Gearing - Do I need a compact

[rowdysluggins]

So the DA cassette has a max jump of 13.3% (15->17)
Red 15.78% (19->21)
The 25 to 28 is not the biggest jump on either cassette 12% (25->28)

[5 8 5]

@rowdysluggins, not sure how you are calculating it but a 15-17 jump is a lot bigger than a 19-21.

[dunbar42]

On DA you loose the 16 going from 11x25 to 11x28, on SRAM you loose something, I guess you don't know what?

I don't think I'm "losing" anything. More like trading one cog for another. I just upgraded from 10sp to 11sp on my bike (both running 50/34 cranks):

12-27: 12-13-14-15-16-17-19-21-24-27 (10sp)
11-28: 11-12-13-14-15-16-17-19-22-25-28 (11sp)

The 3 tooth jump from 19-22 is noticeable when I'm climbing hard but I spend 80-90% of my time on the flats so it doesn't bother me as much as losing the 16T cog would. A Shimano 11sp 11-27 cassette would probably be ideal but they don't make one.

[eric]

The 19-22 gap is one reason why I use Shimano cassettes. I use the 19 and 21t a lot when climbing.

You can make an 11-27 out of a 12-27. You need an 11t cog and smaller diameter 11t lockring. Remove the 16t.

[rowdysluggins]

@rowdysluggins, not sure how you are calculating it but a 15-17 jump is a lot bigger than a 19-21.

Sorry, typo. It should have been 19-22 which is what the SRAM is. My bad.

[rowdysluggins]

I agree that if you rarely climb, the 16 would be a bigger loss. On the other hand, if you climb a lot, the 19 to 22 would probably be more annoying.
I climb a lot.

[boots2000]

You never mentioned what the effort level is when you are climbing the 7% ace climb at 70 rpm?
Do you ever want a gear that allows you to climb at an easier effort?
Many think climbing is hard because they have never done a climb at an effort that is not hard for them.
Find the gear that is low enough for your easiest effort.
Everyone is different in terms of preferred cadence.
I personally like a mid compact with an 11-28 cassette. I am light and I climb well enough where I could get away with 53/39 and 11-25. But with this combo I would not be able to go easy enough on some days at my preferred cadence.
I also like a compact 34-50 for some climbs but it is not my favorite, especially for racing. I find that I have to do too much back and forth shifting with a 34-50.

[ultimobici]

I used a 50/34 when I was still on 9 speed, mated to a 12-25. That was ok for longer Italian climbs averaging 10% with sections of 14%. But once home with flatter rides with shorter sharper stuff chucked in I found the 34 a hindrance. That was cured by having a 38.

As for the mythical 16 tooth sprocket, if you're running a compact it's irrelevant. It only matters with a 42 or 39.

[ultimobici]

Now that I have a 52/36 though I have no need to swap out the inner ring, just stick with an 11-27.

[bm0p700f]

Well if you can turn 39/23T on a 7% gradient stick with it. Can't stand compacts as the inner ring is practically unusable around here. I did a 932m climb early august in which the first 5km were at an average of 11% (long sections of 15%+ flatened out for a bit, then went vertical again peaking at 22% (argh the pain) on 41/27T. Power would have been woeful (~200W) as cadence was low (av 47rpm max 143 rpm). This climb was abnormal for me as it was in Italy, we don't have climbs like this in the U.K, a compact would have been useful here on the really steep 15%+ bits which brought down the average cadance alot.

I would go for the 52/36T combo over a fully compact as that would allow you to spin at 75rpm in 36/23T I think.

[ultimobici]

Thing is there is nothing in the south of England that warrants using a compact. Ditching, Box Hill and those in Essex etc are classic power climbs where hearing down simply slows you down. Climbs in the Peak District which are long as well as steep are a different matter.

[dunbar42]

As for the mythical 16 tooth sprocket, if you're running a compact it's irrelevant. It only matters with a 42 or 39.

It's completely relevant when you're on the big ring.

[ultimobici]

As for the mythical 16 tooth sprocket, if you're running a compact it's irrelevant. It only matters with a 42 or 39.

It's completely relevant when you're on the big ring.

Not if you're using a 50.

[jooo]

Finally one only needs to look at two 2 pro-cyclists that have vastly different approaches - contador and froome for instance, with similar outputs and results. Froome rarely out of saddle and higher cadence, contador pushing a bigger gear at a lower cadence (tends to run a large cassette to stay in the big ring longer), out of the saddle more often

I understand the comparison you're trying to make here, but think that you could have chosen better examples. Contador actually climbs at quite a high cadence compared to many riders.

A better example of someone who climbs at low cadence could be Horner, Scarponi or Ullrich etc.

From Team Sky camp saying Lower Cadence translates into more power for Wiggins:

http://www.telegraph.co.uk/sport/olympi ... trial.html

This isn't really related. It's mostly in reference to his time trialling. High RPM is an absolute necessity for 4000m on the track but a little less useful for 40km+ road TT's. Wiggins still seems to spin faster than most riders who've spent their whole careers on the road.

[dunbar42]

Not if you're using a 50.

Speak for yourself.

Oh, and on the Contador thing I read that he likes wide range cassettes because he can stay on the big ring on shallower hills saving him some front shifting. But unless you have a pro power to weight ratio I don't know how relevant citing pro setups is. At some point as you get more powerful you overcome the need to run lower gearing. I don't think most of us recreational cyclists have reached that point. Pros also have the luxury of running whatever crank/cassette combo they want to every day in a stage race which is a luxury most of us don't have.