T
Tom Sherman
Guest
Andre Jute wrote:
> A concurrent thread on a big gear range made me wonder what width one
> could achieve in hub gears by ignoring the recommended chainring/
> sprocket ratio, which for Rohloff appears to be a fraction under 2.5
> and for the Shimano Nexus 8-speed hub is specifically given as from
> 2.0 to 2.1. I have no idea how long the hubs would survive under
> abusive handling as in some of the examples below. All numbers in gear
> inches.
>
> With a 37-622 tyre and 46-16 gears, the Rohloff Speed Hub would give a
> range from a notch or two below many mountain bikes to pretty well
> beyond what most people could manage on the flat. Fourteen gears in
> gear inches developed:
>
> 22
> 25
> 28
> 32
> 37
> 42
> 47
> 54
> 61
> 70
> 79
> 90
> 102
> 116
>
> Just for comparison, here are the gear inches for the 14 gears of the
> Rohloff with a more reasonable, and possibly permitted (I've seen it
> several times), 42-16 setup. Still a very respectable spread, and
> probably more pleasurable to use:
>
> 20
> 23
> 26
> 29
> 33
> 38
> 43
> 49
> 56
> 64
> 72
> 82
> 93
> 106
>
> Adding the Schlumpf Speed Drive to a Rohloff Speed Hub seems
> unnecessary: it will add only four useful gears at most, the rest
> being duplicated.
>
Why not consider the Schlumpf High Speed Drive [1] that offers a 2.5:1
step-up, as compared to the 1.65:1 step-up of the Speed Drive?
> Okay, let's look at the Shimano Nexus 8-speed hub.
>
> With a 37-622 tyre and the same 46-16 gears as inour first example,
> but in this case even more abusive, the Shimano Nexus 8-speed hub
> combined with the Schlumpf Mountain Drive would give an even wider
> useful spread, 14 unique gears out of 16 covering from a Himalayan low
> gear to 127in to pose with in cafe society. (This covers the entirely
> unreasonable 18 to 123in someone asked for in a concurrent thread, and
> a bit more.)
>
Unreasonable for an upright bicycle, yes.
However, for a recumbent bicycle, that wide gearing range is not at all
unreasonable, but nearer to a necessity. The proper climbing technique
on a recumbent bicycle is unlike that for an upright bicycle, where the
preferred climbing technique of many is to stand and pedal at a
relatively low cadence, while pulling on the handlebars to increase
one's "effective" weight.
Conversely, the proper climbing technique on a recumbent is to use a
very high cadence (e.g. 120 RPM) and to pull back [2] as much as
possible. Trying to use the upright climbing technique will result in
excess lactic acid buildup with the rider then needing to stop or slow
severely to recover.
The (performance oriented) recumbent will also descend faster (where
tight corners or rough surfaces do not limit speed too severely) than
the upright. In particular, on a frontally or fully faired recumbent,
the rider can pedal without increasing drag, so a very high gear can be
used while going downhill.
I have a couple of lowracer bicycles with gear inch range of 19-120
(achieved with a step-up jack-shaft) and a "bodysock" faired long wheel
base recumbent with a range of 15-125 gear inches (achieved with a
triple crank and 3x7 hub). I have found both the lowest and highest gear
ratios on these bicycles useful.
> Gear Direct SMD
> 1 42 17
> 2 51 20
> 3 59 24
> 4 67 27
> 5 79 32
> 6 97 39
> 7 112 45
> 8 127 51
>
> I was speaking to a guy in the parts department at Volvo in Gothenburg
> a few years ago, and when he heard I planted a Chevy mouse motor in
> one of their estates and was now supercharging it and looking to use a
> few gennie Volvo parts, he said thickly, "Doncha tell Warranty. Inna
> flash Warranty turn your ash to grash." (On a tip from this colourful
> fellow I ordered the parts I wanted a lot cheaper from Rolls-Royce
> than from Volvo; they bought them the same place but the Volvo markup
> was higher...) I imagine Shimano will turn one's warranty, and one's
> ass, to grass in a flash if they hear about a 46-16 FR tooth ratio on
> one of their Nexus hubs, when they went to the trouble of printing the
> ratio warning on the cover of the spec sheet.
>
> So let's try 38-18, which at 2.11 recurring is arguably within the
> permitted ratio, and can be built with Shimano's goodlooking and
> reasonably priced own-brand parts intended for the hub gear bikes.
> With the Schlumpf Mountain Drive, that gives 14 unique gears that
> covers everything from loaded goatherding to pretty fast touring:
>
> 31 12
> 37 15
> 43 17
> 49 20
> 58 23
> 71 28
> 82 33
> 94 37
>
> It does look like iconoclasm and scoffjawing the warranty is
> unnecessary. With either the Rohloff or the Nexus/Schlumpf combination
> you can get nicely spaced gear ratios over a very wide operating band.
> The designers of those hubs and geared bottom bracket got it right.
>
> In fact, riding daily in the low rolling hills of West Cork, I find
> 38-19 sets of teeth just right on the Nexus gear hub without the need
> for the Schlumpf geared bottom bracket; it gives me the following gear
> inch development for the 8 gears, perfect for day rides on my
> particular countryside without ever having to push:
>
> 29
> 35
> 41
> 47
> 55
> 67
> 78
> 89
>
Would not a higher gear be useful when drafting trucks downhill?
> Sprockets with any number of teeth you can want are readily available,
> so for another use, say loaded alpine touring, I would not hesitate to
> change the sprocket to give a ratio that is not permitted. I think the
> Nexus hub is a lot sturdier than Shimano lets on, and it is widely
> known that the Rohloff hub is panzer.
>
Of course, one can obtain very low gearing when the Rohloff is used in a
small drive wheel, without violating Rohloff's restrictions. Lacing the
large flange Rohloff hub into an ISO 349-mm hub would be challenging, if
one were to use it on a bicycle such as the Tri-Sled Nitro [3].
[1] <http://www.schlumpf.ch/hsd_engl.htm>.
[2] Clipless pedals with good retention are mandatory.
[3] <http://www.trisled.com.au/nitro.html>.
--
Tom Sherman - Holstein-Friesland Bovinia
"And never forget, life ultimately makes failures of all people."
- A. Derleth
> A concurrent thread on a big gear range made me wonder what width one
> could achieve in hub gears by ignoring the recommended chainring/
> sprocket ratio, which for Rohloff appears to be a fraction under 2.5
> and for the Shimano Nexus 8-speed hub is specifically given as from
> 2.0 to 2.1. I have no idea how long the hubs would survive under
> abusive handling as in some of the examples below. All numbers in gear
> inches.
>
> With a 37-622 tyre and 46-16 gears, the Rohloff Speed Hub would give a
> range from a notch or two below many mountain bikes to pretty well
> beyond what most people could manage on the flat. Fourteen gears in
> gear inches developed:
>
> 22
> 25
> 28
> 32
> 37
> 42
> 47
> 54
> 61
> 70
> 79
> 90
> 102
> 116
>
> Just for comparison, here are the gear inches for the 14 gears of the
> Rohloff with a more reasonable, and possibly permitted (I've seen it
> several times), 42-16 setup. Still a very respectable spread, and
> probably more pleasurable to use:
>
> 20
> 23
> 26
> 29
> 33
> 38
> 43
> 49
> 56
> 64
> 72
> 82
> 93
> 106
>
> Adding the Schlumpf Speed Drive to a Rohloff Speed Hub seems
> unnecessary: it will add only four useful gears at most, the rest
> being duplicated.
>
Why not consider the Schlumpf High Speed Drive [1] that offers a 2.5:1
step-up, as compared to the 1.65:1 step-up of the Speed Drive?
> Okay, let's look at the Shimano Nexus 8-speed hub.
>
> With a 37-622 tyre and the same 46-16 gears as inour first example,
> but in this case even more abusive, the Shimano Nexus 8-speed hub
> combined with the Schlumpf Mountain Drive would give an even wider
> useful spread, 14 unique gears out of 16 covering from a Himalayan low
> gear to 127in to pose with in cafe society. (This covers the entirely
> unreasonable 18 to 123in someone asked for in a concurrent thread, and
> a bit more.)
>
Unreasonable for an upright bicycle, yes.
However, for a recumbent bicycle, that wide gearing range is not at all
unreasonable, but nearer to a necessity. The proper climbing technique
on a recumbent bicycle is unlike that for an upright bicycle, where the
preferred climbing technique of many is to stand and pedal at a
relatively low cadence, while pulling on the handlebars to increase
one's "effective" weight.
Conversely, the proper climbing technique on a recumbent is to use a
very high cadence (e.g. 120 RPM) and to pull back [2] as much as
possible. Trying to use the upright climbing technique will result in
excess lactic acid buildup with the rider then needing to stop or slow
severely to recover.
The (performance oriented) recumbent will also descend faster (where
tight corners or rough surfaces do not limit speed too severely) than
the upright. In particular, on a frontally or fully faired recumbent,
the rider can pedal without increasing drag, so a very high gear can be
used while going downhill.
I have a couple of lowracer bicycles with gear inch range of 19-120
(achieved with a step-up jack-shaft) and a "bodysock" faired long wheel
base recumbent with a range of 15-125 gear inches (achieved with a
triple crank and 3x7 hub). I have found both the lowest and highest gear
ratios on these bicycles useful.
> Gear Direct SMD
> 1 42 17
> 2 51 20
> 3 59 24
> 4 67 27
> 5 79 32
> 6 97 39
> 7 112 45
> 8 127 51
>
> I was speaking to a guy in the parts department at Volvo in Gothenburg
> a few years ago, and when he heard I planted a Chevy mouse motor in
> one of their estates and was now supercharging it and looking to use a
> few gennie Volvo parts, he said thickly, "Doncha tell Warranty. Inna
> flash Warranty turn your ash to grash." (On a tip from this colourful
> fellow I ordered the parts I wanted a lot cheaper from Rolls-Royce
> than from Volvo; they bought them the same place but the Volvo markup
> was higher...) I imagine Shimano will turn one's warranty, and one's
> ass, to grass in a flash if they hear about a 46-16 FR tooth ratio on
> one of their Nexus hubs, when they went to the trouble of printing the
> ratio warning on the cover of the spec sheet.
>
> So let's try 38-18, which at 2.11 recurring is arguably within the
> permitted ratio, and can be built with Shimano's goodlooking and
> reasonably priced own-brand parts intended for the hub gear bikes.
> With the Schlumpf Mountain Drive, that gives 14 unique gears that
> covers everything from loaded goatherding to pretty fast touring:
>
> 31 12
> 37 15
> 43 17
> 49 20
> 58 23
> 71 28
> 82 33
> 94 37
>
> It does look like iconoclasm and scoffjawing the warranty is
> unnecessary. With either the Rohloff or the Nexus/Schlumpf combination
> you can get nicely spaced gear ratios over a very wide operating band.
> The designers of those hubs and geared bottom bracket got it right.
>
> In fact, riding daily in the low rolling hills of West Cork, I find
> 38-19 sets of teeth just right on the Nexus gear hub without the need
> for the Schlumpf geared bottom bracket; it gives me the following gear
> inch development for the 8 gears, perfect for day rides on my
> particular countryside without ever having to push:
>
> 29
> 35
> 41
> 47
> 55
> 67
> 78
> 89
>
Would not a higher gear be useful when drafting trucks downhill?
> Sprockets with any number of teeth you can want are readily available,
> so for another use, say loaded alpine touring, I would not hesitate to
> change the sprocket to give a ratio that is not permitted. I think the
> Nexus hub is a lot sturdier than Shimano lets on, and it is widely
> known that the Rohloff hub is panzer.
>
Of course, one can obtain very low gearing when the Rohloff is used in a
small drive wheel, without violating Rohloff's restrictions. Lacing the
large flange Rohloff hub into an ISO 349-mm hub would be challenging, if
one were to use it on a bicycle such as the Tri-Sled Nitro [3].
[1] <http://www.schlumpf.ch/hsd_engl.htm>.
[2] Clipless pedals with good retention are mandatory.
[3] <http://www.trisled.com.au/nitro.html>.
--
Tom Sherman - Holstein-Friesland Bovinia
"And never forget, life ultimately makes failures of all people."
- A. Derleth
