Originally Posted by AlexCyclistRoch

What my setup does is allow me to split nearly every gear, using the FD. For times like when the headwind gets just a bit stronger, I can go down a half-step, rather than 1 full gear. Extremely good for flat-land riding. Slight inclines that don't require a full step change, also. And, by 'extreme gears', I mean like a 53-11 combo; unless you are in the TdF, you rarely see anybody use this combo, so why carry them around if you don't need them? If you never need gearing above a certain lever (measured in gear-inches), you will be better off with a cassette that doesn't have them.

Originally Posted by Maelochs

Obvious solution would be to switch to a 48-tooth big ring. Obvious question is how can he develop sufficient power to climb but not to pedal on the flats?

Solution is important, question is not.

Originally Posted by bakes1

As has already been noted, not sure how you can be a strong climber yet not be able to pedal on the flats.
Something must be lost in translation and therein lies the answer.
And I am guessing the answer has nothing to do with gearing or cassettes

Originally Posted by chaadster

Well, I use a 53/11 just about every ride at some point, and there are a trio of climbs on my regular routes where I drop to the 36t, so maybe that's why I'm having a hard time imagining such a narrow range of conditions as you ride. Just this morning I ran the 53/11 up to speeds around 35mph; on the Down Oak Valley segment, it helped me bag a 10th place trophy: https://www.strava.com/activities/666650770

Anyway, I'm absolutely certain use of 53/11 is not a local anomaly, and if you were to look more carefully, you'd find a lot of fast riders using theirs.

Originally Posted by big chainring

Gear progression is easily modified. Experiment with different set ups. But the greatest variable is cadence. You can get going pretty fast in a 63 inch gear at 100 rpm. For many years the best time trialists used an 84 inch fixed gear(48×15). Ray Booty was the first to break 4 hrs for the 100 mile TT, and used an 84" fixed gear to do it. It's only with the advent of the 9,10,11 speed cassettes that cyclists seem to "need" the mega range of gears. The classic "10 speed"(5x2) can supply the same wide range of gears but the rider changes cadence more often to ease the "gaps".

For many years it was taught that high rpm's produced supple muscle and aerobic fitness. The new road bike craze and bikes being supplied with extremely large gears, 50×11 give me a break, has broken from the years and years of low gear-high rpm ideal of training. To each his own. But just today I was spinning effortlessly while others I was riding with were punishing themselves in high gear mashing.

Originally Posted by chaadster

Well, I use a 53/11 just about every ride at some point, and there are a trio of climbs on my regular routes where I drop to the 36t, so maybe that's why I'm having a hard time imagining such a narrow range of conditions as you ride. Just this morning I ran the 53/11 up to speeds around 35mph; on the Down Oak Valley segment, it helped me bag a 10th place trophy: https://www.strava.com/activities/666650770

Anyway, I'm absolutely certain use of 53/11 is not a local anomaly, and if you were to look more carefully, you'd find a lot of fast riders using theirs.

Originally Posted by redlude97

53x11 is only ~90rpm @35mph. Doesn't seem necessary at all. In fact if you look at the 2nd place on the list, they don't hit more than 120rpm and average ~105rpm which is the equivalent of only a 50x15 or 53x16. They never touch the end of their cassette whether it was a 11 or 12. I don't doubt that you like your 53x11, and it seems plenty of people do, but it really only became common in the last ~5 years. 53x12 has been plenty for most racers for decades

Originally Posted by chaadster

That's nice and theoretical, but real world factors like rolling and wind resistance make me certain kids are hitting the 11.

Originally Posted by 12strings

This is the first I've heard of people intentionally using small ring with their 11 cog....is this normal?

Some people must really hate shifting the front.

Originally Posted by redlude97

What? Unless your tire is slipping you can never go slower than the cadence in a chosen gear.

Originally Posted by bakes1

As has already been noted, not sure how you can be a strong climber yet not be able to pedal on the flats.
Something must be lost in translation and therein lies the answer.
And I am guessing the answer has nothing to do with gearing or cassettes

Originally Posted by smarkinson

2014 Giant Defy Advanced had 10 Speed 105 with a 50/34 chainset and 11-28 cassette (11,12,13,14,15,17,19,21,24,28)

The 50x15 gives a ratio of 3.33 and the 50x17 gives 2.94.

You can get a Tiagra 10 speed 12-28 cassette from here:
Shimano Tiagra HG500 10 Speed Road Cassette | Chain Reaction Cycles

which will give you that 50x16 with a 3.13 ratio.

This website gives you the full list of ratios for the 50x34 and 12-28:
HTML5 Gear Calculator

According the Giant website the Defy Advanced 2 for 2015 has 11 speed and disk brakes while the 2014 has 10 speed and rim brakes.

Now, if you have the 2015 and 11 speed 105 by some chance then things become trickier as there is no real easy way to get a 12-28 11 speed cassette. However, it does have the Shimano RS500, 34/50 crankset which will be easier to fit on a smaller big chainring as they are a standard 5 bolt design rather than the specific Shimano 4 bolt design.

A 48T big ring by 15 at the back will give a ratio of 3.20. Thing is, 48T 110BCD chainrings are not common. In fact they are bloody rare. I don't think Shimano actually makes one but I could be mistaken on that.

A 46T big ring would be no help to you as the 46x15 is 3.07 and then 46x14 is 3.29 which are both close enough to the 50x17 (2.94) and 50x15 (3.33) as to make no difference.

If you do have an 11 speed bike I'd be tempted to get a 12-25 cassette and take the bottom half and stick it onto your 11-28 cassette. That would give you the golden 50x16 but it does mean needing to buy two cassettes.

I hope for your sake you have 10 speed as the Tiagra 12-28 10 speed would be the cheapest option.

EDIT: It appears the Tiagra 10 speed does not have a 16T. So you would probably be better off with the 105 12-27 or taking the 105 12-27 and mixing it with your existing 11-28 if you need the 28T.

Originally Posted by dartanyan

Climbing comes effortless to me due to my weight and aerobic fitness. you have to agree 2 riders one with 165 lbs other with 220 lbs with same fitness level. 165 lbs will climb lot better. but there is no way he is going to be pedaling as hard as a 220 lbs rider on flats.

Originally Posted by dartanyan

Thanks for the indepth response. Yes it is a 2015 defy adv2 with 11 speed shimano 105s.