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Folding Bikes Discuss the unique features and issues of folding bikes. Also a great place to learn what folding bike will work best for your needs.

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Old 08-19-08, 09:22 PM   #26
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Though I think you'd be hard pressed to create such an issue with a 3 speed IGH like a DD (just like I doubt you'd be able to create an issue of cross chaining with a 3 cog cluster).

Does that fit the bill?
Works for me. Thanks.
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Old 08-20-08, 11:58 AM   #27
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The world record for cycling around the world was set using a Rohloff hub.
The oldest standing cycling record I'm aware of is now in its 69th unbroken year. Britian Tommy Godwin’s single year mileage total: 75,056 miles on a Raleigh bicycle with Sturmey-Archer AF four-speed hub, 1939.

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Old 08-20-08, 12:52 PM   #28
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The oldest standing cycling record I'm aware of is now in its 69th unbroken year. Britian Tommy Godwin’s single year mileage total: 75,056 miles on a Raleigh bicycle with Sturmey-Archer AF four-speed hub, 1939.

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"Godwin dismounted his bike and spent weeks learning how to walk again before going off to war in the RAF."

http://en.wikipedia.org/wiki/Tommy_G...list_born_1912)
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Old 08-20-08, 01:16 PM   #29
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Yup, and Godwin's record is equal to cycling around the world several times.

Wonder how many derailleurs would be needed to do the same job. (Although I'd be surprised if it was the same hub gear all the way through.)
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Old 08-25-08, 08:53 AM   #30
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Although I'd be surprised if it was the same hub gear all the way through.
Color yourself surprised.

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Old 08-25-08, 09:02 AM   #31
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Originally Posted by Sixty Fiver View Post
...and older SA hubs tend to be far better made than later production models.
The late Sheldon Brown praised the quality of the new Taiwanese manufactured Sturmeys.

One item, though: the old hubs used oil, which weeped out. Replentishing it provided an ongoing supply of fresh, low drag lubricant. The new hubs use a synthetic grease. Good stuff, last a long time, there's no weekly oiling - but there's a little more drag with this higher viscosity lubricant.

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PS - It's very easy to drill and tap (1/4-20) the alloy shell of a new SRF-3 for an old-school oiler.

Last edited by tcs; 08-28-08 at 11:15 AM.
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Old 08-25-08, 09:40 AM   #32
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Do small gains or losses in efficiency really matter to commuters, multi-modal commuters, and leisure riders?
Amazingly enough, drivetrain efficiency doesn't seem to matter to sport riders and even most racers.

That Berto/Kyle report you quoted rediscovered some 110+ year old cycling wisdom concerning the inefficiency of relatively small cogs. Example: a 52/15 ratio (~94 gear inches) is measureably more efficient than a 38/11 (also ~94 gear inches). Despite a real efficiency difference, nearly all modern sport riders happily equip their bikes with the smallest available gear train components to save a few meaningless ounces!

The Berto/Kyle study wasn't perfect, but has been called by many the best science to date on bicycle drivetrain efficiency. I'd love to see them test again and include the Alfine, I9 and SA8 hubs.

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Old 08-26-08, 03:37 AM   #33
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It's all to do with the polygon angles of the cog. I believe it was once recommended that around 23 teeth upwards was optimum.
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Old 08-26-08, 06:30 AM   #34
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But is that the trade off that is made. I don't see there really being a continuum with efficiency at one end and reliability at the other. I don't think these variables are even remotely related. In fact although I am far from being an engineer and am only a bodging dabbler, I feel sure that there are two quite different variables here and that the continuums (plural?) range from reliability -> unreliability and a quite separate one of efficiency -> inefficiency. I'm pretty tired just now so maybe I missed something here.
I don't know the answer either, but have been led to think maximum efficiency calls for precision whereas maximum reliability demands greater tolerances. Which isn't to say you can't have both, only that it's more expensive to achieve both. This belief comes from pieces I've read over the years offering broad-brush comparsions of the differences in engineering philosophy between German cars (e.g. VW, Porsche, Audi, BMW) and Japanese cars (Toyota, Nissan, Lexus, Acura). The common thread of these articles was that the precision engineered German cars require frequent adjustment to remain at peak performance and to avoid excess wear, whereas the greater tolerances built into Japanese cars require far less frequent adjustment and the components last much longer. I'm just repeating what I read long ago ... with the caveat that these articles were not in scientific journals but in periodicals.

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P.S. If those anecdotes have a grain of truth, then I will take the slop if the tradeoff is only a slight drop in efficiency and a large gain in reliability. I hope the Alfine is the Toyota Camry of IGHs.

Last edited by timo888; 08-26-08 at 06:39 AM.
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