Depends. Bike, car or motorcycle - I've stopped to help out lots of people. Some people - older people for example - can be much less prepared or equipped to deal with a mishap - particularly in winter.

But everyone broadcasts a level of approachability too and anyone that looks and dresses in an antisocial manner shouldn't expect lots of offers. Same for cyclists trying to portray an 'I'm a world champion' image. Have to say I've also driven by a few cyclists without stopping simply because of the lack of consideration they displayed earlier to other cyclists before they were 'grounded'.