My current road bike has 4k miles overall, except for the chain which is around 3k (don't have exact mileage for the chain). My bottom bracket (BB30) has been experiencing some creaking noises, so I took it into a bike shop to have them look at it (I don't have bb tools). Since I knew that the chain was at the end of its lifespan, I asked them to change it.

They immediately told me that I should change my cassette (105) with every chain. I am no professional, but I know this statement is not true. Shouldn't a 105 cassette last 2-3 chains? Now if I screwed up the cassette with my poor gearing, that would not surprise me. So my first question would be is (without inspecting the bike) do you think I new cassette is needed so soon? I would believe the bike shop if they told me mine was worn, but the new-cassette-with-every-new-chain statement has my BS meter going.

Second question is regarding cassette size. My rear derailleur is a Shimano 105 RD-5600, which according to the specs supports up to a 27 cog. My current cassette is a 12-27. Bike shop doesn't have any 12-27s and even if I wanted to upgrade to Ultegra, a 12-27 doesn't exist in that groupset. My options are either 11-25 or 11-28. Would a 11-28 work? Would the jump for the 24 cog to the 28 be too big? I am a wuss and I like my 27 cog. Although I am a wuss, I love climbing, so most of the time, I am riding hills in my 25/27. I should be fine with a 25 cog for 98% of my riding, but sometimes I ride hills with steep inclines where I love my gearing. http://veloviewer.com/segments/2715220/ http://veloviewer.com/segments/689118/

Will I miss my 27 if I move up to a 25 or is the difference negligible? According to Sheldon Brown's gear calculator, the difference is 2.4 vs. 2.6. Is the shifting still decent on an Ultegra 11-28? I really don't need the 28. Or should I simply HTFU and get the 11-25?

If you made it this far, thanks for reading it all.