Need advice: 21 speed to 7 speed
Pardon if I get the terminology wrong. Life long bike rider, but not an informed bike enthusiast.
The bike is an FS Elite AAC 600. Aluminum frame, 21 speed with a DuoTrack 7007 front fork. Seems pretty well made, light, comfortable to ride (I had been riding a very heavy, steel framed Bridgestone MB6). I am not a trail rider. I just bike in and around my neighborhood for excercise, as well as some family bike outings in parks and such.
The left 3 speed shifter is cracked and broken. It will shift from the low (smallest) gear to the mid gear, but it's balky. I'm thinking about doing away with the shifter altogether and turning this into a 7 speed. After having experimented riding using both low and mid gear, it seems that something between the two would be ideal. So, my question is, any tricks to finding a replacement gear of the right size? How are these referred to? By diameter? Number of teeth? Are there any compatability issues?
It looks like all I need to do is remove the grip shift and front derailer hardware, and then change out the existing front gears for a single gear of the right ratio. Am I missing anything?
Thanks in advance for any advice.