Rohloff Dropouts: Anybody using them?

Looks like a fifth chain tensioning alternative:

1) Have the frame built with horizontal dropouts

2) Have the frame built with an eccentric BB

3) Add a derail-type tensioner

4) Swap rings/cogs and hope to get lucky

5) Have the frame built with Rohloff's adjustable dropouts: essentially a vertical dropout with
about a half-inch of fore-aft movement.

The half inch part is what got my attention (actually 28 mm).

If a chain only breaks at every other link (i.e. in one-inch increments) how is a half inch of
adjustment going to be reliable?

In another thread, the idea of a "half link" was mentioned. Sounds like it might be the explaination
if I understood what a "half link" was and how a chain could be sized accordingly.

-----------------------
PeteCresswell

 

(Pete Cresswell) wrote:
> Looks like a fifth chain tensioning alternative:
>
> 1) Have the frame built with horizontal dropouts
>
> 2) Have the frame built with an eccentric BB
>
> 3) Add a derail-type tensioner
>
> 4) Swap rings/cogs and hope to get lucky
>
> 5) Have the frame built with Rohloff's adjustable dropouts: essentially a vertical dropout with
> about a half-inch of fore-aft movement.
>
Van Dessell uses this system, it's a nice setup.
>
> The half inch part is what got my attention (actually 28 mm).

28 mm is over an inch, actually.

> If a chain only breaks at every other link (i.e. in one-inch increments) how is a half inch of
> adjustment going to be reliable?

Even if it was only half an inch, you can fine tune by changing sprocket sizes. A sprocket (either
front or rear) one tooth larger moves the axle forward 1/8 inch (3 mm)

> In another thread, the idea of a "half link" was mentioned. Sounds like it might be the
> explaination if I understood what a "half link" was and how a chain could be sized accordingly.

A half link is a hermaphrodite link, it's half an inch long, has only two rollers. The link plates
are bent, so one end of it connects to an inner link, t'other end connects to an outer link.

There's some confusion in terminology, onacountta some folks think a link is 1/2" long, others
(including me) say a link is one inch long.

Sheldon "Chains" Brown +-----------------------------------------------------+
| It is undesirable to believe a proposition when | there is no ground whatever for supposing it
| true. | --Bertrand Russell |
+-----------------------------------------------------+ Harris Cyclery, West Newton, Massachusetts
Phone 617-244-9772 FAX 617-244-1041 http://harriscyclery.com Hard-to-find parts shipped Worldwide
http://captainbike.com http://sheldonbrown.com

 

Sheldon Brown wrote:

> A half link is a hermaphrodite link, it's half an inch long, has only two rollers. The link plates
> are bent, so one end of it connects to an inner link, t'other end connects to an outer link.

I'd say it's the full link that is the hermaphrodite link.

--
Benjamin Lewis

Although the moon is smaller than the earth, it is farther away.

 

"(Pete Cresswell)" <[email protected]> wrote:
>
> 5) Have the frame built with Rohloff's adjustable dropouts: essentially a vertical dropout with
> about a half-inch of fore-aft movement.
>
...
> If a chain only breaks at every other link (i.e. in one-inch increments) how is a half inch of
> adjustment going to be reliable?

Since the chain is a loop, 1/2" variation between centers equals roughly 1" chain length.

Those dropouts work well, but the added width and forward length can cause heel interference if
chainstay length is short. I was constantly clipping my heels on the dropout mounting plates on my
Van Dessel Buzz Bomb. That was one of the reasons I parted with it.

If your feet are short, or your chainstays are long, then you may have no such problems.

Chalo Colina

 

RE/
>> The half inch part is what got my attention (actually 28 mm).
>
>28 mm is over an inch, actually.

Oops, the dread disease RCI strikes again...

Sounds to me like I'm going to lean on my next builder to go the Rohloff route. What was giving me
reservations was that nobody whose web site I looked at was touting them as a singlespeed solution.
SyCip in particular offers a horizontal drop with adjustment screw (which doesn't allow for a disk
brake)..but doesn't mention the Roholoff drops.

I've got an eccentric BB on my current (failed) frame. It works, but eats into fore-aft saddle
adjustment.
-----------------------
PeteCresswell

 

Sheldon Brown <[email protected]> wrote in message
news:<3E8A719B[email protected]>...
> (Pete Cresswell) wrote:
>
> > In another thread, the idea of a "half link" was mentioned. Sounds like it might be the
> > explaination if I understood what a "half link" was and how a chain could be sized accordingly.
>
> A half link is a hermaphrodite link, it's half an inch long, has only two rollers. The link plates
> are bent, so one end of it connects to an inner link, t'other end connects to an outer link.
>

Is this the same as the 'Offset Links' mentioned on your fixed gear page? And while I think I can
figure out what they ought to look like, do you have a photo online?

Brian "I am Curious (Celeste)" Huntley

 

Sheldon Brown wrote:
> A half link is a hermaphrodite link, it's half an inch long, has only two rollers. The link plates
> are bent, so one end of it connects to an inner link, t'other end connects to an outer link.

Are such things available commercially?

I've made one of these with pliers and a vise to manage a tricky fit with a kid-adapter on my
tandem (fitting the bolt-on secondary BB between stays and bottle studs). My half-link was fairly
crude, though.

Regards,
--
Mark Janeba remove antispam phrase in address to reply

 

"(Pete Cresswell)" <[email protected]> wrote:
: RE/
:>> The half inch part is what got my attention (actually 28 mm).
:>
:>28 mm is over an inch, actually.

: Oops, the dread disease RCI strikes again...

: Sounds to me like I'm going to lean on my next builder to go the Rohloff route. What was giving me
: reservations was that nobody whose web site I looked at was touting them as a singlespeed
: solution. SyCip in particular offers a horizontal drop with adjustment screw (which doesn't allow
: for a disk brake)..but doesn't mention the Roholoff drops.

: I've got an eccentric BB on my current (failed) frame. It works, but eats into fore-aft saddle
: adjustment.

If you're having a custom frame built, why not just set up the geometry so the seat and BB start at
the same extreme so they can be adjusted in parallel. Also, seatposts come with different setbacks.

If you go with the adjustable dropouts, you'd still have the brake adjustment issue (or maybe you're
using a disc?)

I think my preference would be for an eccentric BB, but I was able to get a perfect fit with a half
link and some cog juggling and still ended up with the exact gear range I wanted. I wouldn't mind
some Rohloff dropouts for the purpose of eliminating the torque-arm, though.

- mark

 

Mark Janeba <[email protected]> wrote:
: Sheldon Brown wrote:
:> A half link is a hermaphrodite link, it's half an inch long, has only two rollers. The link
:> plates are bent, so one end of it connects to an inner link, t'other end connects to an
:> outer link.

: Are such things available commercially?

Yes, I got one from Harris Cyclery.

: I've made one of these with pliers and a vise to manage a tricky fit with a kid-adapter on my
: tandem (fitting the bolt-on secondary BB between stays and bottle studs). My half-link was fairly
: crude, though.

At least your method works with any chain. As far as I know you can only buy a half link for the
wider 1/8" chains (so I ended up buying a chain, too).

- mark

 

I writed:

>> A half link is a hermaphrodite link, it's half an inch long, has only two rollers. The link
>> plates are bent, so one end of it connects to an inner link, t'other end connects to an
>> outer link.

Mark Janeba wrote:
>
> Are such things available commercially?

Yes, but only for 1/8" and wider chain. See:

http://sheldonbrown.com/harris/fixed.html#1/8

where they're listed as "offset links."

> I've made one of these with pliers and a vise to manage a tricky fit with a kid-adapter on my
> tandem (fitting the bolt-on secondary BB between stays and bottle studs). My half-link was fairly
> crude, though.

If you started with a normal 1/2" center-to-center item, I would expect that the result would be a
half link with shorter-than-standard pitch. Could work for a low-stress application like a stokid
crank, but I would expect trouble in an adult-powered drivetrain.

Sheldon "To Half And Half Not" Brown +----------------------------------------------------+
| I’m not convinced that this was the right time | to attack Iraq, but I would like to express my
| | support for, and gratitude to U.S. and allied | fighting forces, and to wish them all
| success. |
+----------------------------------------------------+ Harris Cyclery, West Newton, Massachusetts
Phone 617-244-9772 FAX 617-244-1041 http://harriscyclery.com Hard-to-find parts shipped Worldwide
http://captainbike.com http://sheldonbrown.com