On Thu, 30 Jul 2020 11:49:52 -0400, Frank Krygowski wrote:

On 7/30/2020 11:35 AM, AMuzi wrote:

The most common failure being "merge with spokes".

I've seen such things in real life. On two different occasions, I fixed
similar problems for other riders so they could finish their rides, with
perhaps fewer gears than they had at the start.

But that sort of failure can happen anywhere if the derailleur is
adjusted badly enough. It doesn't have anything to do with gravel
riding.

I wondered if Russel's derailleur tried to swallow a rock.

Or a stick. Very common here on bush tracks. Gum trees shed leaves and
branches copiously when heat stressed and you have to be carefull you
don't flick a bit into the spokes, etc.