems high to face the BB shell and chase the threads. If you shop around a bit you might find a shop that'll do it for $20. You can probably leave your threads alone, they're likely fine. If there's paint on the faces (there should be at least a ring of clean metal), you're going to have to face. Even if there's no paint, I'd go ahead and face it anyway. It's not just parallelism that matters, you can't have imperfections anywhere along the face that the BB would bear on.