With a chainring smaller than the back cog
, it's not going to be very useful.
Holy Cow!
You're right, that's the worlds smallest chainring! LOL!
I guess you're expected to ride in 8th gear all the time, spinning like a mad man! I counted 18 teeth on that chainring which means you need an even smaller cog to get some useful gears. I don't believe Shimano makes a 9 tooth cog and their smallest is 16! So using Sheldon's calculator, here's what I got!
Inches: (21 cog, 18 ring, 170 cranks, Nexus 8, 305 tire)
8th gear --- 24.5
7th gear --- 21.5
6th gear --- 18.5
5th gear --- 15.1
4th gear --- 12.9
3rd gear --- 11.3
2nd gear --- 9.8
1st gear --- 8.0