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Old September 13th 17, 05:13 AM posted to rec.bicycles.tech
Frank Krygowski[_2_]
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Default program to compute gears, with table

On Tuesday, September 12, 2017 at 6:48:12 PM UTC-4, wrote:
On Tuesday, September 12, 2017 at 11:58:38 AM UTC-7, Frank Krygowski wrote:

Didn't Shimano advertise derailleurs as being "9 Speed" when they were precisely
the same geometry as their previous derailleurs?


I'm not sure of that Frank. I think that the angles were improved over time. I know that I have a Campy long arm rear derailleur that doesn't shift as well as a short arm newer model. The way the arms rotate and drop are much better on the short arm. That seems to be my experience with the Shimano stuff as well.


Well, there's this from http://www.sheldonbrown.com/harris/derailers-rear.html

"How Many Speeds?
Rear derailleurs often are referred to as "7-speed", "8-speed" or "9-speed." This is not as important a distinction as it might appear. Current model derailers are pretty much interchangeable within brands. A "7-speed" or "8-speed" designation generall just indicates that the derailer is an older design, or a cheaper model. They'll all work with all 3 systems, though the models marked "9-speed" will generally be slightly better (whatever cluster you use.)"

But Sheldon (or John) does say "pretty much interchangeable," so I suppose there
are some differences.

From the same page:

"NEW! SunXCD 8/9/10-Speed Rear Road Derailleur GS RD1105 $119.95 buy button

"The SunXCD Rear Road derailer can handle up to a 34t cog and is 8/9/10 speed compatible!

"Why do we think this is cool? Read on. . .

"Now you can run up to a 34t cassette cog with 7, 8, 9, or 10-speed STI levers.

" Up through 9-spd systems, Shimano Road and MTB shifters and derailers were interchangeable. So it was possible to use an MTB rear derailer and wide range cassette with STI shifters. All that changed with the introduction of 10 speed drive trains. With 10 speed Shimano, road is road, and MTB is MTB. They don't play nicely together. This derailer solves the 10-speed incompatibility issue. And being shiney silver rather than matte grey paint doesn't hurt one bit. . .

"SunXCD is a new company founded by the former president of Suntour Japan."

So I guess things have gotten more complicated recently.

- Frank Krygowski

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