Community > Rohloff Internal Hub Gears

changing sprocket,uses for the old one?

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ledburner:
For anyone changing to a new sprocket, I neeed an old one.
Please see my post in wanted if you dont have a use for it (posted16/1/1).
Thx
Ledburner...

Danneaux:
None available from me at the moment, Ledburner, but I'm surely interested in your plans for same.

Best,

Dan. (...who saw your call on the "Wanted" board and is by now burning with curiosity)

ledburner:
The plan is to make a dual rear sprocket.  half step between ratios. Replace the chain tensioner with a  short cage deraileur,
I believe this is possible by carefully selecting 2 close sprockets.
I tried this with double chain rings. It worked but changes were too slow.
(The chain ring didn't have ramps etc to speed up the shifts.)
 Note, A eighth to quarter turn at the front will change the dual rear faster than a half turn Of the cranks, with a double-chainset set at the front.

I am currently on a triple chain set on the front, the inner ring is a chain catcher for poor shifts.
I dont really have 42 usable gears.28 will be enough!
.

Danneaux:
Thanks! I figured!  ;)

When I first considered a Rohloff, I also pondered a half-step setup, but one using a single sprocket and dual chainrings (I prefer half-step gearing on my randonneur bikes). The steps and progression came out pretty nicely with a 2-tooth difference between the 'rings, but it would require both a front derailleur and a chain tensioner, where your scheme would eschew the front mech in favor of a rear derailleur instead of a tensioner.

In practice, I have found the single 'ring and cog on my Nomad to be "enough" for my needs primarily because my most-used gears are the same (in gear-inches) as my most-preferred half-step derailleur combos on my rando bikes. :)

Looking forward to seeing the result and all good wishes on sourcing the cogs you need.

Best,

Dan.

martinf:

--- Quote from: ledburner on January 17, 2018, 11:45:12 pm ---The plan is to make a dual rear sprocket.  half step between ratios. Replace the chain tensioner with a  short cage deraileur,
I believe this is possible by carefully selecting 2 close sprockets.
I tried this with double chain rings. It worked but changes were too slow.

--- End quote ---

My aim was to extend a limited gear range, not to get finer gear steps, but I came to the same conclusion with my "touring" Brompton.

First I fitted double chainrings and 5-speed hub. Later I fitted two sprockets (13 and 19) on the 5-speed hub and dispensed with the double chainrings. I needed to grind the raised tabs of the 19T sprocket, after that it fitted OK on the driver of the 5 speed hub with a standard Brompton 13T sprocket and slim spacer.

Two rear sprockets shift much quicker, and this setup is substantially lighter (weight counts, because I carry the folded Brompton). Downside is that the small 13T sprocket clogs sometimes in mud or snow, and the special pulleys on the Brompton rear derailleur are more hassle to clean than a front derailleur.

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