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#41
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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 |
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#42
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Hub Gears: no need to scoffjaw the warranty
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 |
#43
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Hub Gears: no need to scoffjaw the warranty
"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 |
#44
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Hub Gears: no need to scoffjaw the warranty
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#45
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Hub Gears: no need to scoffjaw the warranty
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 |
#46
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Hub Gears: no need to scoffjaw the warranty
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#47
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Hub Gears: no need to scoffjaw the warranty
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 |
#48
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Hub Gears: no need to scoffjaw the warranty
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#49
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Hub Gears: no need to scoffjaw the warranty
"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 |
#50
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Hub Gears: no need to scoffjaw the warranty
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 |
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