my last hybrid, came with a cheap steel triple, I replaced with with a 50-34 compact double cheap FSA crank but continued to use a 7 speed rear and chain. I was using friction thumb shifters (nice old Suntour alloy ones from the mid 80s), so I first changed cassettes to one that put the big ring in the MIDDLE of the chainline, and then I put spacers on the small ring so it was farther over, more like old school 2x7 spacing instead of 2x10-speed narrow chain spacing. I used the 34 ring strictly as a granny gear, and otherwise treated the bike as a 7-speed on the 50T. in the 34T I could only use the lowest 3-4 cogs but thats all you want in granny gear anyways. it actually worked surprisingly well. my low gear was a 34:32, it worked out like this....

[TABLE="class: mytable"]
[TR]
[TD="class: c0n, bgcolor: #444444, align: center"][SUB]front[/SUB][SUP]rear[/SUP][/TD]
[TD="class: c1n, bgcolor: #AAAAAA, align: center"]14[/TD]
[TD="class: c2n, bgcolor: #AAAAAA, align: center"]16[/TD]
[TD="class: c3n, bgcolor: #AAAAAA, align: center"]18[/TD]
[TD="class: c4n, bgcolor: #AAAAAA, align: center"]21[/TD]
[TD="class: c5n, bgcolor: #AAAAAA, align: center"]24[/TD]
[TD="class: c6n, bgcolor: #AAAAAA, align: center"]28[/TD]
[TD="class: c7n, bgcolor: #AAAAAA, align: center"]32[/TD]
[/TR]
[TR]
[TD="class: c0n, bgcolor: #AAAAAA, align: center"]50[/TD]
[TD="class: c1n, align: center"]98.2[/TD]
[TD="class: c2n, align: center"]85.9[/TD]
[TD="class: c3n, align: center"]76.4[/TD]
[TD="class: c4n, align: center"]65.5[/TD]
[TD="class: c5n, align: center"]57.3[/TD]
[TD="class: c6n, align: center"]49.1[/TD]
[TD="class: c7n, align: center"]43.0[/TD]
[/TR]
[TR]
[TD="class: c0n, bgcolor: #AAAAAA, align: center"]34[/TD]
[TD="class: c1n, align: center, bgcolor: #808040"]66.8[/TD]
[TD="class: c2n, align: center, bgcolor: #808040"]58.4[/TD]
[TD="class: c3n, align: center, bgcolor: #808040"]51.9[/TD]
[TD="class: c4n, align: center, bgcolor: #C0C080"]44.5[/TD]
[TD="class: c5n, align: center"]38.9[/TD]
[TD="class: c6n, align: center"]33.4[/TD]
[TD="class: c7n, align: center"]29.2[/TD]
[/TR]
[/TABLE]