SoSmellyAir

If I understand correctly, this is because 11 speed freehubs do not totally fit all 11 cogs. The outermost / smallest cog is a special cog which sits halfway on the freehub and is held on by the lock ring. Shimano only makes this special cog in 11T, 12T, and 14T. Since most people seem to prefer a bigger range, 11-xx cassettes are the most common ones.

SoSmellyAir

Is there really that much difference in efficiency, wear, and looks between, for example, 52/36, 50/34, and 48/32 chain rings?

WhyFi

There's enough efficiency difference that TT specialists go big.

Kimmo 

Sorry, I meant 11 tooth cogs are mandatory in current stuff, not 11 speed is mandatory.

The 11t notch on HG splines has been a thing since since the 8s era, IIRC, NBD.

gsa103

The reason the TT specialists go big has nothing to do with the front gear efficiency. They go big because of the REAR gear efficiency. Small gears below about a 15T are less efficient, especially with an imperfect chain line.
They still ride "normal" gearing during non-TT stages.

Big wattage TT specialists want the big gear so that they can spend the majority of the race in a 60/15 combination, rather than 53/13. This isn't an issue for mere mortals.

WhyFi

Yup, I'm aware.

Kimmo 

I figure another reason TT goes big is because it makes the ratios closer. Sure can't hurt.

Seattle Forrest

That's why I went to a 12-28. I'm surprised that I actually do miss the 11T occasionally, but not enough for it to be an issue.

SoSmellyAir

Are you on an 11 speed Dura-Ace 12-28 cassette? If so, any issues with creaking from the big spider or wear on the larger titanium cogs?

Ataylor

Okay, I see what you're saying. I mean I have yet to try anything outside of an 11/32 (from what I can remember, anyway), but if shifting is less disruptive (and obviously so) than my old cassette (which was very obviously disruptive), then honestly, it'll be totally worth it for me to have spent some time figuring this all out. Thanks, of course, to everyone's help.

Will do. Thanks for linking me.

No, I'm not saying that you can't tell the difference between the 11th and the 32nd cog - how could you possibly not tell a difference? What I wasn't certain about was how noticeable the shifting was between cogs that had 1 space between them (e.g. the 17th and 19th cog) and those which had more (e.g. 30th and 34th, which has 3 spaces).

Wow, that's interesting that that specific cog is so highly desired. I was actually wondering about that the other day. The 16, 18, 20 and 22 cogs are missing from my 11/28, that were all a part of the 11/32 cassette that I've been using (and have been use to) for the past several years now. I guess only time will tell how big a difference it'll be and if it'll even matter.

Yea', that's exactly what I plan to do. I had a chance these past couple days to do just that, but was overwhelmed with personal obligations. Hopefully soon.

guachi

That SRAM ratio looks really good. If you could make it 12-spd and add a 32 it'd be even better. I have Shimano's 11-spd 11-34 and the ratios are stupid. There are no one tooth jumps.

vane171

Didn't read the whole thread but to get a good idea what close gears mean is this - try not using the second and fourth gear in a vehicle that has manual shifting with five gears.

SoSmellyAir

There is nothing magical about the 16T cog, and its presence in a 11-32 cassette does not somehow make this cassette per se better than a 11-28 cassette. Recall what I said above about a single tooth jump between cogs making a bigger difference toward the small end of the cassette. Many people, myself included, prefer to have single tooth jumps all the way up to at least the 17T cog. So, when they (and I) use a Shimano 11-28 cassette it feels like a 16T cog is "missing." As in, I would be riding along on the 17T cog, pedaling faster to accelerate, and then spinning past my optimal cadence, so shift onto the 15T cog, but this drops my cadence too much, so I am making less power and therefore unable to maintain that speed, and so I have to shift back onto the 17T cog. (Recall I also said above that I am fairly weak and have a narrow powerband.)

A 11-32 cassette is even more "disruptive" than the 11-28 cassette because it has single tooth jumps only between the smallest four cogs: 11T, 12T, 13T, 14T. Then there are two teeth jumps to the 16T, 18T, 20T, 22T. My bike (like many sold in the last few years) came with a 11-32 cassette and it has never felt right at decent speeds. That is what prompted me to look into and learn about gearing.

If you are really 98% on the flats, you won't regret having a closer ratio cassette that 98% of the time.

SoSmellyAir

Yes, bigger range is not better if you don't need the range.

Ataylor

Thanks for your help and for explaining. I've never calculated my cadence. I've thought about it before, but never followed through. Are there any reliable sources you can recommend in terms of learning about gearing? I've really enjoyed watching a lot those GCN videos (I think it's safe to assume they know what they're talking about for the most part?), so I'll see if I can find something on their channel as well.

By the way, you're on a 12/28 DA cassette, right? Can that be used with a full Di2 Ultegra setup? I have a feeling the whole 16th cog thing won't be an issue for me, but I've been taking notes just in case.

SoSmellyAir

I have never measured my cadence. I just rode the same route over and over again while tracking which cog I was on, and the points on that route where I found myself shifting back and forth between two cogs with neither feeling just right, at which point, if I had lost track, I stopped to look at which cog the chain was on. I looked into getting a cadence sensor at one point but the reviews were quite mixed about their accuracy.

It is just math, so I don't have a source. This gear calculator helps visualize gearing by calculating velocity from cadence for each gear ratio.

Bicycle Gear Calculator (gear-calculator.com)

No. I looked into but decided against one, as explained here. Bike Forums - View Single Post - Custom 11-Speed Ultegra 12-28 Cassette? So I am using an Ultegra 12-25 cassette. If I understand correctly, all Shimano 11 speed drive train components from the current generation and the immediately prior generation are cross-compatible. For example, I am using a current generation Ultegra CS-R8000 cassette with a last generation 105 RD-5800 rear derailleur equipped with the last generation Ultegra RD-6800 jockey wheels.

Kimmo 

As for your cadence, I'm tipping that if you work on a nice smooth spin, and getting it nice and fast, you'll end up most comfortable somewhere around 90rpm.

That's about where the sweet spot is between pushing too much resistance and working your cardio too hard.

vane171

Not sure anyone commented on the thread title question - Closely-spaced ratios = quicker shift?
Yes, you get quicker, smoother shift if the sprockets on the cassette are one or two tooth difference. Usually you notice the longer time it takes for the shift to the biggest sprocket which most people have extra large by several cogs (like in your case the 32 one) relative to the one before it, also you notice it more if you have the old friction shifting on DT. It takes a little bit for the chain to get lifted on that much bigger sprocket, similar to front shifting which is not as easy or smooth due to big difference in chainrings.

For the second part, no it doesn't make sense to have 32 sprocket on your cassette, that is a huge gear even if you ride in a moderate hilly place. Basically if you don't ever use it, consider getting another cassette, benefit will be that your gears will have smaller steps gear to gear as you shift.

I am the opposite of what you have, I happen to still ride an older bike with the 52/40 and 13/23 cassette in a moderate hilly place with some bigger hills. The cassette is actually 8 speed 13/26 but I can't shift to the largest sprocket because then the RD would start rubbing against wheel spokes and that is asking for a trouble. SO effectively my 8 speed cassette is 7 speed and on the bigger hills, I sometimes ride a bit and then walk the rest.

woodcraft

So you get to a steep hill, slow 30 rpm cadence, get off & walk the rest, but at least the shifts were quick for the first 40 feet!

jaxgtr

Which is why I pulled that cassette off my Domane and have it sitting in a box. If I go to the mountains or hills, I will run it, but outside of that, will never use it.

Ataylor

Sorry, maybe I'm misunderstanding you (or not fully understanding what cadence is all about), but cadence means the amount of times you rotate the crank per minute, right? If so, would you mind explaining what exactly tracking which cog your chain is in has to do that? I honestly don't get it.
Alrighty, thanks.
Oh, my mistake. I totally misread your earlier post. Thanks for clarifying.

And not that it matters, since it's not compatible, but that single post of yours (if it held true for a high majority of DA owners) had enough information contained within it to give me reservation about going the DA route. The potential creaking, the less-durable metal, which makes it more prone to faster wear and cracking and what not. Outside of professional cyclists that are counting every gram, I don't understand why anyone would choose DA over Ultegra.
Yea', they did, but thanks anyway for your reply. A quick update, though: I've since decided to go with an 11/28 cassette, but not before test riding my current cassette to see which cogs I spend the most time on. An 11/25 crossed my mind for a second, but again, I need to ride my usual path and figure out my riding habits before I make up my mind.

jaxgtr

the 105 or Ultegra cassettes are a much better bang for the buck if you are running Shimano. DA is nice, but stupid expensive when you are not being given the things by a company rep for your team.

SoSmellyAir

Yes, cadence is crank revolutions per minute ("rpm"), same as what a tachometer measures in a car.

Different motors have different power bands. For example, Audi / VW 2.0T FSI motors can generate peak torque between 2K and 5K rpm, and thus have a relatively wide power band. Whereas Honda 2.x VTEC motors only generate peak torque from 5K to 7K rpm, and thus have a relatively narrow power band. Power is torque multiplied by RPM. Both motors generate power; the Audi / VW at lower rpm, the Honda at higher RPM. The peak power of both motors maybe similar, but the Audi / VW is easier to drive fast because its peak torque is reached sooner and has a broader powerband. The Honda motor needs to be spun up to a much higher RPM before it is generating power at its peak torque.

Cyclists are motors too but their powerband is much narrower. Otherwise we would not need gears, or we could make do with just six like a car.

Cadence x gear ratio x tire circumference = velocity. Using my previous example where I was accelerating and have reached the upper limit of my powerband, so I am spinning a bit too fast and need to shift to the next highest gear. At the instant I shift, the gear ratio changes nearly instantaneously -- at least if the derailleur is setup well -- but not my speed. So at that instant the motor (i.e., me) is forced to pedal at a lower cadence. If that lower cadence is outside my power band, I lose power, and cannot maintain my speed, and maybe forced to shift back. But if the next higher gear was not so high, maybe I could have stayed within my power band and accelerated to and maintain a higher speed, at least until the terrain changes again. How do I know if I am right? By looking at which cog I was on, and whether there is a cassette with a smaller gap to the next highest cog.

SoSmellyAir

I would have bought a DA 12-28 cassette but so many online reviews raised issues regarding its durability.

SoSmellyAir

The Dura-Ace 12-28 cassette is compatible with other Shimano 11 speed drivetrains (at least the current generation and the immediately prior generation); just not so durable.