I purchased a Shimano Ultegra 11-28 CS-6700 speed cassette (cluster) in March 2010 from Bike24.net for a landed cost of AU$61.00. This review reflects my usage of the Ultegra 11-28 CS-6700 speed cassette over a four month period, aka the BackpackGearTest.org approach. The cassette has been fitted to my Look 555.
Shimano describe the CS-6700 cassette sprocket thus â€¦
A more rigid aluminium carrier keeps the HyperGlide cogs in check when shifting under load and each shift is lightning quick thanks to revised tooth profiles. New gear ratio options add combinations which work particularly well in combination with compact gearing.
Shimano also state that the CS-6700 11-28T requires the use of RD-6700 or RD-7900, however I have my 11-28 cassette fitted to my Look 555 which has a RD-6600 Ultegra SL rear derailleur.
Shimano have published two related technical documents: Technical service instructions covering installation of HG sprockets and the Ultegra CS-6700 spare parts list. Please click on the links to download the documents.
FIELD TESTING (Two months on the bike)
Despite Shimano’s comments otherwise I have found the CS-6700 11-28 cassette works fine with my RD-6600 rear derailleur. That said I wouldn’t go as far as Shimano has and describe each shift as lightening quick. In all honestly I cannot notice any difference in shifting from the OEM cluster that came with the bike, a CS-6600 11-23 Ultegra SL. Both clusters shift well for me, I cannot discern any speed differential and really cannot notice any difference from the clusters fitted to my other bikes.
The above notwithstanding I am happy with the way the it shifts and shifts under load. As long as I have it dialled in okay the cluster shifts well. I wouldn’t describe it as having any issues.
So at the two month mark I had had no issues with the cluster, it does what it should do and appears to be wearing okay.
LONG TERM TESTING (Four months on the bike)
I am a bit late with the the long term testing update with this review being as it is now September 2010, i.e., five months after fitting the cluster. The cluster has now done 2,594 km at the time of writing this update.
At the time I fitted the cluster, the chain on the bike had done 3,902 km. Okay so not a new chain/cluster update, but I did want the extra gearing option for some hills rides at the time so went with the new cluster/old chain combo. I haven’t seen any evidence of excessive wear or other reason to be concerned with this decision as yet.
As per the field testing update the cluster continues to perform as expected in terms of shifting. However, from the point of view as to why I purchased the 11-28 cluster; to help with the hills climbing, I would say I am disappointed with the level of performance increase. To put my comment into context the Look 555 is fitted with standard 39/53T chain rings. I really cannot notice any significant improvement over climbing with the 23T cassette compared to the 28T cassette; there is some for sure but not as much as I hoped for. Maybe I was being unrealistic. Anyway with hindsight I suspect a more ideal upgrade would be going to a compact double chain ring combined with the 11-28 cassette.
All that said, I suspect I will stick with Shimano CS-6700 11-28 cassettes for the foreseeable future on both the Look 555 and in due course on the Giant CRX 1 assuming the wear levels are acceptable.