Loading the Rohloff Hub

Tom Ace sent this about the Rohloff 14sp hub in another thread:

The more the hub steps torque up or down, the more torque must be
supplied by the arm. The torque arm is unloaded in direct drive,
and is loaded progressively more as gears differ more from 1:1.

[trim] Rohloff only has lower gears than
a Shimano 8, not higher. Rohloff low is 0.279, Shimano 0.527.
Rohloff high is 1.467, Shimano 1.615.

In low gear, the Rohloff steps torque up by 1/0.279 = 3.59.
The torque on the arm is 2.59x the input torque at the cog.

In low gear, the Shimano steps torque up by 1/0.527 = 1.898.
The torque on the arm (or washers) is 0.898x the input torque.

Even if you choose chainring and cog to get the same effective low
gear with both hubs, there will be more torque on the Rohloff arm.

Tom Ace

Rohloff published gearing limits. For instance, with a rider up to
100kg, the crank and sprocket can be 38/16. Here is an extract from
the Rohloff FAQ on the subject:

******
Smallest permittable sprocket ratios

The sprocket ratio on the Rohloff SPEEDHUB 500/14 (e.g. 42/16)
converts the slow rotational speed at the crank into a fast rotational
speed at the sprocket and reduces the input torque for the Rohloff
SPEEDHUB 500/14 in the same proportion.

To prevent overstraining the hub, a minimum sprocket ratio of 2.35
must be used.
With the available sprockets these minumum ratios are achieved by:
40/17, 38/16, 36/15 and 32/13.
This resembles a derailleur transmission of 22/34. Larger chainrings
can be used without exceptions.

Attention!
If mounted on a tandem or if the rider weighs over 100kg, the
following sprocket ratios must not be undercut: 34/13, 38/15, 40/16,
42/17.
-- from the Rohloff FAQ
******

Andy Blance of Thorn (key British tandem and touring bike makers for
the transworld camping crowd) has hinted that he thinks these limits
are so conservative that people might take it on themselves to exceed
the ratio of 2.35.

Let me stress, for the protection of my warranty, that 38/16 gives
three gears under my Shimano Nexus 38/20 system, and I neither need to
nor expect to break the rules to get up my home stretch hill. The
Shimano gives 7.9kph at 60rpm in its lowest gear, and the Rohloff's
four lowest gears give 5.6, 6.3, 7.2 and 8.2kph at 60rpm. These are
calculated with different sized tyres on real-life bikes; i.e. not a
theoretical comparison of like with like. (I'd be happy to publish a
gear-inch comparison table if anyone wants it, or give people copies
of my spreadsheet which automates the comparisons.)

We've discussed this before and the consensus was that one can very
likely break the rules and get away with it, basically on the Blance
argument that no one (except perhaps Chalo) is strong enough to exceed
the limits of the box.

But I would be interested in seeing a number put on it. Let's posit a
100kg rider precisely, borderline by the Rohloff standard. What about
a crankwheel/sprocket setup of 33/16, a ratio of 2.063?
A ratio too far, or just right to climb stairs?

A few years ago a fellow in a Mercedes dicing with me on the road had
to go bush in a rough median strip when a pair of truckies in front of
us became playful; I spun my wife's Volvo estate out on the road, not
a scratch on it. The Mercedes guy, ten grand's worth of panel and
paintwork necessary on his car, wasn't all grateful to have survived
what could have been a much nastier incident if I hadn't given him
plenty of room to blunder around: "See what you've done to my ****ing
Merc." I looked him straight in the eye and said, "If you can't afford
a new one, you should drive slower." Extreme opinions in this thread
will have to be filtered through the knowledge that a Rohloff hub
spoked up in a nice rim comes to c1300USD -- not a piece of equipment
one trashes lightly, or for trivial experimentation.

******
Straws in the wind department:
Further to the discussion Clive and I had the other day about the
prevalence of Magura HS33 hydraulic rim brakes on German-made bikes, I
now notice that German manufacturers have a decided predilection for
42/17T chain setups on Rohloff bikes. I wonder if this is because they
think their customers are all oversize baumeisters, or if the makers
are rule-conscious, or if they know something I don't (and, much less
likely, that Andy Blance doesn't) and are trying to avoid warranty
claims.

Andre Jute
Speculatin' while I wait for my frame-quote to come in

"Andre Jute" wrote in message
...

But I would be interested in seeing a number put on it. Let's posit a
100kg rider precisely, borderline by the Rohloff standard. What about
a crankwheel/sprocket setup of 33/16, a ratio of 2.063?
A ratio too far, or just right to climb stairs?

Are you considering this for your new bike, or just playing?

I now notice that German manufacturers have a decided predilection for
42/17T chain setups on Rohloff bikes. I wonder if this is because they
think their customers are all oversize baumeisters, or if the makers
are rule-conscious, or if they know something I don't (and, much less
likely, that Andy Blance doesn't) and are trying to avoid warranty
claims.

I'd say they're staying within spec of anybody, and they don't need to do
otherwise.

Andy Blance is building bikes for people carrying large amounts of luggage
up steep hills on bad roads. Really tiny gears become relevant then. But for
normal road use, the 20" or lower bottom gear you're getting from even the
conservatively geared rohloff is entirely fine. And if it isn't fine, due to
lack of strength, gearing down past the warranted limits won't be a problem
either.

Andre Jute wrote:

Andy Blance of Thorn (key British tandem and touring bike makers for
the transworld camping crowd) has hinted that he thinks these limits
are so conservative that people might take it on themselves to exceed
the ratio of 2.35.

Let me stress, for the protection of my warranty, that 38/16 gives
three gears under my Shimano Nexus 38/20 system, and I neither need to
nor expect to break the rules to get up my home stretch hill. The
Shimano gives 7.9kph at 60rpm in its lowest gear, and the Rohloff's
four lowest gears give 5.6, 6.3, 7.2 and 8.2kph at 60rpm. These are
calculated with different sized tyres on real-life bikes; i.e. not a
theoretical comparison of like with like. (I'd be happy to publish a
gear-inch comparison table if anyone wants it, or give people copies
of my spreadsheet which automates the comparisons.)

We've discussed this before and the consensus was that one can very
likely break the rules and get away with it, basically on the Blance
argument that no one (except perhaps Chalo) is strong enough to exceed
the limits of the box.

But I would be interested in seeing a number put on it. Let's posit a
100kg rider precisely, borderline by the Rohloff standard. What about
a crankwheel/sprocket setup of 33/16, a ratio of 2.063?
A ratio too far, or just right to climb stairs?

I have long wondered (though I bought my own Rohloff hub before they
were approved for tandem use) why a rider up to 220 pounds is limited
to 38/16 gearing, while _two_ riders up to 220 pounds each are only
limited to 40/16. It doesn't make much sense to me. _All_ riders
over 220 lbs. are cleared to use gearing only 5% higher than the limit
for the lightest riders? How does that work?

I chose, for reasons of my own that I have long forgotten, to use
44/16 gearing on my Rohloff-equipped bike. If 38/16 really is a
prudent limitation for an average-sized rider, I'd reckon that 44/16
for a 350-pound rider with 205mm cranks is pushing well past the
limits of safety. But now that Rohloff have issued a spec, I'm well
within it. And it's not hypothetical; I have ridden my Rohloff bike
long and hard enough to expose any weakness in the gearbox. I don't
ride like I'm _trying_ to break it, but I sure as hell don't baby the
thing.

To me that suggests that there is a generous safety margin applied to
the Rohloff Speedhub, and it would not be a problem for people of
ordinary size who ride with a normal amount of finesse to use lower
primary gearing than specified by Rohloff. How low? Reckon the
torque production of a strong and indelicate 100kg racer, compare your
own physique and riding habits, and apply a conversion factor. You'll
violate the Rohloff warranty, but you'll more that likely be just
fine.

Chalo

On Nov 13, 11:51*pm, Chalo wrote:
Andre Jute wrote:

Andy Blance of Thorn (key British tandem and touring bike makers for
the transworld camping crowd) has hinted that he thinks these limits
are so conservative that people might take it on themselves to exceed
the ratio of 2.35.

Let me stress, for the protection of my warranty, that 38/16 gives
three gears under my Shimano Nexus 38/20 system, and I neither need to
nor expect to break the rules to get up my home stretch hill. The
Shimano gives 7.9kph at 60rpm in its lowest gear, and the Rohloff's
four lowest gears give 5.6, 6.3, 7.2 and 8.2kph at 60rpm. These are
calculated with different sized tyres on real-life bikes; i.e. not a
theoretical comparison of like with like. (I'd be happy to publish a
gear-inch comparison table if anyone wants it, or give people copies
of my spreadsheet which automates the comparisons.)

We've discussed this before and the consensus was that one can very
likely break the rules and get away with it, basically on the Blance
argument that no one (except perhaps Chalo) is strong enough to exceed
the limits of the box.

But I would be interested in seeing a number put on it. Let's posit a
100kg rider precisely, borderline by the Rohloff standard. What about
a crankwheel/sprocket setup of 33/16, a ratio of 2.063?
A ratio too far, or just right to climb stairs?

I have long wondered (though I bought my own Rohloff hub before they
were approved for tandem use) why a rider up to 220 pounds is limited
to 38/16 gearing, while _two_ riders up to 220 pounds each are only
limited to 40/16. *It doesn't make much sense to me. *_All_ riders
over 220 lbs. are cleared to use gearing only 5% higher than the limit
for the lightest riders? *How does that work?

I chose, for reasons of my own that I have long forgotten, to use
44/16 gearing on my Rohloff-equipped bike. *If 38/16 really is a
prudent limitation for an average-sized rider, I'd reckon that 44/16
for a 350-pound rider with 205mm cranks is pushing well past the
limits of safety. *But now that Rohloff have issued a spec, I'm well
within it. *And it's not hypothetical; I have ridden my Rohloff bike
long and hard enough to expose any weakness in the gearbox. *I don't
ride like I'm _trying_ to break it, but I sure as hell don't baby the
thing.

To me that suggests that there is a generous safety margin applied to
the Rohloff Speedhub, and it would not be a problem for people of
ordinary size who ride with a normal amount of finesse to use lower
primary gearing than specified by Rohloff. *How low? *Reckon the
torque production of a strong and indelicate 100kg racer, compare your
own physique and riding habits, and apply a conversion factor. *You'll
violate the Rohloff warranty, but you'll more that likely be just
fine.

Chalo- Hide quoted text -

- Show quoted text -

Going low for better climbing ability is fine, but how low of a top
gear do you want?
I mean at their minimum gearing, using the top gear and 100 RPM, what
is your top speed?

Rohloff has said they are developing a second version of
the Speedhub, smaller and lighter, but still 14 gears
(slightly larger range though).

Details (including availability date) are not finalized, but
word is that it probably won't be approved for tandem use.

http://thelazyrandonneur.blogspot.co...-speedhub.html
http://www.radfahren.de/modules.php?...ticle&sid=3100

Tom Ace

On Nov 14, 9:20*am, "
wrote:
On Nov 13, 11:51*pm, Chalo wrote:





Andre Jute wrote:

Andy Blance of Thorn (key British tandem and touring bike makers for
the transworld camping crowd) has hinted that he thinks these limits
are so conservative that people might take it on themselves to exceed
the ratio of 2.35.

Let me stress, for the protection of my warranty, that 38/16 gives
three gears under my Shimano Nexus 38/20 system, and I neither need to
nor expect to break the rules to get up my home stretch hill. The
Shimano gives 7.9kph at 60rpm in its lowest gear, and the Rohloff's
four lowest gears give 5.6, 6.3, 7.2 and 8.2kph at 60rpm. These are
calculated with different sized tyres on real-life bikes; i.e. not a
theoretical comparison of like with like. (I'd be happy to publish a
gear-inch comparison table if anyone wants it, or give people copies
of my spreadsheet which automates the comparisons.)

We've discussed this before and the consensus was that one can very
likely break the rules and get away with it, basically on the Blance
argument that no one (except perhaps Chalo) is strong enough to exceed
the limits of the box.

But I would be interested in seeing a number put on it. Let's posit a
100kg rider precisely, borderline by the Rohloff standard. What about
a crankwheel/sprocket setup of 33/16, a ratio of 2.063?
A ratio too far, or just right to climb stairs?

I have long wondered (though I bought my own Rohloff hub before they
were approved for tandem use) why a rider up to 220 pounds is limited
to 38/16 gearing, while _two_ riders up to 220 pounds each are only
limited to 40/16. *It doesn't make much sense to me. *_All_ riders
over 220 lbs. are cleared to use gearing only 5% higher than the limit
for the lightest riders? *How does that work?

I chose, for reasons of my own that I have long forgotten, to use
44/16 gearing on my Rohloff-equipped bike. *If 38/16 really is a
prudent limitation for an average-sized rider, I'd reckon that 44/16
for a 350-pound rider with 205mm cranks is pushing well past the
limits of safety. *But now that Rohloff have issued a spec, I'm well
within it. *And it's not hypothetical; I have ridden my Rohloff bike
long and hard enough to expose any weakness in the gearbox. *I don't
ride like I'm _trying_ to break it, but I sure as hell don't baby the
thing.

To me that suggests that there is a generous safety margin applied to
the Rohloff Speedhub, and it would not be a problem for people of
ordinary size who ride with a normal amount of finesse to use lower
primary gearing than specified by Rohloff. *How low? *Reckon the
torque production of a strong and indelicate 100kg racer, compare your
own physique and riding habits, and apply a conversion factor. *You'll
violate the Rohloff warranty, but you'll more that likely be just
fine.

Chalo- Hide quoted text -

- Show quoted text -

Going low for better climbing ability is fine, but how low of a top
gear do you want?
I mean at their minimum gearing, using the top gear and 100 RPM, what
is your top speed?- Hide quoted text -

- Show quoted text -

According to Harric Cyclery Rohloff hub info page and its gear
calculator, the range with a 38x16 gear is 93" to 18" with 700x28
tires. So your top gear is 39x11 or 42x12 or 53x15. Low is 24x34.
At 100 RPM in top gear, 93", you are going 25 mph.

On Fri, 14 Nov 2008 09:45:20 -0800 (PST), "
wrote:

On Nov 14, 9:20*am, "
wrote:
On Nov 13, 11:51*pm, Chalo wrote:





Andre Jute wrote:

Andy Blance of Thorn (key British tandem and touring bike makers for
the transworld camping crowd) has hinted that he thinks these limits
are so conservative that people might take it on themselves to exceed
the ratio of 2.35.

Let me stress, for the protection of my warranty, that 38/16 gives
three gears under my Shimano Nexus 38/20 system, and I neither need to
nor expect to break the rules to get up my home stretch hill. The
Shimano gives 7.9kph at 60rpm in its lowest gear, and the Rohloff's
four lowest gears give 5.6, 6.3, 7.2 and 8.2kph at 60rpm. These are
calculated with different sized tyres on real-life bikes; i.e. not a
theoretical comparison of like with like. (I'd be happy to publish a
gear-inch comparison table if anyone wants it, or give people copies
of my spreadsheet which automates the comparisons.)

We've discussed this before and the consensus was that one can very
likely break the rules and get away with it, basically on the Blance
argument that no one (except perhaps Chalo) is strong enough to exceed
the limits of the box.

But I would be interested in seeing a number put on it. Let's posit a
100kg rider precisely, borderline by the Rohloff standard. What about
a crankwheel/sprocket setup of 33/16, a ratio of 2.063?
A ratio too far, or just right to climb stairs?

I have long wondered (though I bought my own Rohloff hub before they
were approved for tandem use) why a rider up to 220 pounds is limited
to 38/16 gearing, while _two_ riders up to 220 pounds each are only
limited to 40/16. *It doesn't make much sense to me. *_All_ riders
over 220 lbs. are cleared to use gearing only 5% higher than the limit
for the lightest riders? *How does that work?

I chose, for reasons of my own that I have long forgotten, to use
44/16 gearing on my Rohloff-equipped bike. *If 38/16 really is a
prudent limitation for an average-sized rider, I'd reckon that 44/16
for a 350-pound rider with 205mm cranks is pushing well past the
limits of safety. *But now that Rohloff have issued a spec, I'm well
within it. *And it's not hypothetical; I have ridden my Rohloff bike
long and hard enough to expose any weakness in the gearbox. *I don't
ride like I'm _trying_ to break it, but I sure as hell don't baby the
thing.

To me that suggests that there is a generous safety margin applied to
the Rohloff Speedhub, and it would not be a problem for people of
ordinary size who ride with a normal amount of finesse to use lower
primary gearing than specified by Rohloff. *How low? *Reckon the
torque production of a strong and indelicate 100kg racer, compare your
own physique and riding habits, and apply a conversion factor. *You'll
violate the Rohloff warranty, but you'll more that likely be just
fine.

Chalo- Hide quoted text -

- Show quoted text -

Going low for better climbing ability is fine, but how low of a top
gear do you want?
I mean at their minimum gearing, using the top gear and 100 RPM, what
is your top speed?- Hide quoted text -

- Show quoted text -

According to Harric Cyclery Rohloff hub info page and its gear
calculator, the range with a 38x16 gear is 93" to 18" with 700x28
tires. So your top gear is 39x11 or 42x12 or 53x15. Low is 24x34.
At 100 RPM in top gear, 93", you are going 25 mph.

Dear Russell,

Sheldon has a calculator for Rohloff (and other internal gear hubs):
http://sheldonbrown.com/gears/internal.html

Putting in 700x28, 100 rpm, 38x16, and mph at 100 rpm for Rohloff
gives this table:

mph
28.3
24.9
21.9
19.3
17.0
14.9
13.2
11.6
10.2
9.0
7.9
6.9
6.1
5.4

Cheers,

Carl Fogel

On Nov 14, 12:36*pm, wrote:
On Fri, 14 Nov 2008 09:45:20 -0800 (PST), "





wrote:
On Nov 14, 9:20*am, "
wrote:
On Nov 13, 11:51*pm, Chalo wrote:

Andre Jute wrote:

Andy Blance of Thorn (key British tandem and touring bike makers for
the transworld camping crowd) has hinted that he thinks these limits
are so conservative that people might take it on themselves to exceed
the ratio of 2.35.

Let me stress, for the protection of my warranty, that 38/16 gives
three gears under my Shimano Nexus 38/20 system, and I neither need to
nor expect to break the rules to get up my home stretch hill. The
Shimano gives 7.9kph at 60rpm in its lowest gear, and the Rohloff's
four lowest gears give 5.6, 6.3, 7.2 and 8.2kph at 60rpm. These are
calculated with different sized tyres on real-life bikes; i.e. not a
theoretical comparison of like with like. (I'd be happy to publish a
gear-inch comparison table if anyone wants it, or give people copies
of my spreadsheet which automates the comparisons.)

We've discussed this before and the consensus was that one can very
likely break the rules and get away with it, basically on the Blance
argument that no one (except perhaps Chalo) is strong enough to exceed
the limits of the box.

But I would be interested in seeing a number put on it. Let's posit a
100kg rider precisely, borderline by the Rohloff standard. What about
a crankwheel/sprocket setup of 33/16, a ratio of 2.063?
A ratio too far, or just right to climb stairs?

I have long wondered (though I bought my own Rohloff hub before they
were approved for tandem use) why a rider up to 220 pounds is limited
to 38/16 gearing, while _two_ riders up to 220 pounds each are only
limited to 40/16. *It doesn't make much sense to me. *_All_ riders
over 220 lbs. are cleared to use gearing only 5% higher than the limit
for the lightest riders? *How does that work?

I chose, for reasons of my own that I have long forgotten, to use
44/16 gearing on my Rohloff-equipped bike. *If 38/16 really is a
prudent limitation for an average-sized rider, I'd reckon that 44/16
for a 350-pound rider with 205mm cranks is pushing well past the
limits of safety. *But now that Rohloff have issued a spec, I'm well
within it. *And it's not hypothetical; I have ridden my Rohloff bike
long and hard enough to expose any weakness in the gearbox. *I don't
ride like I'm _trying_ to break it, but I sure as hell don't baby the
thing.

To me that suggests that there is a generous safety margin applied to
the Rohloff Speedhub, and it would not be a problem for people of
ordinary size who ride with a normal amount of finesse to use lower
primary gearing than specified by Rohloff. *How low? *Reckon the
torque production of a strong and indelicate 100kg racer, compare your
own physique and riding habits, and apply a conversion factor. *You'll
violate the Rohloff warranty, but you'll more that likely be just
fine.

Chalo- Hide quoted text -

- Show quoted text -

Going low for better climbing ability is fine, but how low of a top
gear do you want?
I mean at their minimum gearing, using the top gear and 100 RPM, what
is your top speed?- Hide quoted text -

- Show quoted text -

According to Harric Cyclery Rohloff hub info page and its gear
calculator, the range with a 38x16 gear is 93" to 18" with 700x28
tires. *So your top gear is 39x11 or 42x12 or 53x15. *Low is 24x34.
At 100 RPM in top gear, 93", you are going 25 mph.

Dear Russell,

Sheldon has a calculator for Rohloff (and other internal gear hubs):
*http://sheldonbrown.com/gears/internal.html

Putting in 700x28, 100 rpm, 38x16, and mph at 100 rpm for Rohloff
gives this table:

* mph
*28.3
*24.9
*21.9
*19.3
*17.0
*14.9
*13.2
*11.6
*10.2
* 9.0
* 7.9
* 6.9
* 6.1
* 5.4

Cheers,

Carl Fogel- Hide quoted text -

- Show quoted text -

Your table is for 700x38 tires. Not 700x28. My 25 mph in a 93 gear
inch was based on 90 rpm. Not 100. 100 rpm gets you 27.7 mph.

Per Clive George:

Andy Blance is building bikes for people carrying large amounts of luggage
up steep hills on bad roads. Really tiny gears become relevant then. But for
normal road use, the 20" or lower bottom gear you're getting from even the
conservatively geared rohloff is entirely fine. And if it isn't fine, due to
lack of strength, gearing down past the warranted limits won't be a problem
either.

I'm about 100kg.

On my old Rohloff, I flirted briefly with 32t on the front; but
quickly went to 38.

Dunno what the gear inches was with 32, but 38's lowest gear is
plenty low for anything I climb.
--
PeteCresswell

On Nov 14, 4:59*am, "Clive George" wrote:
"Andre Jute" wrote in message

...

But I would be interested in seeing a number put on it. Let's posit a
100kg rider precisely, borderline by the Rohloff standard. What about
a crankwheel/sprocket setup of 33/16, a ratio of 2.063?
A ratio too far, or just right to climb stairs?

Are you considering this for your new bike, or just playing?

Just playing. 38x16 will already give me three gears to a third under
my present lowest gear. But I've been around engineers so long I've
picked up one of their worst habits, asking about the best gear, "Now
isn't this vastly overengineered?"

Andre Jute
Spreadsheet man