Originally Posted by stephtu

As stated, compact is going in the wrong direction if you want lower gears. 34 tooth instead of 30 (presumably) tooth smallest ring. To get lower gearing, you can get either a cassette with larger cogs, or a smaller granny ring, or both. You would likely need a new rear derailleur to handle larger max cog + more wrap (mountain bike *9-speed*, even though your bike is 10-speed, because Shimano's MTB 10-speed derailleurs use a different amount of cable pull than is compatible with road STI), and a new chain. For parts cost, shopping online, about $25 for a chain, $45-$65 for a rear derailleur, $30-$60 for a cassette.