# Mounting Rohloff disc rotor?



## vikb (Sep 7, 2008)

I mounted a Rohloff disc rotor onto my IGH and realized after the fact that I put it on opposite to the direction of rotation in the Rohloff manual. I'm feeling lazy so I wanted to check with the Rohloff gurus on MTBR to see if the direction of rotation really matters??...


----------



## suba (Jun 25, 2009)

I think it most definitely does....


----------



## -jes (Feb 6, 2011)

It's worth the effort to change it :thumbsup: ........................... just to stop people pointing and laughing at you on the trails 

On a serious note don't chance it.


----------



## estutjaweh (Jan 3, 2008)

I would be more worried with the torque plate/axle/dropout combination!


----------



## finch2 (Nov 13, 2009)

yeah I think it does matter...save yourself more headache later.


----------



## MacB (May 13, 2011)

estutjaweh said:


> I would be more worried with the torque plate/axle/dropout combination!


no I think he's good on that looks like and OEM 2 axle plate and Monkeybone combination, pretty standard and officially Rohloff approved.

I would swap the disc rotor round though


----------



## estutjaweh (Jan 3, 2008)

...not approved in a fork-end dropout though. The skewers apparently dont hold tight enough either unless you crank them on tight (which then apparently leads to shifing problems). 

Vikb:- Have you got a tug nut on the other side or something to eliminate wheel movement? May be an idea.

The other reason for my comment is that the brake must be undone every time you want to remove the rear wheel. That would get on my nerves after a bit.


----------



## vikb (Sep 7, 2008)

estutjaweh said:


> ...not approved in a fork-end dropout though. The skewers apparently dont hold tight enough either unless you crank them on tight (which then apparently leads to shifing problems).
> 
> Vikb:- Have you got a tug nut on the other side or something to eliminate wheel movement? May be an idea.
> 
> The other reason for my comment is that the brake must be undone every time you want to remove the rear wheel. That would get on my nerves after a bit.












Surly Black Ops 1×1 Mountain Bike&#8230; « The Lazy Rando Blog&#8230;

I have an IGH on my Surly Pugsley and it's never bothered me to swing the caliper up when I remove the rear wheel. I do it so infrequently it's hardly worth considering.


----------



## vikb (Sep 7, 2008)

I flipped the rotor around, but looking at it I can't see any reason why it would matter to the hub or the brake caliper which way the rotor was spinning.


----------



## -jes (Feb 6, 2011)

The spines on the rotor are angled towards the force of braking.
I guess this is a mechanical/design element to minimise flexing/rotational movement in the braking surface.


----------



## vikb (Sep 7, 2008)

-jes said:


> The spines on the rotor are angled towards the force of braking.
> I guess this is a mechanical/design element to minimise flexing/rotational movement in the braking surface.


From this thread:

*"As a rule of thumb, you can assume that the tensile and compressive strengths of steel are the same. However, in your example of disc shape, I'd say shear strength will be the limiting factor provided you can keep the disc laterally stable.

And the shear force will be about the same in both shapes so it doesn't matter which way the disc faces."*


----------



## -jes (Feb 6, 2011)

Good find vikb,

Also found this article  where their technical data makes the case for trailing spines but the manufacturer now recommends installing rotors with them facing forward to resolve an issue they experienced with the rotor warping.

MTB rotors are made out of stainless steel rather than steel, looking at this technical paper on stainless steel there a lot of "stuff" to disseminate in there but seems to indicates SS has "high tensile plasticity" and elongates more under tensile forces compared to compression.

I don't suppose it's a huge issue until prolonged high force/drag braking and/or weight come into effect.


----------



## finch2 (Nov 13, 2009)

facing forwards should keep the rotor in tension withthe spokes spreading outwards, instead of encouraging the spokes to fold down... well that's the way I see it anyway.


----------

