My 640 came with modified (lower) gearing. It has 15-44, so quite low. While excellent in the dirt, it doesn't like to go much over 60 mph / 100 kph! Not sure what rpm (can't remember) but it is revving high and some vibration is more noticeable than normal.
I primarily ride it from home on backroads, searching gravel and dirt, but wouldn't mind a little less buzzy on the pavement (running DOT knobbies and won't change until they are worn out - already have two of the same waiting to go on). I might have to ride 100 KM's one way to get to the dirt / gravel goodness...
One day I hope to ride the Divide (portions thereof) from Calgary AB to Moab, then backtrack to join up with the TAT heading west to Oregon, then home through WA / ID / BC. It would be nice to do it all at once, but life dictates this to be done in stages. Might try to transport bike part ways or heaven forbid, ride more pavement than desired to quickly get to the starting point / hurry home at the end.
With these parameters in mind, what say you inmates in the know?
Should I go to a 16 or 17 tooth front if I keep the 44 (being frugal... the 44 is a supersprox and in great shape. The front is starting to hook so will need to be replaced this spring. Need to check the chain.) Sounds like I will have to either modify or replace the chain guard if I go up to a 17; will I need to also get a longer chain / flip the blocks?
Thanks for your help / opinions in advance.