Road/MTB derailleur spring differences?

FWIW, my Dura Ace and Acera springs look the same...

Squid-in-Training said:

MTB derailleurs have coil springs that move along the axis of the coil
windings. Road derailleurs have springs that rotate perpendicular to the
axis of the windings. Why?

Not all road ders use torsion springs for the lateral linkage; some
(in fact, most if not all of the ones I've examined) use a coil, just
like a typical mtb. Typical road and mtb ders use torsion and tension
springs in the same places in my experience.

Quoted message said:

MTB derailleurs tend to get crud in the pivots, and/or the springs tend to
"get soft." Why not use road-style springs in the MTB derailleurs?

My guess: Dirt. I would expect that a coil spring and simple pivot
linkage that's resonably resistant to getting gunked up with crud is
easier and cheaper to make than a dirt-resistant joint containing a
torsion spring.

--
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Werehatrack said:

Squid-in-Training said:

MTB derailleurs have coil springs that move along the axis of the
coil windings. Road derailleurs have springs that rotate
perpendicular to the axis of the windings. Why?

Not all road ders use torsion springs for the lateral linkage; some
(in fact, most if not all of the ones I've examined) use a coil, just
like a typical mtb. Typical road and mtb ders use torsion and tension
springs in the same places in my experience.

Quoted message said:

MTB derailleurs tend to get crud in the pivots, and/or the springs
tend to "get soft." Why not use road-style springs in the MTB
derailleurs?

My guess: Dirt. I would expect that a coil spring and simple pivot
linkage that's resonably resistant to getting gunked up with crud is
easier and cheaper to make than a dirt-resistant joint containing a
torsion spring.

You know how much coil springs suck. They cause derailleur failure way
early and I'd rather flush the spring and get it working rather than having
just a plain weak coilspring that can't overcome the slightest amount of
cable friction.
--
Phil, Squid-in-Training