Can someone just double check that both my maths and thinking is correct.
According to the SB calculator - my bike which has a 175mm crank; 2.25 rear tires and a single speed 38T x 16t setup - produces approx 62.15 gear inches.
Now from a year of single speed riding I have become stronger on the hills going up but lazy coming down but as I have got used to these conditions, I figure that when I get an Alfine, that I would be happy with about two gears either side of this but obviously three either side is a bonus..
Now the question, if I keep my 38T and get a 20t for the Alfine, it seems as if my gear inches ratio are now from 26.4 to 81.0.
I was hoping to get a bit closer to a range of around 24 gear inches to around 90 gear inches and my maths say I will need a 42T chainwheel if I stick with the 20t sprocket.. whereas that will get me a high gear of 89 gear inches, I would need a 34T chainrin to get a 23.9 gear inches..
Does this seem about right and also is a 42T chainwheel excessive, especially when everyone here seems to be talking about chain rings in the range of 30-34... will I really suffer that much given that I have been used to hills with up to a 8% - 12% incline. The current setup has me spinning out at around 18mph.
Comments, pointers, slaps for being bad at maths - all appreciated..
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Thread: MATHS... a little help please..