Originally Posted by tblendell
still trying to make it up the hills with my poprad.
can i use a mtn. bike cassette with my shimano 105 rear der.?
i already switched out the cranks with a truvativ double in the front so i'd rather not switch to a triple in the front.
there 2 limitations to consider: derailleur capacity and max cog size.
the largest rated sprocket for the 105 is 27 teeth.
capacity is 29 teeth, based on how much extra chain the derailleur can accomodate. subtract max/min chainring difference and max/min rear cog difference and add these numbers together.
it is said these limits are conservative, but you'd have to be aware you might run into problems ( in this case the derailleur hitting the cogs. without the specifics of your set-up , i can't comment on the capacity.
if you have a compact front crank you could run something like a 46/34 front and 12-27 rear
a 34 x 27 combo is about equivalent to a 39 x 32 set-up