Chachi wrote:
> I can understand that answer, thank you. I'm also hoping that someone with
> specific knowledge about the Speedhub will answer the following...
>
> The bike I just built up is a Surly Karate Monkey with horizontal dropouts
> and International Standard disk brake mounts. I think the currently
> installed torque arm is fugly.
>
> Is it wise to use the Rohloff OEM2 axle plate in lieu of the torque arm on
> this frame? I'm not so much concerned about the disk brake mount since the
> bike is built like a tank and meets the Rohloff stated requirements. I'm
> more concerned about the horizontal dropouts.
You're right to be concerned about the horizontal fork ends, because
depending on where you set the axle, the distance from the axle to the
disc brake mount will vary. The OEM2 mount is intended for use with
vertical dropouts, where there's a fixed distance betwixt the axle and
the lower disc mount.
This might work, but would probably limit your usable range of axle
positions in the fork ends.
> Are the direction and magnitudes of the forces so significant that the
> torque might move the axle in the dropout?
Not likely.
> Which direction might the axle move, forward or back?
The axle's torque varies in direction, going one way in high gear and
the other way in low gear. I don't see how the axle could actually move
back, though due to the chain tension.
The risk is that the axle could _rotate_ causing the axle nuts to loosen
up, if the OEM2 axle plate doesn't have a snug grip.
> The hub I have is a "TS" or Touring Special with solid axle and nuts (no
> quick release).
Dan Burkhart wrote:
>
> The torque transmitted to the axle shaft is inversely proportional
> with respect to the input torque as it is to the hub shell. While
> input torque is multiplied to the hub shell most in the lowest gear,
> it is multiplied most to the axle shaft in the highest gear.
That's true of hubs such as the SRAM that have direct drive in the
middle of the range.
It's not true of the Rohloff, though. With the Rohloff, direct drive is
11th out of 14 gears.
Top gear is 1.467:1, while bottom gear is .279:1, a much larger gear ratio.
See:
http://sheldonbrown.com/gears/internal
Sheldon "Rohloff" Brown
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