i'm looking for a new bottom bracket and i'm having some trouble finding what i'm looking for. right now the chainline works with 103mm spindle. i was going to just go cheap with the shimano un-73 but i can't find anything smaller than 107mm. so basically i'm looking for a 68mmx103mm bottom bracket for fairly cheap. i guess i could buy the un-73 and just replace the spindle? any suggestions?