> BobT wrote:
>
>>I'm thinking about building a commuter bike using the Rohloff 14 speed hub.
>>I've seen the Thorn frames with an eccentric bottom bracket shell for chain
>>tensioning. Is this a better approach than using a standard bottom bracket
>>shell and the Rohloff chaing tensioner device?
>
Chalo replied.
>
> Yes, but the best alternative is probably using a bike with Rohloff OEM
> adjustable dropouts.
>
> An eccentric BB is rather heavy and adds a point of likely mechanical
> failure.
"Likely"? Haven't had a lick of trouble with mine. I've worked on lots
of tandems with eccentric bottom brackets, and have never seen any
serious problems with any that use the simple grub screw system as Thorn
does.
It's true that the wedge type sometimes gets stuck if normal maintenance
is neglected.
> Its main advantage over sliding dropouts is a cleaner
> appearance.
The sliding dropouts would appear to me to be at least as "likely" a
failure point as an eccentric bb.
With the sliding dropouts you need to worry about getting them set
evenly or the wheel will wind up crooked...not a big issue, but not an
issue at all with an eccentric.
With an eccentric you also gain an option of vertical adjustability,
which may be of value to some riders.
An eccentric bottom bracket also permits fine-tuning for perfect
chainline. Given that the Rohloff 54 mm chainline is not all that
common, this feature can be quite desirable. Straight chainline is,
after all, one of the chief benefits of internal gear hubs.
Sheldon "Happy Thorn Raven Owner/Dealer" Brown
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