change from 39/53 11x25 to 39/53 11x28?
Hi I'm currently riding the Giant TCR Advanced SL4.
I currently run a 39/53 double crankset with a 11x25 rear cassette.
I need more options while climbing steep gradients, but don't want to lose speed on the flats and downhills.
I was thinking about changing the rear cassette to 11x28 and keeping the crank as the 39/53.
Would this work and would I need to change any other components?
Thanks in advance.
Top 100 Contributor
You'll need to make sure your rear derailleur can take sprockets up to 28 teeth.
Do you have a 105 / ultegra / dura-ace rear mech?
With 105, only the RD-5700 is ok for 28 or RD-5700-A for up to 30
With ultegra, only the RD-6700 is ok for 28 or RD-6700-A for up to 30
With Dura-ace, only RD-7900 is fine for 28.
I personally swap between 25 and 27 on my ultegra/dura-ace ones with 39x53 at the front, but never tried 28.
However, you'll find plenty of reports that 28 is fine with any short cage rear mechs (except the dura-ace RD-7700 which goes only to 26), and I know of some who run it successfully. It's probably at the very limit of what the RD can do, though, so not to use too much in that configuration.
The one thing you'll need to be more careful about though is your chain length as it may be too short for the extra sprocket size.
After you checked this, just be careful when shifting to not be "big-big" or "small-small" and you should be fine.