/n/ - Transportation » Thread #1588489

[19 / 2 / ?]

105KiB, 1000x600, -S1D34OlhsCCdGUAiVUwUTeXY.jpg

No, I'm not talking about cassette range

Anonymous Tue 22 Dec 2020 16:11:16 No.1588489 View View Reply Original Report

Quoted By: >>1588509 >>1588548 >>1588559 >>1588712 >>1588828 >>1588959 >>1588999

What gear ratios do cycling pros normally use, and is there a one size fits all approach?

A Shimano 12-28 10-speed will consist of cogs 12-13-14-15-17-19-21-23-25-28. Old-fags glorify the 16-tooth cog, and will sometimes swap out individual cogs to get a nice 1-step range from the smallest cog upwards for around 5 shifts.

Do the pros replicate this, and how does it benefit an unracer? Does the jump from 15-17 leave much to be desired?

Anonymous

Anonymous Tue 22 Dec 2020 16:58:34 No.1588505 Report

Quoted By: >>1588527

Why the fuck do you think that’s relevant to you?

Anonymous

Anonymous Tue 22 Dec 2020 17:01:31 No.1588509 Report

Quoted By: >>1588527 >>1588559

>>1588489
Tooth counts on cassettes are chosen to keep the cadence jumps between gears across the whole cassette as even as possible for the given largest and smallest cog sizes. Mathematically that means the tooth counts should be in geometric progression, but because they must be integers it can't be exact so there's some amount of unevenness (in this case especially at the 14/15/17 area, which ideally would be roughly 14.5/16/17.5). The standard choices optimize the whole cassette, so trying to tighten up one side just means you'll have to make the rest even worse, so it doesn't make much sense unless for some reason you're only using half of the cassette to begin with.

Anonymous

Anonymous Tue 22 Dec 2020 17:26:00 No.1588527 Report

Quoted By:

>>1588509
Thank you for the concise and relevant answer unlike >>1588505

Anonymous

Anonymous Tue 22 Dec 2020 17:51:01 No.1588548 Report

Quoted By: >>1588554 >>1588555 >>1588556 >>1588559 >>1588813

>>1588489
Tighter spacing on the small cogs and a little bit bigger jumps on the big cogs is generally how cassettes are put together, Shimano has had some retarded ideas with some of their offerings though imho, their 11-34 11 speed cassette is one that comes to mind. 2 tooth jumps starting at the 11t cog just doesn't make sense to me, especially on 11-34 which will probably be paired with a 2x crank on a more road focused bike. What do the pros do? I have no idea. Myself, I've moved from using all 11-28 to 11-30 cassettes because the two are identical until you hit the 3rd largest cog. Instead of the old 2-2-2-3 jumps, I now have 2-3-3-3. I really can't tell the difference between the two in practice.

Anonymous

Anonymous Tue 22 Dec 2020 18:09:38 No.1588554 Report

Quoted By:

>>1588548
Good thinking, if I was doing a sustained effort over flat terrain a 11-23/25 will make more sense over a modified 11-28 with exponential gearing. I can see why shimano went with 1-1-1-1-2-2-2-3-3

Anonymous

Anonymous Tue 22 Dec 2020 18:13:45 No.1588555 Report

Quoted By:

>>1588548 #
Good thinking, if I was doing a sustained effort over flat terrain a 11-23/25 will make more sense over a modified 11-28 with exponential gearing that starts only from the middle cog. I can see why shimano went with 1-1-1-1-2-2-2-3-3 jumps, my old cassette offered a 12-14 jump that did not feel good at all. Plus it was too big for the derailleur.

Anonymous

Anonymous Tue 22 Dec 2020 18:15:27 No.1588556 Report

Quoted By:

>>1588548
Good thinking, if I was doing a sustained effort over flat terrain a 11-23/25 will make more sense over a modified 11-28 with exponential gearing that starts only from the middle cog. I can see why shimano went with 1-1-1-1-2-2-2-3-3 jumps, my old cassette offered a 12-14 jump that did not feel good at all. Plus it was too big for the derailleur.

Anonymous

Anonymous Tue 22 Dec 2020 18:30:57 No.1588559 Report

Quoted By: >>1588623

>>1588489
Pros go faster than oldfags do they don't hover around the 16t.

>>1588509
False, many cassettes are designed to have tight jumps at the top end and larger jumps at the bottom end because high speed aero drag gearing considerations are different from low speed climbing ones. The reason Shimano goes for even spacing is because it shifts better.

>>1588548
Or you could just buy SRAM/Microshift cassettes.

Anonymous

Anonymous Tue 22 Dec 2020 21:12:50 No.1588623 Report

Quoted By: >>1588827

>>1588559
>Microshit cassette
Worst product I've ever owned. Will never purchase again.

Anonymous

Anonymous Wed 23 Dec 2020 00:20:42 No.1588712 Report

Quoted By:

>>1588489
Depends on what the elevation change is for a stage/race. On the flatter side they will go for smaller cassette range to get smaller jumps between gears. On the hillier side they will go for a wider range so they can actually get up the hills. Some pro racers/teams are known for ditching dura-ace cassettes for ultegra on hillier stages/races because it does not give them the desired range.

Anonymous

View Same Google ImgOps iqdb SauceNAO Capture.png, 31KiB, 337x702

Anonymous Wed 23 Dec 2020 04:11:04 No.1588813 Report

Quoted By: >>1588839

>>1588548
They assume if you're a pussy who's buying a 34 cassette in the first place that you'll never use the harder gears anyway so they pretty much fuck everything below 17t and hope you never notice.

Anonymous

Anonymous Wed 23 Dec 2020 04:45:34 No.1588827 Report

Quoted By:

>>1588623
You haven't tried a DNP cassette

Anonymous

Anonymous Wed 23 Dec 2020 04:46:25 No.1588828 Report

Quoted By:

>>1588489
>how does it benefit an unracer
anything above 9 speed is racer. unracers should go for 11-34 8sp or 11-36 9sp.. While it is pointless to have that many gears in the back, you want that 34,36t so you can go really slow without having to buy a fancy wide range 42t+ cassette. then it's all a matter of getting a good 22t or 24t granny gear if you need it. of course if you don't need the range a good old 32t x 11-34t is typically all you need in a city.

Anonymous

Anonymous Wed 23 Dec 2020 04:54:11 No.1588839 Report

Quoted By: >>1588847

>>1588813
My strongest suit isn't math, what formula did you use to get the same ratio across the two ranges? How does absolute sum help?

Anonymous

Anonymous Wed 23 Dec 2020 05:16:14 No.1588847 Report

Quoted By:

>>1588839
The second two columns are a measure of how far the gearing is from ideal. Second to last is cumulative sum of the absolute differences of the actual ratios from the ideal ones, and last is the same thing but each difference squared.

Basically

Speed = Gear Ratio x Cadence x Wheel Circumference

So if you're maintaining a set speed and not changing gear in front

Back Gear Size = Cadence x Some Fixed Number

Changing to a gear with X% more teeth (multiplying left side by 1.0X) means your cadence (right side) needs to go up the same X% to compensate. If you want that X% to be the same across the whole cassette, the ratios in the number of teeth between adjacent gears needs to be the same. This isn't technically possible since gears need integer numbers of teeth, so you find a set that's as close as you can get, for some definition of "close".

Anonymous

Anonymous Wed 23 Dec 2020 14:29:20 No.1588959 Report

Quoted By: >>1588965

>>1588489
Shimano makes a 12-27 cassette with 15-16-17, but it's only available in dura-ace. As for cog jump ratio, Sheldon Brown's gear ratio calculator works fine. You could even print it out and stick it on your stem if you like to roleplay.

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

Anonymous

Anonymous Wed 23 Dec 2020 14:49:37 No.1588965 Report

Quoted By:

>>1588959
>i need to load up a website to calculate 17/16 for me

Velo Uber Alles

Velo Uber Alles Wed 23 Dec 2020 15:52:10 No.1588999 Report

Quoted By:

>>1588489
>What gear ratios do cycling pros normally use,
Lets simplify this by looking at dura ace.
55-42T, 54-42T, 53-39T, 52-36T, 50-34T

11-12-13-14-15-16-17*-19*-21*-23*-25*T
12-13-14-15-16-17-18*-19*-21*-23*-25*T

11-12-13-14-15-17-19*-21*-23*-25*-28*T
12-13-14-15-16-17-19*-21*-23*-25*-28*T

11-12-13-14-15-17-19*-21*-24*-27*-30*T

>Ultegra for mountain stages
11-12-13-14-16-18-20-22-25-28-32T

>and is there a one size fits all approach?
No. Keep in mind that interchangeability and neutral wheel support is also a thing. There's a difference between courses, and rider power, rider weight. Just look at the differences in front gears.

The general idea is a lot of small gaps in a range where you're going to be spending a lot of time, near the top of the the range you would use.

Unracers with heavy bikes, heavy wheelsets, and potentially lots of cargo shouldn't be blindly copying numbers. Calculate out your desired range, based on your estimated power, or practical experience on what gears you like.

Capcode	All Only User Posts Only Verified Posts Only Moderator Posts Only Manager Posts Only Admin Posts Only Developer Posts Only Founder Posts
Show Posts	All Only With Images Only Without Images Only Spoiler Images Only Non-Spoiler Images
Deleted Posts	All Only Deleted Posts Only Non-Deleted Posts
Ghost Posts	All Only Ghost Posts Only Non-Ghost Posts
Post Type	All Only Sticky Threads Only Opening Posts Only Reply Posts
Results	All Grouped By Threads
Order	Latest Posts First Oldest Posts First

On these archives

Your latest searches

No, I'm not talking about cassette range