Wow, great info, How do you know by my original post that I have the SS RDR? Another question, Is a 12-27 enough of a difference in the mountains to even bother with the change?

My local bike shop told me he would put on a 11-32 with a MTB RD if I wanted... he said he does it all the time. Is this a safe thing to do and want cause any long term problems with my bike, especially considering I will be doing the majority of my riding in the flats.

If you are doing long mountionous rides, it will be worthwhile to change to a compact crankset first. This will give you a 15% change in gain ratio. Changing from a 11-25 to 11-28 will add another 12% for a 30% change in gain ratio.

Both of these changes can be done without changing deraillaurs. You could put a MTB RD on with a 11-32, but spacing between the gears gets to be an issue.

The combination of a compact crank and an 11-28 will get you up 99.99% of all the hills you will ever come across.

This is a great tool for evaluating changes in gearing: http://www.sheldonbrown.com/gears/

To add a question (thanks op):

I have a standard Ultegra 6600 double (53/39) and (11/23). Due to a summer mountain ride I need some lower gears. Would I be able to add any significant gearing improvement by just swapping to IRD 11-30 cassette? Or should I go to a 32 or 34 and get a different rear derailleur?

I could also go to a compact crankset, but my budget is probably <$150 total so doing crank, cassette, chain, might be out of question. Thanks!

I've got a 12-28 SRAM Red cassette that I swap around from bike to bike when I have a really mountainous group ride or race. All my cranks are standard 53-39. The big cassette works well with Ultegra (6600), DA (7800) and SRAM Red and Force rear derailleurs. None of these RDs have long cages. Some of my buddies laugh at my giant cassette until they watch me disappear into the distance on long, killer climbs. Before flaming me for the previous sentence, I know I am too slow and fat for this sport, that I am an awful cyclist and the only reason I can drop my mates on climbs is that they are the only cyclists on the planet worse than I.

I didn't list that option, but it's the first one I was going to try as I have a Rival 12-28 cassette. Thanks. I may still need to add some more gears though, being old, fat, and out of shape.

If your going to use a standard crank, get the MTB RD & a 11-32 or larger cassette. A standard crank + a 11-32 = a compact crank + a 11-28 for climbing ability.

http://i289.photobucket.com/albums/l...tvStandard.png

Thanks -- that is helpful to see. I must admit, that graph suddenly made a lite go off in terms of gearing. So, thank you very much.

i ride with 11-28 on my ultegra SL group. compact in front of course.

Barrettscv,

Are you using a compact 50/34 with the 11-32 Apex? Are you using the Ultegra compact derailleur as wee?

Andy

Dyna-Sys 10sp derailleur
 

This thread got me thinking and I wonder if this will work?
Shimano SLX Dyna-Sys RD-M663 Shadow Rear Derailleur - 10-Speed with Utegra or Dura-ace sti shifters and either 11-32 Apex cassette or Sram-XX 11-32 cassette?

The 10-speed mountain rear derailleurs use a different actuation ratio, so they won't index correctly with road 10-speed shifters. But you could use a 9-speed mountain RD... I'd suggest a non-Shadow like the RD-M771. Or if you like upshifting more than one cog at a time, you could use a RapidRise variant like an RD-M770... I've seen that setup before.

Here is another useful graph to help visualize the difference in gear ratios
I would also recommend considering a compact 50/34 chain ring set for climbing:thumb:

http://phys.csuchico.edu/~eayars/images/gearing.png

I am using the compact crankset with the 11-32. However, I am using an Ultegra "GS" derailleur. The "6603" GS type has a longer arm for additional chain slack take-up.