I shortened my chain, is this bad?
&quot;Never run with a chain that is too short, except in an emergency.&quot; (from Sheldon Brown's Derailleur Adjustment page). If a short chain ends up on the big chainring and big sprocket at the same time, then the derailleur will probably get damaged.
To avoid damage, there should be at least one full link of overlap when the chain is put around the big chainring and big sprocket (with the rear derailleur bypassed).
Unless the chain was too long to begin with (which is unlikely), you should get a new chain.
You can also by a single link instead of getting a whole new chain, and if you get a replacement master link, it will be easier to disassemble your chain for cleaning in the future.