rohloff chainline?

I was under the impression that Rohloffs are to be run on a single chainwheel up front?
Don't Rohlofs have 14spds, 500% variation?
rohloff.deindex.phpOpen ↗

Even though the price seems steep (@ $1600Aus), it's comes across as the most logical option for year round MTB XC race use with little maintenace & consumption of parts compared to external cassette & derailuer.

Reports have it that the Rohloff can last through more than one bike, but the price itself is basically a well optioned bike....

(I don't think I've answered you question here, just rambled really....)

till! said:

Ill start off by pointing out Im already confused, but that
isnt necessarily a secret around here ...

Seems rohloff want a 54mm chainline, and that seems freaking
wide to me. So how do you get it?

Ordinarily if you had a road double you would use a 108mm(?)
bb ... and guessing ... a 46mm outer with a 41mm inner? You
can get the BB in 108/113/118mm graduations.

Also, to add further complications, I probably want a 39 - 42t
chainring, and only a single at that ... I can swap the inner
to the outer if I want? There is a fair bit of choice around
130BCD/5-arm, you can get most of the way between 38-56t if
you can swap which side the ring fits?

So I should get a 118mm BB, that would give me a 51mm ring on
the inner, or 56 on the outer, not a 113mm BB, as it would
only give me 51mm on the outer, or worse, 46mm on the inner?

All these numbers have been possibly misinterpreted from
Sheldon Brown's site, but we can safely say it isnt his fault.

I'm running a SRAM/Sachs Spectro S7 internal-gear hub. I've
mounted the dished sprocket in the concave position, giving me
a 55.5 mm chainline.

I'm using a Shimano 104 PCD triple crankset with a single 36T
chainwheel mounted in the outmost position. I find a 110mm
bottom bracket gives me a perfect chainline (to within a mm).

John

Marx SS said:

I was under the impression that Rohloffs are to be run on a single chainwheel up front?

You can, and you probably want to, but that doesnt have much to do with the issue at hand. Actually if you have a real money problem you can get a shlumph(???) mountain drive as well, but that would be another $1600 probably =)

till

"Marx SS" wrote in message...

Quoted message said:

<snip>

Quoted message said:

Even though the price seems steep (@ $1600Aus), it's comes across as
the most logical option for year round MTB XC race use with little
maintenace & consumption of parts compared to external cassette &
derailuer.

<snip>

A bit on the heavy side for normal XC racing, but then I think gears and derailuers add to much weight. ;-) Would be handy for a
muddy Polaris or 24hr.

ParbSS

till! said:

Seems rohloff want a 54mm chainline, and that seems freaking wide to
me. So how do you get it?

Rohloff's marketing folks think this hub is for downhill mountain
bikes, and the 54 mm spec pretty much corresponds to the outermost ring
on a typical MTB triple chainset.

Quoted message said:

Ordinarily if you had a road double you would use a 108mm(?) bb ...
and guessing ... a 46mm outer with a 41mm inner?

That sounds about right.

Quoted message said:

You can get the BB in
108/113/118mm graduations.

Since modern BBs are symmetrical, a 118 would put the outer ring at 51
mm. You'd want a 124 to get to exactly 54 mm. If your cranks use the
traditional square bottom bracket, you can get pretty close to that.
If they're splined, you won't find a BB longer than 118.

Quoted message said:

Also, to add further complications, I probably want a 39 - 42t
chainring, and only a single at that ... I can swap the inner to the
outer if I want?

Yes that's no problem.

Quoted message said:

So I should get a 118mm BB, that would give me a 51mm ring on the
inner, or 56 on the outer, not a 113mm BB, as it would only give me
51mm on the outer, or worse, 46mm on the inner?

All these numbers have been possibly misinterpreted from Sheldon
Brown's site, but we can safely say it isnt his fault.

The 118 bb is only 5 mm longer _on each side_ than the 108, so those
numbers are not correct.

118, as I mentioned above, will put the outer ring at 51 mm.

If you want perfect chainline, you could install 5 3 mm spacers between
the chaining and the crank spider. This will also save you from having
to buy a set of short chainring bolts.

See: http://sheldonbrown.com/harris/singlespeed.html#bolts for a photo
of a similar setup, though in this case the spacers are used to move
the chainline inward.

These spacers are nothing special, they're standard rear-axle spacers,
10 mm inside diameter. Just make sure you get a matched set.

Another way to move chailne to the right is to put a spacer washer
under the right side bottom bracket mounting ring. Sturmey-Archer
sprocket spacers are good for this, 1/16" thick.

Sheldon "http://harriscyclery.com/rohloff" Brown
Newtonville, Massachusetts USA
+-------------------------------------------------+
| One measurement is worth 50 expert opinions |
| --Howard Sutherland |
+-------------------------------------------------+
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 said:

till! wrote:

The 118 bb is only 5 mm longer _on each side_ than the 108, so those
numbers are not correct.

118, as I mentioned above, will put the outer ring at 51 mm.

If you want perfect chainline, you could install 5 3 mm spacers between
the chaining and the crank spider. This will also save you from having
to buy a set of short chainring bolts.

Hmm, thanks for the reply - next time Ill measure from both ends =)

Puzzlingly there seems to be octalink BBs at 121 AND 126mm, at nashbar but only for a 73mm shell, not the 68mm Id more likely want.

The spacers you suggested are probably a better idea, provided I clear the chainstays.

till

till! said:

Sheldon Brown said:

If you want perfect chainline, you could install 5 3 mm spacers
between
the chaining and the crank spider. This will also save you from
having
to buy a set of short chainring bolts.

Hmm, thanks for the reply - next time Ill measure from both ends =)

Puzzlingly there seems to be octalink BBs at 121 AND 126mm, at nashbar
but only for a 73mm shell, not the 68mm Id more likely want.

The spacers you suggested are probably a better idea, provided I clear
the chainstays.

If you're spacing the chainring out, make sure you don't go too close to
the crank arm...

--
BrettS