[Closed] Rohloff hub gearing question

Rohloff have calculated that the maximum torque, that the hub will reliably withstand, is slightly more than could be produced by two world class athletes on a tandem using a 38 tooth chainring and a 16 tooth sprocket

Which is 17.2" gear inches on a 26" bike.

which is the same as 32:22 on a three ring/cassette set up.

EDIT: DOh, I mean 22:32! 😉

As low as having 22:32 as lowest gear

But not having a chainring/cogatio of less than 2.4

Look on sheldon brown !

I run either 34x13 or 32x13 with a Rohloff.
1st gear with 32x13 is 1.6metres.

Put the numbers in here to see how it compares with what you've got now.
http://sheldonbrown.com/gears/internal.html

1.6metres.

bloody europeans!

what's that in pounds, shillings and pence eh?

FWIW, [s]I run mine on a 29er at 36:20, which at 14.6" is obviously "illegal", but it's not exploded in a flaming ball of ostriches yet.[/s]

Im talking crap again. I run my SS 36:20, but my rohloff 36:16, which is 18.3"

Druidh - the recommendations for the alfine will be for extreme cases - why not try downgearing it a bit? especially if you are a spinner rather than a masher it should be fine.

I had my 8sp downgeared way low for the puffer and it was fine 22 / 18 IIRC

TJ - I can't use an "inner" ring due to the weird BB. That leaves me with the smallest possible middle ring - currently 32T. There is a "special" 30T ring that might work though.
[img] [/img]
That would give me 18.7" on the current sprocket and as low as 17.1" on a 24T. Still wondering if that is enough though. Salsa are going as low as 15.9" on the Mukluk.*

Edit: * Actually it's 17.7" but it [i]would[/i] be 15.9" on a 26" tyre which is what has been discussed on this thread

doesnt the Nexus 23T fit?
http://www.sjscycles.co.uk/shimano-23t-sprocket-for-nexus-geared-hubs-prod23995/

Might need to tweak chainline though.

Hmmmmmmmmmmmmmmmmmm

another option would be to get a custom rear sprocket made then I guess. weld a chainring off a ordinary cassette to a alfine after cutting the middle out. all steel so should be fairly easy

SA ones fit as well I think

How about [url= http://www.tritoncycles.co.uk/m5b328s177p8745/STURMEY_ARCHER_HSL_Series_Sprockets/RS_GB/23541 ]this?[/url] SA 25 tooth sproket - I am 99% sure they fit

I think the 25T sprocket looks like this...[img] [/img]

whereas it has to look like this...[img] [/img]
(but with more teeth, obviously 🙄 )

Thi is a 17 SA one and it appears to be the same centre as the nexus and to be dished

[img] [/img]

From Sheldon Brown

Most current internal-gear hubs take 3-splined sprockets, interchangeable among brands. These sprockets are available from various sources from 13-24 teeth, though some hubs can't accept the smallest sprockets.

It is also fairly easy to modify any Shimano cassette sprocket that doesn't have a built-in spacer. These are available from 14-34 teeth. Shimano cassette sprockets have the same internal diameter as those used with internal gear hubs, but have 9 splines instead of 3. With a suitable grinder, 6 of the splines need to be removed, and the corners of the remaining three rounded off. A thin spacer washer may also be needed, because the cassette sprockets are a bit thinner than the stock sprockets.

Officially the Rohloff is 2.38:1 for the lowest, this gives you a range of 0.279 to 1.467 from whatever your chainring/cog/wheel/tyre calculates out to. On a 29er running a 700x56 tyre that works out at 19.1 to 100.7 gear inches. This gives a low which is 13.2% lower than the Alfine low on the same setup.

Though that's if you're gearing the Alfine at 32/22 or 1.45:1 some wil lclaim that's too low for the Alfine and will damage the hub.