Originally Posted by
gster
Re: My Failed Derailleur Project
I now know why 10 speeds have those big plastic discs on the rear wheel
and why sometimes they have a big chunk missing.
It's to stop the derailleur from smashing into the spokes...
I'd set the derailleur up with the SA throttle shifter.
Like a regular trigger it has a stop (indexed) and I thought
that the amount of travel would work the derailleur.
It didn't...
The shifter continued past the first stop pushing the derailleur
too far into the spokes.
I may re visit or wait for a proper vintage 2 cog derailleur
to show up.
I'm getting a little confused - it happens more these days. First, by "10 speed" you probably mean a vintage friction-shifted 2x5, not a modern indexed 2x10 or 3x10?
In modern bikes I don't think I've ever seen the big plastic (or metal) disks between the cassette and the spokes. We are supposed to adjust the derailleur travel limit screws to make sure the chain does not get driven into the spokes, and in my past 35 years I have not known them to fail, starting with my 2x6 1984 Trek 610. It was also the case 15 years earlier with my first 2x10 Falcon with a Campy Gran Sport. Back then we routinely had the LBS remove those (hence not looking like the dorks we were!), but I still didn't have any chain control faults.
You said (I think!) that you tried to depend on cable/shifter adjustments rather than derailleur travel limit screw setting. In this case a dork disk might help, but it's better just to set your screws correctly and check the derailleur for bending or flexing rather frequently. Or get a frame and derailleur that is higher quality, less flexible.
BTW, I'm not sure that claw is positioning that derailleur where it can shift your new sprockets correctly - it looks like the mech is pretty far behind the rear axle, and I expect that the free length of chain is too long for good shifting without a lot of overshift.