There shall be some discrepancies in the charts. Some have undergone SAE-to-metric conversions and back. Others have been calculated by other means. Running the same calculation repeatedly MAY return slightly variant results. PHP has trouble with division; more consistant results being sought. Gear range is the highest gear ratio divided by the lowest. Chain-wrap is the difference in slack chain between the largest and smallest gear combos; figures are listed in parentheses after the gear range.
Note the following:
- A standard 11-36 cassette has a range of 327% (25)
- The same with 11-42 cogs is 382% (31)
- The above on a DD3 or Sachs hub is 710% (31)
- An 11-46 Cassette is 418% (35)
- The above on a DD3 hub is 779% (35)
- An 11 - 52 Cassette yields 472% (40)
- The above on a DD3 hub is 873% (40)
- An Alfine 11 hub has 409% (0)
- A Rohloff 500/14 14 speed hub spans 526% (0)
- A front span of 24T to 42T yields 175% (18)
- 24T to 53T is 221% (29)
- 24T to 60T is 250% (36)
- 16T to 42T gives 263% (26)
- 16T to 53T gives 331% (37)
- 16T to 60T gives 375% (44)
- A Schlumpf Mountain Drive single disc yields 250% (0)
- With 34T to 53T it gives 390% (19)
- 34T to 60T yields 441% (26)
- A Pinion p.18 18 speed crank/gearbox spans 627% (0)
Note also: internally geared hubs are not designed for the torque delivered by extremely low gearing. Running a Schlumpf Mountain Drive voids the warranty on the Rohloff and the Alfine 11, and will pull gears out of their press-fits and strip the teeth off in the DD3.
Reckon on a safe minimum of thirty gear inches on an IGH. A late addendum: some Alfine and Rohloff bikes (prebuilt) come with lowest gears below 20 inches; as low as 18.