If I fit an expander ring and still run 2×10 will I die…or cause a mechanical disaster?
Theres some steep hills where were going in the Alps….

I wouldnt have thought so? Having a granny ring wont require any more chain length than is required with the expander..
Id imagine it would get to the point were churning the gear would be slower than getting off and walking though.

You should be fine as long as you don’t exceed the capacity of the rear mech. If you do exceed it, make sure you don’t use the big ring with the larger cogs.
Failure to do so can lead to a bent frame in some cases.
http://singletrackworld.com/forum/topic/my-first-bent-frame-and-top-customer-service-from-bikemonger-and-salsa#post-7120649

kerbdog – Member
Id imagine it would get to the point were churning the gear would be slower than getting off and walking though.

I realise that, but if I wanted to go for a walk, I`d take a dog not my bike 😉
I`d rather winch and be seated, than walk and push

How low do you really want to go?
32×42 comes in very close to 24/32