Ataylor

Couple questions for you guys. First, what exactly are the benefits (if any) of having closely-spaced ratios? I've heard that there's a wider space in between the cogs for something like the 11/34T than there is with the 11/25T or 28T, correct? If so, does that translate to a noticeably quicker (or perhaps "snappier") shift?

The other thing is, I've heard people mention that you should stay away from gears that you don't need. I ride on flats like 98% of the time, so does it make "sense" for me to have a 50/34 crank with an 11/32 cassette? Or is there a "better" configuration? I mean I know this is super subjective, but I wonder if anyone could at least guide me in the right direction. Perhaps a 28T is better suited for someone mainly on flats? Or is there more to it than that?

HTupolev

The main benefit of having closely-spaced ratios is that you have closely-spaced ratios.

Power is, more or less, your pedaling torque multiplied by your cadence. Shifting allows you to balance how much torque your legs are having to put out versus how fast you're having to spin your legs in circles. Having more closely-spaced ratios means that you have finer control over this.


Not really. Theoretically there's probably a small difference, but it doesn't really show up in practice.

Wider ratios primarily make for a more disruptive shift, i.e. they'll create a larger change in the pedaling force you're having to push with, and the rate at which your legs are spinning.

Quote:

The other thing is, I've heard people mention that you should stay away from gears that you don't need. I ride on flats like 98% of the time, so does it make "sense" for me to have a 50/34 crank with an 11/32 cassette? Or is there a "better" configuration? I mean I know this is super subjective, but I wonder if anyone could at least guide me in the right direction. Perhaps a 28T is better suited for someone mainly on flats? Or is there more to it than that?

This really depends on the particulars, because it depends on the terrain and the rider and the riding, and variation in all these things is huge. What's the context? Do you have a bicycle and you have some issue with it? Are you contemplating a bicycle purchase, and you're wondering what to look for? How strong of a rider are you, and what sorts of rides are you doing?
What parts of your gearing range are you spending a lot of time in?

WhyFi

HTupolev explains it really well, but I'll elaborate a little based on my experience.

Personally, I didn't really care too much about close ratios until I started training and riding in fast-paced group rides. In situations where you're at the very limit of your capabilities, hanging on by your fingernails, I find that having closer ratios helps a lot to keep you in a pocket of cadence *and* torque that's manageable. It really sucks to be just hanging on and then find that you're straddling a gap where the cadence is a little too high with one cog and the torque a little too high with the other. This is, obviously, just my experience and can't speak to the sensitivity of others with regard to this.

In terms of largest cog, I'd take a look at both the length and steepness of your climbs. I live in a relatively flat area, but there are some steep pitches. That said, I can usually power my way up and over the vast majority of them within a handful of minutes.

Because of my terrain and riding habits, both with solo and with the group, I prefer tightly spaced cogs and have been riding with a 50/34 and 12-25t for the last few years.

DaveSSS 

Percentage difference between the sprockets is what matters. Shimano has a horrible 11-34 with large 11-13-15 jumps from the start, where it should be 11-12-13-14. Campy does it right, with as many small changes as possible, and larger changes only in the largest 3-4 sprockets.

My sram axs 10-36 cassette is OK, but not perfect. It doesn't have a 14. It should be like Campy's 9-36 13 speed, without the 9. 10-11-12-13-14-16-18-20-23-27-31-36.

Ataylor

Got it! Makes total sense. Thanks a lot for helping me understand that.
Yea', I have a bike and was upgrading to Di2 Ultegra. My previous groupset always had issues with the shifting and was actually defective right out of the box.

I honestly don't know how to describe my riding style. I wouldn't say that I'm a "strong" rider. I like longer rides. 6+ hours. I'm never really riding at a consistently fast pace. I don't ride in groups. The majority of my rides are usually pretty casual (I'm averaging about 17 mph), though I do speed about 20-30% of the time? And during those times, I'd like to experience shifts that are not disruptive - at least less so than other cassette's.

I'm mainly in the top sprocket of a 50/34 chain wheel, but with regard to the cassette, though I honestly never paid super close attention to any of this, I believe I lingered in the 14 to 25 range most of the time and, as mentioned, took advantage of the 32 cog from time to time. I just don't know how big a difference there would be on a 20% incline between the 32 and, say, a 28 or a 30T cassette and whether or not that difference is worth it to me.
Thanks for elaborating. It does help me see things much clearer now.

I may be wrong and might even wind up regretting my choice, but I just feel like this more than likely will be the case for me. I don't have many climbs and the one's I have aren't that steep.

I'm starting to lean more towards a 28 myself right now, but still on the fence. Will have to think about this some more.

Okay, I get it now. Thanks! So the gaps in between an 11/30 are slightly shorter than the 32.

28: 11, 12, 13, 14, 15, 17, (1) 19, (1) 21, (1) 23, (1) 25, (2) 28

30: 11, 12, 13, 14, 15, 17, (1) 19, (1) 21, (2) 24, (2) 27, (2) 30

32: 11, 12, 13, 14, 16, (1) 18, (1) 20, (1) 22, (2) 25, (2) 28, (3) 32

I guess there might be a slightly less noticeable (slightly less disruptive) shift with the 30T than there would be with the 32 (and maybe even ore so with the 28 vs the 32), since there's up to three spaces on the 32 (in between 28 to 32) and from one to two with the 30. And with the 28 there's only one space starting from 15 to 25 and then finally two spaces that happens once right at the very end, where it jumps twice from 25 to 28.

I guess this is all boils down to preference and what I'm willing to sacrifice for the sake of potential gain in smoother (or less disruptive) shifting. Might just have to test ride a 28 when I get a chance. Probably not too many hills around my LBS's, but it's the only thing I can think of that might giving me a better, experiential understanding of the differences.

Ataylor

Couple more questions for anyone willing to answer:

1) If I went down to a 28T cassette, could a different crank size make up for the "loss" of the cassette (i.e. going from 32T to 28T)?

2) If I did decide to go to a lower-sized cassette (it'll definitely be either 28 or 30), is there any advantage to using the shorter (SS) derailleur vs the longer one (GS)? I was told I could just use the long version, but I wonder if there's any benefit at all to using the shorter cage?

jaxgtr

I run 14-28 on my Domane and ALR as I am in Florida and have no hills. I do have plenty of wind. I like the close spacing due to the wind, so some days, a 16, 18, or 20 tooth cog, might be more comfortable than a 15, 17, or 19. I rarely if ever ride in the 11,12, or 13 tooth cogs, so they are wasted on me, and I have no worries of running of out gears going downhill on a bridge that is at max, 110 ft.

If you are 95% flat, you might look into the 14-28.

Ataylor

Whoa. That's interesting. Never heard of the 14/28. Judging by what I read on a forum or two just now, that sounds like a dream, but I wonder: how much of the speed aspect do you think you've sacrificed for the smoother shift? Is it a noticeable difference? Or negligible? Or has it been so long that you don't remember?

Iride01 

Google for bicycle gear ratio calculators. Look at the ratios, speed at cadence and other stuff. They'll help you see where you might get some benefits. But know what your own current bike does for you and what gears you normally use on it to climb or cruise. Then you can makes some assumptions about what changing things up might do for you.

I go to this site quite often, https://www.bikecalc.com/gear_ratios but it shows you gears that you don't have when it calculates. I've used a lot of others too, but keep coming back to this one.

You want your 1 tooth splits to be in the gears you use the most. For the extreme low range that is for those hills you seldom encounter, you can do with many more teeth between cogs.

woodcraft

The difference between a longer crank and a short one is similar to one lower gear, but crank length choice is more relevant to riding position, leg length, etc., or mainly what happens to be on the bike.

A 28t cassette can use a short cage RD for slightly snappier shifts and a few grams lighter, but the GS one preserves the option to put a larger cassette on if you want.

For the overall question, IMO the need for tighter ratios only shows up when riding fast with a group. On your own or with cadences < 85 or so it doesn't matter.

jaxgtr

I don't give up that much in speed on the flats, I typically am riding solo and avg 17-19 mph, and in groups, I can hang with the 24-26 mph using my 14-15 cogs on my 50/34 setup and for the vast majority of my riding, I live in the 16-20 tooth cogs. I am 56 yrs old now and speed is not my major concern anymore, I just turn the pedals and and enjoy the ride. When I was younger, I used a 12-23 9 speed cassette, this cassette reminds me of it obviously due to the corncob effect. The only time I use the 28 is on one of the bridges downtown as it has a 7% incline on one side and 8% on the other. The other bridges in the area are 3 to 5% max and I generally can get over them using the 23 or 25 in the big ring up front.

jaxgtr

+1 on the long cage....I have that setup, gives me flexibility to change out cassettes when I venture to hilly areas to put on a 30, 32, or 34 tooth cassette if I want.

Sy Reene

Not to add to your list of considerations, but while people say they never use the 11, 12, 13 - and this could be true, also realize that with a 14-28 you'd also be losing the 12 and 13 which might well have been usable when you're adding speed while still in the small front chainring, At a cadence of 90rpm that's in the neighborhood of 18-20mph speeds. (The 11 probably would have been off limits anyway due to too excessive cross-chaining).

With a 14-xx cassette, your usable top speed will likely be in the 15 cog while in the small chainring. That same 90rpm means topping out at 16mph where a shift to the large chainring becomes necessary.

jaxgtr

Yep, true, however, if you are looking at this cassette and live in a flat area, as I do, the small ring is probably not a huge concern, but you are correct and that should be considered if in a more hilly area.

Random11

I went from an 11-34 cassette to 11-28 with no real "science" behind the switch--just experience. I wasn't using the big cogs on my cassette so my 11-speed cassette was effectively an 8-speed or so the way I was using it. So, I got rid of the cogs I wasn't using and in exchange got closer spacing for the ones I was using. It's definitely an improvement having more closely-spaced gears, and now I'm using all 11 of them.

aliasfox

Best advice would be to go out for a ride. Find an area where there’s a gradual descent or a decent tailwind, shift into the gear you like, and see what cog you’re in. Then find the biggest hill you’ll ever take on, shift into the gear you like, and see which one it is. Practically, that will likely be the extent of your range -maybe add one more on either end for a bit of extra range?

I have a bike with a 52/44/32 triple in the front and a 12-27 nine speed in the back, and I have a bike with a 50/34 11-34 eleven speed. The gaps created by the 11-34 are very noticeable to me coming from the 12-27, to the extent that I am likely to switch to an 11-30 to have smaller gaps in cadence. The biggest hill around here is less than 7%, and I think I’ve only ever used the 32 and 34 cogs by accident. Conversely, I’ve taken the other bike up a 13% grade and could have used more than my 32-27 gearing allowed for.

Drew Eckhardt 

There are fewer situations where one cog offers a bit less resistance than you like and the next a bit more.

I think cassettes with more than a two tooth jump before the 19 cog are unsuitable for road riding. With 10 cogs I ride 13-14-15-16-17-18-19-21-23-26 and with 11 it would be 12-25 switching to a 46T big ring.

In the 8 speed era I paired a 50-40-30 triple crank with a 13-14-15-16-17-18-19-21 cassette providing a 13-19 straight block for plains rides east of Boulder, CO and low like 42x28 mountains west.

Eddy Merckx dominated the pro peloton with a 52x13 and I didn't need a gear bigger than he used.

SoSmellyAir

This is one of the reasons why I decided against a 14-28 cassette and chose a 12-25 cassette. With 50/34 chain rings on 105 (5800) derailleurs, the two smallest (12T and 13T) cogs are not useable when on the small chain ring, and there is still slight chain rubbing on the third smallest (14T) cog. So the 15T cog is the smallest cog I would use. Adjusting the L and L trim positions of the front derailleur did not alleviate this issue. I can use all cogs when on the big chain ring.

Ataylor

Thanks for the link. I'll check it out.

Got it. Thank you.

Why is that? What's the reasoning behind this? Less stress on the components at the cost of a more noticeable shift?

I assume by "length" you mean the crank arm itself (which, in my case, would be 172.5mm), right? But what exactly do you mean by "longer crank?"

Gotcha! Thanks a ton for the info. I appreciate it.

Oh, please do. I love hearing everyone's views. Plus, it's a very relevant point you bring up. Sure I want smoother shifts, but at what expense? How much of the speed is actually sacrificed and is that sacrifice really worth losing those 3 cogs? At this point, honestly, I don't know. I'll have to go on a quick ride to test out the gears and see which I use most and decide then.

Thanks a lot for sharing. Before I really started to visualize what everyone was talking about, I'd assumed this theory was either going to be wrong or at least very polarizing. I'm surprised that it's not and very happy that I learned about it.

The one hill that has the steepest incline is way too far for me to ride to, since it's still pretty cold in my area. I'll definitely try to sneak a quick test ride into my schedule and figure out how often I use the 11-13 cogs. I don't know if I've ever really paid attention, so that'll be pretty interesting to figure out.

Yea', I don't know what I was thinking. As mentioned above, I think there's only one hill I can think of in my area that's steep, so having a 32T cassette boiled down to nothing more than ignorance on my end.

Thanks!

I'll keep that in mind. Thanks again.

Iride01 

Because you are making a compromise. if you want to be able to ride up that 20% grade or what ever grade is difficult for you, then you can't just have one tooth gaps from 11th to 1st gear. At some point you have to accept more than one tooth gaps and the potential of ever so slightly worse shifting or drastic change in gear ratios.

Unless of course you have say maybe a 32 speed rear.


(I pulled 32 out of my ...... so don't dwell on that specifically)

SoSmellyAir

It is simply math. On the small end of the cassette, a single tooth makes a big difference, e.g., 12/11 = 1.0909. This means you have to increase your cadence by about 9 percent to maintain the same speed after shifting from the 11T to the 12T cog. This differential decreases as you move toward the big end of the cassette, e.g., 13/12 = 1.0833, 14/13 = 1.0769, etc. At some point it becomes pretty small, e.g., 19/18 = 1.0556, so it makes sense to have a two teeth jump. At the big end of the cassette, where one is generally climbing and thus going slower, one can tolerate a bigger, multiple teeth jump in order to have a bigger mechanical advantage to climb steeper slopes, i.e., a bail out gear. For example, the 7 speed cassette on my wife's cruiser bike has two teeth jumps throughout except the largest cog is 10 teeth larger than the next largest cog. But she never uses it.

Iride01 

Is that for my benefit or the OP's?

I already knew what you are trying to express, but I didn't think it quite material to what I was attempting to convey to the OP. However the OP does need to realize that.

SoSmellyAir

I was merely trying to articulate the mathematical basis for what Iride01 explained above to the OP.

socalrider

If you want to do the deeper dive you can use the Sheldon grown gear calculator and you can see where the overlaps are from big to small ring. If I have a very flat ride - I will put on a 12-23 cassette which gives me a super tight shifting ratio. If I am climbing then I opt for a 12-27 or even 13-29 cassette - depending on how many climbs are over 10% grade. If you are using Shimano or Sram - you do not need to buy Dura Ace / opt for Ultegra or even 105 cassettes to save you money. The other thing is that many do not really need an 11 cog - start your cassettes with a 12 or even 13 if you are climbing a lot those days.

https://www.sheldonbrown.com/gear-calc.html

SoSmellyAir

I use this gear calculator:

Bicycle Gear Calculator (gear-calculator.com)

You are preaching to the choir. The ideal cassette for my local terrain, my 50/34 chain rings, and my general lack of fitness would be a 12-28 cassette. But this Goldilocks cassette is only available as a Dura-Ace. That is why I have an Ultegra 12-25 cassette, which offers closer ratios, but require me to shift onto the small ring when I am coming to a stop when going even slightly uphill. These posts detail how I tried but failed to make my own 12-28 cassette.

Bike Forums - View Single Post - Custom 12-28 cassette
Custom 11-Speed Ultegra 12-28 Cassette? - Bike Forums