Originally Posted by
sjanzeir
And you're right! So, unless I have ready access to a brick-and-mortar shop that's willing and able to let me try different things and see what works before I buy (which is impossible where I live) - it's all a crap shoot...
If you have a working 2x system you can use it to figure out the gear range you need (assuming that range is somewhere within the existing 2x system), then use that knowledge and a
gear calculator to choose a chainring.