I'm trying to convert an old city bike (https://archive.trekbikes.com/us/en/2010/trek/navigator10wsd#/us/en/2010/trek/navigator10wsd/details) for my middle-aged mother who did not do any sports so far. There are a lot of slopes in our town, so I want the gear ratio to be as "easy" as possible.
As you can see in the link, the bike has a 1x 42t front chainring and the cassette goes up to 34t.
How would you do it? The following is what I think:
I believe 34t is ok, but 42t is too much. I looked for other 1x systems but no one sells a 1x chainring with 22t or 24t.
Then I decided to buy a 2x or 3x system with a smallest chainring of 22 or 24t and fixing it to that lowest chainring using a front derailleur and limit screws. (You may ask why am I not installing a full 2x/3x system with gear levers and cables: I really do not think she will need the bigger chainring, and there is no routing for the front derailleur cable. If she starts to ride a lot and needs that second chainring I may think about it.)
Do you see any problem with my solution? To avoid the chain being not linear when the smallest ring is used in the cassette, is it better to buy a 2x system? (Is smallest chainring of the 2x systems are closer to the right side, compared to 3x systems? I guess that would help to keep the chain linear.)