Originally Posted by
nomadmax
If I read your post correctly, your low gear is 34 x 34. On an unladened bike thats a pretty low gear. I don't know your age, fitness level or the climbs you're having difficulty with but there's probably more gains to be made thru fitness rather than additional low gearing. That said, depending on the bike, you may be able to install a 30/46 crank without a derailleur change.
I agree that the best way to get lower gears is to decrease the size of your chainrings. Then your cogs will be closer together than if you increased the size of the cassette.
Of course the way to get fitter is to climb hard in whatever gear is necessary to allow that. If you're at your best long climb effort and your cadence is below about 78, IME you need lower gears. If you do get fitter and can climb faster, you might outgrow your cassette and want a smaller one, or just have an extra cog below what's necessary. That's my preference because things go wrong.
It's not that hard to figure what gearing you should have. Go to one of your challenging climbs with your current rig. Climb at what you think is your appropriate aerobic effort and note your speed. Enter a gear/cadence/speed calculator and and keeping in mind that speed and your desired cadence, play around with chainring and cog teeth. This is a simple one:
https://www.machars.net/bikecalc.htm I like a long climb cadence in the lower to mid-80s, but everyone's different.
At 75, my climbing gear became 26 X 30.