Anyone aware of a product which protects the rear derailleur during transport? I'm thinking of a plastic box which clips on to the chain stay and protects the derailleur for when I've got three frames piled on top of each other in the back of the car. I've seen the M-Wave etc. which seem to be for jessies who don't like grime on their boot linings, but I had something more resilient in mind.
If it doesn't exist yet it was my idea first!
I just use an old bath towel.
Don't think so - most people remove it from the hanger and bubble wrap, I'd think.
[img] 
[/img]
I have used a proper thick cardboard tube with a slot cut out before, worked for me. I cut an extra slot out to hook it round the seat stay so it didn't really move either.
Get one of these, or similar from ebay:
PaulD
Wrap a bit of bubble round the chain stay
unbolt the mech (leave it on the chain)
tape/zip tie it to the stay
wrap in bubble again
^^ That's what I said 🙂
what maccruiskeen said
[edit]and what dezb said before him[/edit]
All good suggestions, but not quite what I'm after. The main risk is handlebar (bike A) <> derailleur (bike B) interaction going over speed bumps / potholes in country lanes / unpaved roads. Towels guard against muck, and sticky-outy bits might deflect a branch or something coming from in front, but...
Maybe I should take a file to one of those snap lock tupperware things and see what I can manage, then skip on down to the patent office.
How about a large sponge from Halfords, cut into it from the side, might need a bit of hacking into it, then slip it over the derailleur and pop a ziptie round it. Might need to ziptie the chain to the derailleur so it slips into the sponge. Someone told me about this method, but I have never needed to use it, but it sounds as though it could work.
Ooh, a sponge... Hadn't thought of that. My old man used to have loads of this weird high density foam stuff (looked like it was made up of lots of smaller bits stuck together, hence its affection moniker of 'dog meat') which you could carve into whatever shape you needed. Two halves clamped around the derailleur and bungied together might do the trick. May not guard against bending though - possibly a sophisticated version of the bath towel.
Sponge INSIDE the snap lock tupperware though = pathway to safe transport and, when taken to its logical level of mass production, untold wealth and happiness!
(I'm completely aware this is a clear case of over-engineering for a non-existent issue, by the way.)