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OEM axel plate in non-Rohloff-specific droput. Is this going to work?

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AlexRa:

The OEM axel plate fits fine in the horizontal drop out on my bike. It’s not a Rohloff specific dropout. But it fits. The bike is a steel frame Surly Cross Check. 
Is there any reason this won’t work and provide the required torque anchoring? 
Keen to do this as it means I could loose the long torque arm. 
(Also I know it will mean I need some other way of achieving chain tension).

Andre Jute:
There's no reason you shouldn't do it if
-- the little ovoid nub on the Rohloff fits in the channel without play
-- there is enough steel there to resist deforming the track end
-- you can arrange chain tension some other way.

The obvious way, on a Thorn forum anyway, to achieve the last requirement is to find an eccentric bottom bracket shell to fit inside the one on the Surly, plus a bottom bracket of small enough diameter to fit the eccentric bottom bracket shell. Otherwise you're going to be up for welding in an oversize bottom bracket shell: ouch.

However, there's another way, often used on bikes with track ends like yours and Shimano Nexus and other hub gearboxes, called a "t-nut", which allows the axle to slide in the track frame-end (what you call a "horizontal dropout"), thereby tensioning the chain. Bernd Rohloff didn't like this, presumably because it didn't meet his engineering standards, but a cyclist in a bind finds a way. I've never seen it done on a Rohloff but I have two other bikes with this arrangement, and it works, albeit not as conveniently and precisely as the expensively over-engineered Rohloff house design for sliding axle hangers, which Rohloff put in the public domain. Rohloff axle nuts are on a low-torque regime, so to provide positive location you might have to rough up the metal on the outside of the track ends a little (not inside the channel).

Note that chain tension, as long as it is on the loose side -- never, ever, on the tight side -- is less critical with a Rohloff than on any other hub gearbox I can think of. You're supposed to motivate a Rohloff with a much slacker chain than people cross-badging from derailleurs feel comfortable with. You may be able, depending on the exact dimensions of your bike, to arrange a correctly loose chain for all conditions of your fave chains with nothing more than a quick release half-link for even a full link. It seems to me worth a try.

Oh, for a time when even a small boy could understand and remember all the ins and outs of bicycles!

martinf:
If you can't use the horizontal dropout to achieve chain tension, there is a simple bodge that I use on my one remaining full size bike without a Chainglider:

https://surlybikes.com/parts/singleator

The bike on which I use this is an old VTT from the early 1990's designed for derailleurs, it has vertical dropouts and no means of fitting an eccentric bottom bracket without major surgery. I use this as a visitor bike at our island flat. It has a Nexus premium 8 hub, but the system would work just as well with a Rohloff.

I fitted the Singleator pushing up on the chain, with just enough tension to stop the chain falling off. So the extra friction caused by the one Singleator pulley is not really noticeable, in theory it should be half the friction from a normal dérailleur, maybe less as the chain doesn't bend very much.

The downsides for me are :

- one pulley to clean (trivial).
- not possible to fit a Chainglider (a nuisance because this means more chain maintenance).

There are other brands of one-pulley tensioner that would probably work just as well.

Even an old derailleur would work (done this in the past), but it was more of a hassle to set up and clean.

AlexRa:
Thanks everyone.
I guess my question is - is the torque going to bend the drop out? Or is this probably ok? Anyone done /tried anything similar?

mickeg:

--- Quote from: AlexRa on April 30, 2024, 09:43:59 pm ---
The OEM axel plate fits fine in the horizontal drop out on my bike. It’s not a Rohloff specific dropout. But it fits. The bike is a steel frame Surly Cross Check.
Is there any reason this won’t work and provide the required torque anchoring?
Keen to do this as it means I could loose the long torque arm.
(Also I know it will mean I need some other way of achieving chain tension).

--- End quote ---

If I recall correctly, Cross Check is not a disc brake bike, thus the frame is not designed to take the torque from a Rohloff.  If you are in first gear and pedaling hard up a hill, there is a lot of torque on the frame.

I did an internet search for broken bicycle frames with roholff hubs and here is an example:
https://thorncyclesforum.co.uk/index.php?topic=14014.0

Dan had a good post on that thread with reference to Rohloff site:

--- Quote from: Danneaux on December 13, 2020, 02:50:04 am ---...
...

--- Quote ---How exactly does a Rohloff increase torque anyway?
--- End quote ---
The Rohloff's torque reaction arm or tab serves to counter the forward torque applied to the hub under drive. The internal gearing of the hub also multiplies torque on the tab, so there is additional stress applied to the portion of the frame where the torque arm or tab is attached/contained. Rohloff provide a good explanation here:
https://www.rohloff.de/en/service/handbook/speedhub/assembly/torque-anchoring#c26000

Best,

Dan.

--- End quote ---

Rohloffs have been around for much longer than bike disc brakes, but disc brakes also put a lot of torque on the frame, so there have been other options created to mount the hub on disc brake hub frames.  In your case the torque arm is the only option if the frame was not designed for the torque.

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