Originally Posted by
SquidPuppet
Does this help?
Notice the 110 is a real oddball?
Code:
Bottom Bracket/Spec Actual NDS DS Symmetrical?
Sugino/Tange 68-103 103mm 17mm 18mm Y (+1mm on DS)
Shimano UN54 68-107 108 20 20 Y
Shimano UN54 68-110 111.5 23.5 20 N (+3.5mm on NDS)
Shimano UN54 68-113 114 23.5 22.5 Y (+1mm on NDS)
Shimano UN54 68-115 115.5 24 23.5 Y (+0.5mm on NDS)
Shimano UN54 68-118 118.5 25.5 25 Y (+0.5mm on NDS)
Shimano UN54 68-122 123 27 28 Y (+1mm on DS)
Shimano UN54 68-127 128 30 30 Y
That's helpful and yes, the 110 is the odd asymmetrical length. I wonder if that was produced just for a certain type of crankset that would compensate for the offset somehow.
One measurement that I've started taking is the distance from the pedal crankarm to the downtube, when you have those lined up. There is variation there. Even if you have a good chainline on the right side, the left arm may not be symmetrical to the bicycle body.