Rohloff great ratios on 20" wheels - Bottom gear.

[somebloke]

Basically, using a Rohloff 14 hub gear, what chain ring and sprocket sizes would be required to get a bottom gear on a 20" wheel equivalent to 22 chainring & 32 sprocket on a normal derailleur system with 26" wheel?
Looking to buy a Circe tandem but need to be sure the gears are low enough to cope with big hills. I also need to be sure this will give a high enough top gear.
Grateful for any info. Thanks

[squeaker]

Have a play here. You might also need to check what size Rohloff sprockets are available.

HTH

[PH]

Rohloff do a 13T sprocket for small wheels, unfortunately it's the only one that isn't reversible, so not such good value. As suggested above, use Sheldon calculator to find the chainring to go with it, something like a 48 should do.

I also need to be sure this will give a high enough top gear.

The range is around 500%, that is the top gear is 5 times higher that n=the bottom one, if you're looking for a 20" bottom gear you'll have around a 100" top, enough for most people.
Bear in mind that 11th is direct drive, noticeably the most efficient, it's worth a bit of compromise to set this as the most used gear.

[somebloke]

Thank you for these replies. Encouraging & informative.

[LWaB]

I know a lady who has a 48 x 13 Rohloff on her skinny-tyred Moulton. Running a 15t reversible cog means the chainring has to be too big. The 13t cog has a slightly wider chainline than the reversible cogs.

[Cunobelin]

Depends on how far you want to push it!

There are some ridiculous ratios out there on tandems and recumbents

I have 5 Rohhloffs with various configurations, but the most extreme is a 34t / 85 t Schlumpf on the front and a 14t rear on a 20" wheel with 150 mm cranks

[LWaB]

Rohloff doesn't make a 14t cog.

[Cunobelin]

Rohloff doesn't make a 14t cog.

Sorry- just recounted and should be 15 T

It was stock when I bought the bike