Author Topic: Nomad Mk3 Rohloff. Owners Guide re Transmission Chain Tensioning via Eccentric.  (Read 183 times)

naffy

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So I tightened the chain for the first time on my Mk3 Nomad. Simple enough, all seems good. I used hand feel on the degree of tightening, not having a torque tool to measure newtons of pressure. Hope that's OK. A very basic observation, the Thorn Guide shows the eccentric without pedals, and I'd originally assumed that this would be a much larger job so was pleasantly surprised to realise that everything could be adjusted with pedals in place! Did wonder whether a note in the Guide might be added to make that point for future purchasers.

Also, can I check if the Eccentric ever needs removing or servicing on a Mk3? I note that there's discussion on that for the Mercury model, though perhaps the Nomad Mk3 is the more sturdy and less maintenance needing option? 

Thought I'd write this on the forum in case its helpful to future readers.

WorldTourer

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Caveat: I have the Nomad Mk 2, but I don't believe that the eccentric is all that different on the Mk 3.

The eccentric does not require servicing, any more than a stem would ever need servicing. That is, the eccentric is just a machined chunk of alumnium. That said, you can destroy the eccentric if you ever turn it so that the screws pierce the thin end of the eccentric. What happens is that the screws destroy the threads for the square taper bottom bracket. This can make it impossible to remove the bottom bracket or install a new bottom bracket.

I learned this the hard way when I tightened the eccentric at the thin end during a tour of the Andes, and my square taper BB cup actually worked its way free and pushed my crank arm off! Not fun. Thank you, Thorn, for selling replacement eccentrics, and I am now much more careful.

Though the eccentric does not require servicing, I still remove it once per year in order to inspect the inside of the frame and ensure there is no rust there.

PH

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Caveat: I have the Nomad Mk 2, but I don't believe that the eccentric is all that different on the Mk 3.
Although it does the same job in the same way, it is a very different design.  The Nomad MKIII follows the Mercury and has a split shell and clamp design, much like clamping a seatpost, so there's no pins to pierce the EBB.  The advice about keeping the narrow section at the top end is reversed and it's best to keep it in the bottom half to impede water ingress.  It is IMO a much better design, there are no indents for the set screws to fall into allowing smaller more accurate adjustments.
I think when Thorn went for this on the Mercury they overestimated how tight it needed to be, hence the first design using four bolts and the new one just two.  I've used this design for a couple of years on the Mercury and ten on a bike before that, I haven't once used a torque wrench on them, you can feel when it's tight enough, just don't over do it.
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Though the eccentric does not require servicing, I still remove it once per year in order to inspect the inside of the frame and ensure there is no rust there.
Yes, and mine gets a smear of copperslip at the same time.
« Last Edit: June 03, 2020, 08:15:00 PM by PH »

WorldTourer

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I stand corrected! Apologies for not answering the OP's question.