Gain Ratios, Chain Inches... Help me understand Sheldon!

[One-eyed Sailor]

I've tried but I'm slow.
I entered the following for the Ross/Nexus 8 I just completed.

Here are the GR and GI numbers

The intended use is urban/bike path/fire road/pump track kinda stuff.
I just don't understand very well what all the numbers translate to.
Do they match my intended use?

I'll get more miles riding in if it ever quits snowing here. My jobsite is a frozen lake.

I used to love winter but I'm old and grumpy these days

Thanks Rat Bros!

 

[user 35233]

If i understand correctly what you're asking also depends on how hard you push, or wish to. My three speed is more for traveling distance though I roll off-road at any chance and my easiest gear is at about your hardest. Where as my single speed is easier than that because I use it more for tight maneuvers where quick acceleration is needed. Trails sound like the latter but again, it really depends upon your strength and how fast you wanna ride, if i understood your question.

 

[us56456712]

You don’t need that info, it’s a triviality. What I do is find what gearing I like on various bikes 1 ride for what ever purpose. Find a range for what you’re doing, basically all you need is what low gear works and what high gear works. Forget all that stuff about crank arm length and how far the wheel goes in one revolution. That’s useless. I then use the simplest bare bones gear inch calculation. People say gear inch is antiquated and it might be for hot shots, but for the advanced enthusiast this is all you need. Gear inch equals drive wheel diameter in inches times the number of teeth in the chainring (1/2 inch pitch chain) divided by the number of teeth in the rear cog. Don’t worry about measuring the wheel, if it’s say any of the 26 inch wheels just use 26 inches. All measures in inches so measure a 700 c to see how many inches you get. After you figure what works for high and low you can convert any of your bikes to that. You can also convert various wheels, cogs and chainrings to gear inches and see how far they are from what you need before buying parts. A derailleur bike can be used to see what works for you and your purpose and those high/low gears converted to gear inches. Then you can get those on your target bike. I’ve been doing this for a longtime and it works for me. As I age my needs have changed so I have changed the cogs or chainrings to better get what I need. Hot shots fine tune how far a bike travels with each revolution and each gear is chosen by the terrain and their riding style or ability. I’m not there. In my opinion that’s all you need. The number that works, once you have that your set.

 

[user 35233]

True. To be honest I just pick a gear I like, count the teeth and build outward switching cogs if it ain't what I expected. I use something simple like this but really just to visualize it.

I assume "spinnier" is a technical term

 

[MattiThundrrr]

Another good one to remember for the BMX ratios from the chart above is this formula: 2x+2. For a good cruising ratio, take the rear tooth count, multiply by two and add two and you should have a good starting point for cruising on 26" wheels.
For example, (14 tooth cog x2)=28+2=30. Smack dab in the yellow on the chart.
For that Nexus, you might want to find out which gear is a direct drive, and make that your "golden gear"*, or do it with the middle one, so you have equal gears below and above.

*The direct drive gear could possibly be strongest, most durable, most efficient, so it might be best for the hub. I don't know for sure, just how I was thinking...