Is there a word for the range of "difficulty to pedal"?

Question

On an older bike I had 21 gears with two blocks of chainrings (one at the pedals and one in the back). Currently I have 8 gears with a shimano system where the chain does not hop on different cogwheels (as I just learned an "internally geared hub").

On my old bike the first gear was easier to pedal than my current first gear and the 21st gear was harder to pedal than my current 8th gear. Obviously this has to do with the gear setups, but it got me wondering: Is there a word for this range of "difficulty to pedal"? Theoretically one could add more gears in between current ones just leading to more subdivisibility but not more "range".

(not well versed in english bike terms, you see I am at a loss for words here...)

My motivation is: I would like a bigger range but do not need more gears (in the sense of subdivisibility).

Answer 1

For Internal Gearing
Internal or hub gears can be expressed as a ratio of how many times the rear wheel turns for each time the crank rotates once. The ratio is determined by the number of teeth on the sprocket (the term for the gear on the back of a single speed or hub geared bicycle), the number of teeth on the chainring and the way the hub is designed to work for each speed.

For example, a bike with a 50 tooth chainring and a 30 tooth sprocket using a bendix 2 speed red band would have a low gear of 2.3 and a high gear of 3.4. The rear wheels spins 2.3 times in the low gear for every rotation of the crank and 3.4 times in the high gear for every rotation of the crank.

Sheldon Brown has a calculator with a wide range of options for calculating ratios.
For a visual reference:
From www.cyclinguk.org
The chart assumes the sprocket and chainring is a 1 to 1 ratio.

For External Gearing

Here is some common terminology so that we can zero in on the words you need.

Based on the contents of the question I'm assuming an external gear system so focusing on that.
This is just the basics of gear ratios. I'm not going to get into crank length and wheel size. Sheldon Brown has a detailed article on gear ratios with a nice chart.

Cassette: The cassette is a stack of cogs. Most bikes will have 5 to 11 cogs. Each cog has a number of teeth.

Chainrings: A bike will have 1 to 3 chainrings. Each chainring has teeth

Gear ratio describes the relationship between the number of teeth on the chainrings and the cogs. if the chainring has 50 teeth and the chain is on the cog with 11 teeth then 50/11= 4.55 so, for every revolution of the pedals the rear wheel will turn 4.55 times. This gear would take more force to turn than a gear ratio of .5 which would require very little force but give very little forward motion. A gear ration of .5 would be good for climbing steep hills.

A high gear gives you more revolutions of the rear wheel per revolution of the pedals than a low gear.

Back to the question

On my old bike the first gear was easier to pedal than my current first gear and the 21st gear was harder to pedal than my current 8th gear.

On your old bike first gear had a lower gear ratio than your current bike and the 21st gear was a higher gear ratio than your current 8th gear.
If you knew the ratios for the different gears you could describe exactly how much difference there is between the bikes.

Answer 2

David D did a great job explaining the gear ratios. Sometimes calculations include the lever arm of the driven wheel and/or the crank arm you pedal, so I pulled out some of the contextual vocab from Sheldon Brown, in case you find the same ideas under other names.

• Development/Rollout "Development is the distance the bicycle travels for one crank revolution, and is usually measured in meters." Note that this considers the diameter of the wheel, but not the crank arm.
• Gear Inches is more or less Development in imperial units.
• Gain Ratio is an invention of Sheldon Brown himself, and is the ratio between the distance the end of the crank arm travels and the distance the bicycle travels. Critically, this includes the lever arms of the driven wheel and the crank you are pedaling on. Gear ratio does not consider that part of the drive train. In an ideal world, this is how every bicycle transmission would be described.