meb <
[email protected]> wrote:
> I?m seeing one set of specs listing the no brake version being 42 grams lighter than the roller
> brake version with the coaster brake intermediate. Manufactures? web site shows 179 g difference
> for the 2003 roller brake vs. no-brake S7?s. I would expect the brake to weigh a lot more than 1 ½
> ounces unless it?s a lot simpler than other drum style brakes. The analogous P5 units are
> different in weight by 206 g. Are you inferring the hub on the S7 roller brake version is made of
> aluminum or other lightweight metals?
"Roller brake" is Shimano's trade name for their cam-actuated drum brake. The SRAM hub has a
conventional drum brake with one shoe leading and one trailing.
Every version of the SRAM or Sachs drum braked 7-speed hub I have seen uses an aluminum shell. Every
version I have seen without a brake uses a steel shell. As a result they weigh almost the same.
> Anybody know if that roller brake itself is heavy or light, and if differing materials are used
> between the models ?
The drum brake on the S7 hub, being of normal design, has a steel liner pressed into a cavity in the
hub's left flange. The removable portion is a steel cover plate with the brake shoes, reaction arm,
and actuator arm built in. It is fairly heavily built, but it is also more integrated into the hub
shell than Shimano's spline-attached brake and thus not nearly as convenient to omit.
> BTW: Does anybody have any knowledge of the drive efficiency of the three S7 brake configurations
> to each other and also relative derailleur systems.
I have seen results of some fairly iffy testing on this topic, but I don't know where to find them
posted. The drum-braked and unbraked models are identical in efficiency, with the coaster perhaps a
little behind them due to brake drag (but not due to gearbox differences). All of them, in my
experience, are less draggy than the Shimano Nexus 7 hub with or without a brake.
Chalo Colina