I was under the impression that Shimano could only handle up to 28t in the back? I assume I might need a longer chain to do that also so probably looking at $100.

Lately as I've gotten stronger I haven't been going lower than 34/25 combo when climbing which is 35.8 gear inches which is obviously still a lot lower than the 41 gear inch of 39/25 combo. But in a lot of the shorter climbs I had been staying in the big ring and even big ring/large cog combo of 50/32 is 41 inches. I like to climb out of the saddle so in theory I should be ok on most of my rides for now but when I get onto some longer more sustained climbs I may be hurting