long cage rear der on double
is there any harm in running a long cage rear der on a cross bike with a double ring up front? Or is it just unecessary? I bought one by mistake and raced with it last Sun. I run a double 39/46 up front and 12-25 in the back. I noticed when I am in the small ring and shift to a small cog, the chain skips when I really crank hard. Is this due to the long cage or do I need a new cassette or chain (chain is new, cassette shows no wear)? I don't think the long cage keeps as much tension on the chain as a short cage. However, the shift from the 39 to the 46 is sweet! Comments, suggestions?