I don't own a campag pista crankset, but this is something I have wondered : Is the campag pista crankset forging essentially virtually the same as a nuovo record forging? I know that pista spiders lack lips for a second chainring, but more importantly, are the flats for the BB spindle set at a different offset within the right-hand crankarm, causing the crank to ride higher or lower on a given 2-degree tapered spindle?
http://www.campyonly.com/
The spindle lengths involved are : left cup spindle cup right 68-ss-120 : 112 mm spindle 17 - 3.5 - 68 - 3.5 - 20 68-p-120 : 109 mm spindle 17 - 3.5 - 68 - 3.5 - 17
70-ss-120 : 113 mm spindle 17 - 3.5 - 70 - 3.5 - 19 70-p-120 : 109 mm spindle 16 - 3.5 - 70 - 3.5 - 16
So changing from road to track with italian will move the crankset 2 mm towards the frameset.
Now, first of all, there are no laws preventing Frejus from shipping their track bikes with a road bottom bracket. They might even have realized a discount if they are ordering bottom brackets in bulk, and it might save them time and money because they might only need a single type of jig in their shop to make both road and track bikes.
If you can estimate how far "off" the present setup is from ideal, then you can probably pick the correct bottom bracket from the table above, based on the "right" offset measurements.
If you are using a modern symmetric road bottom bracket (not campagnolo), an easy way to convert from Classic Campagnolo road dimensions to modern symmetric dimensions, is to add 2-3 MM to the classic dimensions. If you look at the road dimensions in the table above, the left side is 2-3mm shorter than the right. So, a 112mm BSC campagnolo become a 115 BSC symmetric. A 113mm italian campagnolo becomes a 115 Italian symmetric BB. I think this is true for all BB's in the classic era.
- Don Gillies
San Diego, CA, USA