Re: Dual-Chain drive train

On 12/29/2024 9:39 AM, bp@www.zefox.net wrote:

Zen Cycle <funkmaster@hotmail.com> wrote:

https://www.bikeradar.com/news/buffalo-utility-s2
>
Made for developing countries to allow for easier transportation on
cargo bikes, without the exposure and complexity of an external
derailleur or hand-operated shifting (for an internally geared hub). It
was developed and patented with the help of SRAM.

 Are derailleurs really that bad? A whole new bike for the sake of a granny
gear seems slightly extreme. Internal pawls at small radius are going to
be more stressed  and harder to build than a rear sprocket of larger radius.
 I'll admit that the narrower flange of a multispeed rear hub impairs the
lateral strength of the rear wheel, but a hub with flanges spaced to leave
room for a two-cog stack would be vastly stronger. What is the "exposure"
alluded to above?
 Thanks for reading,
 bob prohaska

" Are derailleurs really that bad?"

Yes.
They last a long while for many competitive events (except criteriums where concrete abrades right through them). Derailleurs are the overwhelming choice for tourists, even of great distances, on roads whether paved or not. Derailleurs are also usually suitable to commuters although in salted areas that vulnerability is a factor.  Offroad is sorta sketchy in that failures are regular but alternates have some serious tradeoffs so the derailleurs just get bent back or replaced.
[note most offroad is recreation, by riders who can well afford replacement gear. Among the MTB riders, "I broke that too!" is not always a complaint, it's often a boast.]
Extreme use, where unsupported durability is critical, would lead one to a not-derailleur design of some type.
--
Andrew Muzi
am@yellowjersey.org
Open every day since 1 April, 1971