Re: [CR] Campy Pista BB question

Mark,

The latter BB - i.e. the onewith the 111mm spindle, will five you a chainline that is larger by 1mm. The total tread will be 2mm larger. Based on my own experience, I would expect a 43mm chainline with the 111mm spindle and a 42mm chainline with the 109mm. In practical terms, I've found no difference between the two, but as a philosophical consideration, I prefer a perfect chainline whenever possible.

So, here is how I would choose between the two:

1) Tread. (I.e. "Q Factor") The 2mm difference might be meaningful to you, although we're probably talking about the difference between 130 and 132mm, or something like that.

2) Clearance. Depending on the configuration of your chain-stays, you might need the extra 1mm of clearance (per side) afforded by the 111mm spindle.

3) Chain Line. Discussed above. BTW, I would sugget measuring the actual chain line at teh rear, rather than relying on a table, becasue I have seen many inacuracies, even in "reliable sources".

4) Will the bike also be ridden on the road? If so, the rifled cups might be preferrable.

5) Weight? The thin wall cups might be a few grams lighter.

6) Caché. The rifled cups are more expensive and desireable.

I hope this helps :-) If you're not as obsessive about Bottom Brackets as I am, you might flip a coin, or use item #6 as your guide.

Fred Rednor - Arlington, Virginia (USA)