Chainline question
Posted: Wed Jul 18, 2012 9:16 pm
Hi All,
I am trying to put a compact double (50T/34T) road crank onto my single speed langster frame to make it a 2-speed.
My stock BB is 103mm, and the recommended BB for the compact double is 115mm.
The langster with the 103mm BB has a 42mm chain line, and the reported chain line of the compact double with a 115mm BB is 43.5mm. I do not understand how increasing my BB by 12mm will only change the chain line 1.5mm. Can someone help me understand this?
Also, assuming that the chain line will only increase to 43.5 (and assuming 5mm chain rings spacing it would give 41mm inner ring and 46mm outer ring spacing), does anyone think that this chain line increase will be too much?
Thanks for the advice, it is much appreciated.
Dave
I am trying to put a compact double (50T/34T) road crank onto my single speed langster frame to make it a 2-speed.
My stock BB is 103mm, and the recommended BB for the compact double is 115mm.
The langster with the 103mm BB has a 42mm chain line, and the reported chain line of the compact double with a 115mm BB is 43.5mm. I do not understand how increasing my BB by 12mm will only change the chain line 1.5mm. Can someone help me understand this?
Also, assuming that the chain line will only increase to 43.5 (and assuming 5mm chain rings spacing it would give 41mm inner ring and 46mm outer ring spacing), does anyone think that this chain line increase will be too much?
Thanks for the advice, it is much appreciated.
Dave