Hub Gears: no need to scoffjaw the warranty

"Andre Jute" wrote in message
...
Nick Payne wrote:

Seeing that Rohloff are quite happy for their hub to be used on a tandem
with the recommended 2.4:1 front/rear ratio, I had no scruple using a
lower
ratio on my own bike when I took it to Switzerland for two months in
2004. I
used 38/16 with 38x622 tyres, which gave a bottom gear that I found
pretty
useful for comfortably climbing grades up to about 25% with a loaded
bike.
That ratio gave gears from a low of 18 up to about 95 inches.

If you look at the actual hub specs, it nominates a maximum torque of
250Nm
at the crank with the recommended 2.4:1 ratio. With 170mm cranks that's
about 150Kgf on the pedal.

Yeah, that's why I mentioned loaded alpine touring, 'cos I couldn't
instantly think of another example.

Never mind the gear, how do you keep your balance going up a 25% grade
with a loaded bike? Sounds like an argument for credit card touring...

I was down to about 6kph on some of the steeper slopes. Didn't find any
problem with being able to ride at that speed. An altimeter speedo printout
of one of the more extreme climbs he
http://www.users.on.net/~njpayne/bik...d/RigiKulm.pdf, and a
photo taken looking back down the climb he
http://www.users.on.net/~njpayne/bik...d/RigiKulm.jpg.

Nick

Nick Payne wrote:

"Andre Jute" wrote in message
...
Nick Payne wrote:

Seeing that Rohloff are quite happy for their hub to be used on a tandem
with the recommended 2.4:1 front/rear ratio, I had no scruple using a
lower
ratio on my own bike when I took it to Switzerland for two months in
2004. I
used 38/16 with 38x622 tyres, which gave a bottom gear that I found
pretty
useful for comfortably climbing grades up to about 25% with a loaded
bike.
That ratio gave gears from a low of 18 up to about 95 inches.

If you look at the actual hub specs, it nominates a maximum torque of
250Nm
at the crank with the recommended 2.4:1 ratio. With 170mm cranks that's
about 150Kgf on the pedal.

Yeah, that's why I mentioned loaded alpine touring, 'cos I couldn't
instantly think of another example.

Never mind the gear, how do you keep your balance going up a 25% grade
with a loaded bike? Sounds like an argument for credit card touring...

I was down to about 6kph on some of the steeper slopes. Didn't find any
problem with being able to ride at that speed. An altimeter speedo printout
of one of the more extreme climbs he
http://www.users.on.net/~njpayne/bik...d/RigiKulm.pdf, and a
photo taken looking back down the climb he
http://www.users.on.net/~njpayne/bik...d/RigiKulm.jpg.

In the photo it never looks as steep as it really is. That amazing
Ciclosport printout tells the real story. Pity my doctor won't let me
try it... Thanks for those.

Nick

Andre Jute
Green with envy

"Tom Sherman" wrote in message
...
[...]

The upright will probably always be the fastest on very steep climbs.
However, at lesser grades the aerodynamic advantage of the recumbent could
turn the tables, particularly with a professional class rider putting out
close to 400 watts of power. The standing position on an upright creates
considerable drag, even at speeds as low as 20-25 kph.

Recumbents are not any good on even slight climbs. I did not even notice
slight grades on my uprights whereas I do notice every slight upgrade on my
recumbents. There is simply no comparison.

Unfortunately, none of the famous climbs have ever been done in timed runs
by a world class cyclist, trained on a recumbent, on a state of the art
(stiff frame and seat, less than 7.5 kg mass) design. Therefore, this
question remains unanswered.

Oh for Heaven's sakes, recumbent cyclists cannot even began to compete with
upright cyclists in the mountains. Try to get real!
[...]

Regards,

Ed Dolan the Great - Minnesota
aka
Saint Edward the Great - Order of the Perpetual Sorrows - Minnesota

Per :
For example, replacing the 40-tooth front with a smaller 32-tooth
would be begging for trouble, since 32:16 is only 2.00:1, well below
the 2.35:1 minimum front/rear sprocket ratio.

I rode a 32 up front for at least a year.

Now I've got a 38 up there.

215# - but probably pathetically-weak enough that the hub's in no
danger.
--
PeteCresswell

On Fri, 01 Feb 2008 17:10:30 -0500, "(PeteCresswell)"
wrote:

Per :
For example, replacing the 40-tooth front with a smaller 32-tooth
would be begging for trouble, since 32:16 is only 2.00:1, well below
the 2.35:1 minimum front/rear sprocket ratio.

I rode a 32 up front for at least a year.

Now I've got a 38 up there.

215# - but probably pathetically-weak enough that the hub's in no
danger.

Dear Pete,

Just to check, how many rear teeth?

Cheers,

Carl Fogel

Per :
Just to check, how many rear teeth?

16
--
PeteCresswell

On Fri, 01 Feb 2008 20:50:33 -0500, "(PeteCresswell)"
wrote:

Per :
Just to check, how many rear teeth?

16

Dear Pete,

Yikes!

Given the price, glad it lasted.

Cheers,

Carl Fogel

, expatriate Normal person, wrote:
On Jan 31, 10:52 pm, Tom Sherman
wrote:

See http://vitessecycle.com/page.cfm?PageID=66.

Yeah, Koos, that's the guy.

They still sponsor a racing team?

Not sure, since I have not lived in B-N since 1998 and moved away from
central Illinois in 2001.

The upright will probably always be the fastest on very steep climbs.
However, at lesser grades the aerodynamic advantage of the recumbent
could turn the tables, particularly with a professional class rider
putting out close to 400 watts of power. The standing position on an
upright creates considerable drag, even at speeds as low as 20-25 kph.

Unfortunately, none of the famous climbs have ever been done in timed
runs by a world class cyclist, trained on a recumbent, on a state of the
art (stiff frame and seat, less than 7.5 kg mass) design. Therefore,
this question remains unanswered.

Fair enough. I've done a little reading on the subject recently; the
bent, for most people (again from just a little skimming), is admitted
to have speed disadvantage compared to an upright on climbs.

Again, apples to oranges most likely. Not enough data exists at this
point to make definitive judgments.

However, most upright riders climb at a fairly low cadence, and many
stand for much of the time. My statement was to indicate predominant
behavior, not all techniques used. The point remains that the
predominant method of climbing steep grades on an upright is not
suitable for a recumbent, and for a given rider, lower gears are needed
on the recumbent than the upright.

One of the big advantages the upright has, and not only for climbing.
Plus the ability to change back and forth, a very useful thing when
climbing longer hills, something that has become even more effective
with shift-on-the-bars (brifter) controls. Shift up a cog or two for
standing, back down for sitting. From what I've seen, many alternate
because they aren't trained to stand for long periods.

Much the same effect can be had on a recumbent with a variable seat back
angle. Making such a system light and reliable is an area that needs
development.

It should also be noted that for every instance of recumbent
proselytizing, whether in the real world or Usenet, there are many
instances of ignorant and gratuitous recumbent denigration.

Well, bents-- just the machine itself-- tend to be funny-looking--
crank out in front instead of handlebars, for instance, and great big
long chains weaving around. Some are much more gnarly than others, but
even the smoothest don't look like an upright, which of course people
are a whole lot more used to seeing. Then, the various rider
positions, some where the feet look about as high as the head, look
strange to most people. Catching a little grief is part of the deal
with wanting to look/be different.

I find that the main detriment of a recumbent - unwanted attention. That
is why I will almost certainly get an upright for commuting this spring.
Comfort is not too hard to achieve for periods of one-half hour at a time.

--
Tom Sherman - Holstein-Friesland Bovinia
"And never forget, life ultimately makes failures of all people."
- A. Derleth

"Tom Sherman" wrote in message
...
[...]
I find that the main detriment of a recumbent - unwanted attention. That
is why I will almost certainly get an upright for commuting this spring.
Comfort is not too hard to achieve for periods of one-half hour at a time.

Even a stopped clock like Tom Sherman is right twice a day. Most folks do
not ride their bikes for long periods of time. In fact, a half hour to an
hour is about it for most. An upright will serve fine if that is all you are
going to ride. Recumbents are for those who ride for many hours at a single
sitting. They are ideal for week long tours like RAGBRAI.

Regards,

Ed Dolan the Great - Minnesota
aka
Saint Edward the Great - Order of the Perpetual Sorrows - Minnesota

quoth Andre Jute
...Shimano specifically says the chainwheel/sprocket tooth
ration should be between 2.0 and 2.1.

I have never seen this spec for Nexus hubs. I suspect this is related
to the Smover automatic transmission system, not to any limitation of
the Nexus hub itself.

Smover isn't yet available on this side of The Pond, so I have no
experience with this, but as far as the hub itself is concerned,
there's no reason for Shimano or anyone else to object to a high gear
ratio. It's only chain ratios that overstress hubs.

My own Nexus 8 bikes a

http://sheldonbrown.org/raleigh-international 52/19 w/28-622 tyres

(I was running 52/18 when I was using that wheel on my Picchio tandem
for a couple of weeks.)

and:

http://sheldonbrown.org/iro 52/18 w/33-584 tyres

See also: http://sheldonbrown.com/gears/internal

Sheldon "Neck's Us" Brown
+-------------------------------------------+
| My daughter is a fine singer. She's on |
| YouTube singing Dvorak and Mozart: |
| http://tinyurl.com/2wbf3c |
+-------------------------------------------+
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
Useful articles about bicycles and cycling
http://sheldonbrown.com