Originally Posted by
avion2001
What is the largest cassette I can get for my Shimano Ultegra groupo... I may not be asking my question correctly (newbie alert). I am going riding in the mountains this summer and am concerned about not having a low enough gear. Any help or advice for mountain riding would be useful!! Right now I have a 12-25 but would like something a little bigger like a 11-28 or even 11-32 if either of those even exist. My bike is an Orbea Orca that is less than a year old.
For a cost-effective upgrade, one option is this kit: a 10-speed 11-32 cassette, a 9-speed Shimano XT RD-M771 rear derailleur in either mid-cage or long-cage, and a new 10-speed chain.
Another option, like some folks already said, is an 11-28 cassette and a compact crankset. You might be able to eBay your full-size crankset to offset the cost, and you'd be able to keep your Ultegra derailleurs.
The strong points of the first plan include a higher high gear, and a smaller change in cadence when changing from one chainring to the other. Big gears with lots of teeth also take longer to wear out
The weak points include extra weight, bigger cadence jumps from cog to cog on the cassette, and an obvious un-roadie aesthetic.
The strong points of the second plan include a similar low gear with less weight and a more road-bike appearance, as well as smaller jumps in cadence when shifting across the cassette. The weak points include having to front the money for an expensive new crankset, the bigger jump in cadence between chainrings, and in my experience, a bit greater chance for chain drop.
Personally, I switched my rain/commuter road bike from a 12-26 with a 53-39, to an 11-28 with a 50-34, and I regret it now. When I change that bike from 9sp to 10sp, it's going back to un-compact in the process.