Originally Posted by
ptle
I would go with a mix of both if possible. Only big difference between the two is the crank. Force has carbon BB30 cranks and are much lighter than Rival. However, the Rival cranks are supposedly really stiff.
FD are the same
RD, shifters, brakes are the same, but just lighter with a touch of carbon instead of aluminum in some parts.
I think g.r.e.g. is right that the shift lever is magnesium in force and alloy (a.k.a. aluminum) in rival. Don't think it really matters. What's a few grams in your shift levers...
I run rival. It's nice stuff. The rival crank is heavier, but it's a nice crank.