Hello,

Recently I learned the reason I struggle climbing hills is because my road bike is equipped with Shimano HG50 9 sp. 11-25T casette. The Rear Derailleur is Shimano Tiagra 4500 9 speed.

I was told upgrading to a more teeth casette would help alot. Researching I came across Shimano CS-4600 Tigara 10speed 12-30T at rei.com for $50. Are these casettes interchangable? Do i need a new chain? My existing chain is Shimano HG53 9 sp.

Thanks in advance for answering these questions for me!!

NOt sure if this information is irrelevant or required but the current Front Derailleur is Shimano Tiagra 4500 and the cracnkset is Shimano Tiagra Compact 34x50T.