The Shimano Ultegra 6700 cassettes feature a large selection of gears to optimize your everyday performance. The weight has dropped slightly by further drilling the rear cogs. In addition the individual teeth have been machined down to near perfection to improve shifting under load.
We also sell MTB cassettes. Just click the link to see what's available.
Nice and light but won't break the bank. You've got options, so do yourself a favor and pick the right cassette. Especially consider giving up your 11 tooth sprocket in favor of tighter spacing. I like the 12-27 with a compact crank. You get good climbing ratios and tight gear spacing for more efficiency. You spin a little bit higher at speeds approaching 30mph, but it's a trade-off that is well worth it for most.
I replaced an Ultegra 11-25 with this. Seamless, easy swap--runs great (though I'm still adjusting the derailleur).
Replaced the factory Tiagra cassette with this unit and have benifitted with lighter weight, way better shifting. All in all very pleased and would buy again in the future.
For 'cross I won't go any higher than Ultegra (most often only 105...) but the Ultegra 10s cassette in a 12-25 is perfect. Inexpensive, considering I have a number of sets of wheels, and fairly durable.
You must get the Di2. I had Sram before...never going back.