Originally Posted by
PhotoJoe
My bike showed up with 11-25. As the first C/A GMR ride approached, I realized I would never make it in my current condition. I swapped it out so I had 50/34 with 12-28. There are still times I wish I had lower, but I've sucked it up and survived. It's never stopped me, but do wish I could spin more on some hills.
Depending on which RD you have, Ultegra and Tiagra come in a 12-30. I put this on my bikes. One has a Dura-Ace RD-7900-SS, which only comes in one cage length. The shop that did my BG Fit took out two links, so I can't go big-big anymore. Before he took out those links I could, (not that I want to, but some times I forget what gear I'm in and accidentally shift into big-big). Next time I remove my chain to clean it, I'm putting those two links back in. The other bike has an Ultegra RD-6700-SS (mid-cage length). No problems at all with that bike. Both bikes are 50/34 in front. (Another bike has a RD-6700-GS, (long cage), which is the triple dérailleur, so wouldn't expect it not to work on a compact.)
The Mike Sherman Gear Calculator shows a 34-28 as being 32.3 gear inches and the 34-30 being 30.2 gear inches. That's a an extra 7%! Most useful for us heavier, out-of-shape folk when the grades ramp up steeper.
Some time later this year, I'm switching one of the bikes to that new Ultegra 6800 group, which is available with a 11-32 cassette. Using the 50/34, that would give me a lowest gear of 28.3 inches. Not quite as low as a triple with a 12-30, but low enough that the Baldy ski lifts are possible. There are large gaps, but I can live with them.