Single-Speed/Rohloff Dual Personality Bike

[Fred Roses]

I was thinking of building up a bike that could be used around town as a single-speed and on tour
with a Rohloff hub. Seems to me all that I would need are two rear wheels and possibly two chains
(though it would be nice if I could snag the same chain-length for both setups). My preference
would be to use an oversize eccentric bottom-bracket for chain tensioning and perhaps disc brakes.
I suppose I would need to find some neat way of terminating the Rohloff control cables when using
the single speed hub. I would love to get some feedback on whether people think this is a practical
idea and hopefully some suggestions for frame details, braze-ons, and configurations. Thanks for
your help!

 

[Peter]

"Fred Roses" <[email protected]> wrote in message
news:[email protected]...
> I was thinking of building up a bike that could be used around town as a single-speed and on tour
> with a Rohloff hub. cut.... My preference would be to use an oversize eccentric bottom-bracket for
> chain tensioning and perhaps disc brakes. I suppose I would need to find some neat way of
> terminating the Rohloff control cables when using the single speed hub. I would love to get some
> feedback on whether people think this is a practical idea and hopefully some suggestions for frame
> details, braze-ons, and configurations. cut....

Just built a Rohloff expedition bike with disk brakes and though I used a chain tensioner set up in
the end, I seriously considered using a singlespeed Ti frame from On-One that uses an oversized
eccentric BB, mainly because everyone who uses On-one stuff seems to love their gear. I know
several people have used this frame for Rohloff hubs and Brant from On-One is friendly and helpful.
http://www.on-one.co.uk/

The two Rohloff changer cables terminate in a gizmo thats removed complete with the cables remaining
in it by unscrewing a knurled nut ( that wont drop out of the unit when its loose) with your
fingers, so the cables and gizmo could easily be tucked up complete into a waterproof bag or holder
on the frame stay when not required. I use the Rohloff stay to stop the hub revolving and its just a
matter of pulling a pin to the out position to loosen the stay from the frame. Again the pin won't
drop out. Picture of these at: http://www.fastload.net/03/picpages/wheelof.html but be patient as it
may take a while to download. Links to other pics at http://www.fastload.net/03/pages/index.html

Given this I can't see any problems and think you'd probably need only one chain provided the rear
cogs were nearly the same size, as you could make fine adjustments by moving the wheel along the
horizontal dropouts. Using QR's on the wheels I can't see switching taking more than a couple of
minutes. Good luck peter

 

[x]

RE/
>Seems to me all that I would need are two rear wheels and possibly two chains (though it would be
>nice if I could snag the same chain-length for both setups). My preference would be to use an
>oversize eccentric bottom-bracket for chain tensioning and perhaps disc brakes. I suppose I would
>need to find some neat way of terminating the Rohloff control cables when using the single speed
>hub. I would love to get some feedback on whether people think this is a practical idea and
>hopefully some suggestions for frame details, braze-ons, and configurations.

I just did it, but so far haven't tried the SS config - although I've got a cassete-friendly wheel
hanging in the garage..

My frame has an eccentric BB. Initially wanted the Rohloff dropouts, but the builder asked around
and, for some reason, got a negative feeling about them.

I don't see any problem with terminating the shifter. Worst case, just bungee it to the frame with a
little pipe insulation wrapped around it or (preferably IMHO) find a set of grips that go on and off
easily and yank it altogether when converting to SS mode.

I started with V-brakes assuming I wanted minimum weight and maximum simplicty. Converted to Avid
cable discs as soon as I found out that v-brakes like to have a true and well-centered wheel. Also
I missed the feel of discs and wanted my two wheelsets interchangable between this bike and my
"main" bike.

This particular frame didn't come out so well. It's ridable and actually I am getting quite a bit of
enjoyment out of it while my FS is down waiting for a part. But the frame is a little bizarre in
that the setback is about 2.5-3" too far back and I had have a set-forward adapter fabricated to
interface between the seat tube and the saddle post.

However the resulting bike fulfills it's primary purpose for me. By virtue of S&S couplings it can
be disassembled into two wheels, two frame parts, saddle/post and the bars - which will fit in the
rooftop box of my vehicle or any average-size car trunk where I can just sort of forget about it
until an unexpected riding opportunity arises.

When I finally get over having ****** away so much money on this one and find another builder to do
it right the things that I'll revisit are:

1) Eccentric BB vs Rohloff dropouts. I'll revisit this with a prejudice toward the Rohloff dropouts
because the eccentric BB can eat up fore-aft saddle adjustment and also because it looks like it
weighs quite a bit more than the Rohloff dropouts.

2) The Roholff-specific cable stops the current builder put on the seat stays: they save about six
inches of cable housing - which can't weigh much more than the stops themselves.

3) Luggage rack braze-ons: the way it is now, one side's braze-on is buried in
SpeedBone/skewer lever.

4) The reinforcing piece that joins the horizontal chainstay with the seat stay: it keeps the skewer
lever from closing all the way.

5) Down tube/fork crown clearance: currently the little adjustment knobs on the crowns of my Manitou
shock bash up against the frame's down tube and eventually will dent it.
-----------------------
PeteCresswell