Seattle Forrest

For TT. To reduce drag, at the crank and by removing a shifter. I don't know how big a deal that could be, marginal gains I guess.

https://cyclingtips.com/2020/04/roto...y-power-meter/

Cyclist0108

I still haven't finished hating 12 speeds.

base2 

It's been out a while now.
I saw it when searching out their Qarbon oval rings. (I have 1, the rest are Absolute Black for a reason.)

Have you seen the price? All for an extra cog or 2 Yikes!
I'd like to know their sales numbers.

ShelBroCo already had the right idea years ago.

This is getting ridiculous.

Kimmo 

Don't forget being the only guy in your city with hydraulic shifting...

nomadmax 

It all came to a grinding halt with 2x10 for me. I have enough spare parts to make it all the way to the finish.

Drew Eckhardt 

Unfortunately they don't sell a cassette suitable for road riding. The tightest is a 10-11-12-13-14-15-17-19-21-24-27-31-36 with no 16 cog. Aftermarket alternatives like a 10-32 with a 16 and 10-28 with an 18 are unavailable, and once you do that you no longer have the range you could have with a double.

Seattle Forrest

I don't know why you'd need a 36T in a TT? Aren't they generally flat?

Drew Eckhardt 

That's the smallest 13 sped cassette Rotor sells. You can have 10-36, 10-39, 10-46, or 10-52.

You get a 31 and 36 cog you don't need, but 15-17-19 cogs in the middle with no 16 most roadies want and the 18 a significant minority like.

10-11-12-13-14-15-17-19-21-24-27-31-36
10-11-12-13-14-15-17-19-21-24-28-33-39
10-11-12-13-15-17-19-22-25-29-34-39-46
10-11-12-13-15-17-19-22-26-31-37-44-52

Jasper Storm

Biggest marketing joke in some time.
The only racer showing up at a TT with any of those setups is grinding his/her teeth at being that beholden to their sponsors.

znomit

If you dig deep I think you'll find there's room in your heart to hate both.

AlmostTrick

Sounds unlucky.

Racing Dan

The "missing 16" sort of depends on your perspective. I doesnt have a 16t cog, but with a 10t you likely would use a smaller chainring. >

44t + 10-36 vs 50/34t + 12-28. Both combinations have 1t spacing in the 79" to 120" gear inch range. And a bottom gear at about 33".

Bicycle Gear Calculator

Kimmo 

I hate on 11. Moving the drive side flange wasn't necessary.

Drew Eckhardt 

It's about percentage change, not one tooth specifically. That holds regardless of gear inches.
11/10 10.0%
12/11 = 9.1%
13/12 = 8.3%
14/13 = 7.6%
15/14 = 7.1%
17/15 = 13.3%
19/17 = 11.7%
21/19 = 10.5%

People are more sensitive at high speeds where power increases almost with velocity cubed, versus climbing where it's linear.

I'm in the minority believing 52x13 was a big enough gear for Eddy Merckx to dominate the pro peloton, I'm not Eddy, and 50x13 or 39x10 would be sufficient; although that's still a 19 MPH gear.

With time trial riders typically more likely to use a 53x11, they might run a 48 making the 16 cog a 23+ MPH gear.

Those are definitely in the power increasing with cube of velocity area where that jump is objectionable to many people.

I wouldn't pay money for a bicycle that didn't have one tooth jumps to the 19 cog because when riding at a reasonable pace that feels like something missing. I don't feel that way about the 19 to 21 gap, and while I noticed a difference with a 20 cog it wasn't worth the extra cog change arriving at the next gear switching rings.

That seems to match the graphical representation where missing 16 and 18 cogs leave holes between adjacent gears (50-34 rings x 13-23 9 cogs):

Drew Eckhardt 

I can see the appeal of hydraulic shifting.

Moving to under-tape cable routing having hoods level with bar tops cut rear shift cable life in half. I need to replace mine every 2000 miles to avoid breakage and would avoid that with electronic.

Electronic needs to be charged. Hydraulic avoids that.

The one ring limit, cassette options, and proprietary hubs are all show stoppers for me.

Homebrew01

Do chains ever come off single chainrings ?
My winter bike had a double but no front derailleur, and it occasionally jumped to the big ring, when in the smaller cogs, and a few times then jumped off the big ring to my pedal.

Kimmo 

Yeah, I reckon 10t and 11t blows not just because of chordal action, but mainly because the percentage jumps are too big at that part of the cassette.

IMO achieving a more optimal ratio curve is the lowest-hanging fruit left on the efficiency tree now that aero is pretty much covered. And perhaps you could get a smidgen more biomechanical efficiency by eliminating rocking torque between foot and pedal spindle by revisiting Shimano's dropped pedal idea from the 80s, but that kind of requires frames with higher BBs, let alone a better bearing system for the pedals...

Anyway, closer ratios at speed. There are two ways to approach it within the confines of a derailer chain drive: shorten chain pitch or add more rings. The former would be a big deal, and something tells me half-inch is probably pretty damn close to ideal for this application given all the relevant constraints and compromises anyway.

So, adding rings. There's not much room, especially if you don't want to go and widen Q like on a triple... But, I figured out how to do it, and mocked it up (there's a link in my tag to a thread about it, visible in desktop mode). The trick is to go for a half-step triple, which allows the two big rings to be quite close. This puts the small ring only a mm or two inboard, and the outer ring is about the same amount outboard from a double. It fits on a double crank, even a 130mm BCD.

Cause here's the thing about the ratios - I did a spreadsheet to try a whole bunch of combos (it should be attached to that thread IIRC), and it turns out that it's actually quite hard to find something that gives you a nice smooth curve with consistent jumps. In fact, there's only one combo that looks good - 38/50/52. And it looks great! If you think this sounds a bit odd, grab the spreadsheet and chuck some different ring sizes in it and see; it's almost uncanny. So it'd sure be nice to eliminate mucking around with different niches to cover at the front, and just address differing needs with different cassettes...

Anyway, this whole half-step triple concept wouldn't even be on the table if it wasn't for electronic shifting; you wouldn't bother with the faff most of the time. But I reckon if Shimano picked this up and developed it to meet their standards, it'd be the tits.

HTupolev

There's not a whole lot of need to "widen Q like a triple" for most triples in the first place. Most road bikes can fit a 142mm double no problem. Even if we merely add a chainring to the outside and don't bring the tiny small ring inboard at all, that's only 5mm on the drive side. So 147mm is no problem. Even if we decide to listen to the people who think that Q needs to be symmetric, we add 5mm to the NDS and we're still at 152mm. Yet tons of triples have a Q-factor all the way out at around 160mm for some reason. It's ridiculous.

You can use a much wider-spaced cassette to ensure more even jumps across the range by eliminating the transition from 1T to 2T jumps. Most people are comfortable with the 1-tooth jumps through most of the straight block, the issue is when the jumps get much above 10%; by starting at 2-tooth jumps and half-stepping everything, you can keep all of the jumps comfortably non-huge.
For instance, consider 52-48 paired with 11-13-15-18-21-24-28-32-37-43-50. The biggest jump is 10.8%, but otherwise everything is around 9% or less. Or you could go something like 11-13-15-17-19-22-26-30-35-41-48 and keep everything under 9%, but you'd end up with a couple of ultra-small (3-4%) jumps in there that some people maybe wouldn't like. Either way you've got 22-ish unique useful ratios on a 2x11 double, with a top-end just as high as a modern road drivetrain and a bottom-end of around 1:1. There are a lot of possibilities.
Of course, going with a wide-spaced cassette does have the drawback of a heavy cassette with a lot of rotational momentum.

Kimmo 

Yeah, that's interesting, except those points you note, and perhaps most important, that huge cassettes are fugly as hell. It nicely emphasis a benefit of my gearing concept - existing cassettes are utilised.

All it needs is the crankset (or even just rings made to fit on a standard double), a specific FD cage, perhaps a mite more travel in the FD (mainly just to maintain adjustment headroom - a FD-7700 had enough travel), and the software (I actually wrote arduino code to shift this system using servos pulling short cables, but the need for a bespoke FD cage killed my little project... also the flex in the middle ring thanks to a tortuous load path through a 110/130 small ring... oh, and a lack of appropriate shift profiling on the rings. But I established the packaging works, anyway).

I'm like 75% sure this fruit will be picked within the next 15-20 years (likely a bit sooner - that is, assuming we stick with half-inch pitch and derailers, and Shimano could make it manage simultaneous front and rear shifts with close enough to 100% success). And it'll be 38/50/52.

Drew Eckhardt 

No.

Rotating weight doesn't matter unless you're a marketing department selling to people who won't do arithmetic or you're a competitive sprinting specialist who might win by six inches and it's actually a lot of rotational momentum in your rims/tires.

Total weight of this magnitude only matters if you're a competitive climbing specialist racing in the mountains.

Either way you need a great training program and good genetics which few people have before it's an issue.

A rotor cassette weighs 236 (10-36) to 321 (10-52) grams with large cogs made from aluminium. You can assume an increase of the entire weigh at the big cog circumference which is larger than my example by a factor of 52/45, double velocity, increase RPM an additional 7% for 25mm road tires, and it still won't be significant.

https://www.quora.com/Are-12-speed-m.../Drew-Eckhardt.

An XTR 10–45 12 speed cassette weighs 376g which is 45g heavier than a 331g XTR 11–40 11 speed cassette.

Bike plus rider weigh about 70kg (154 pounds) when you’re not too big to be a climbing specialist and ride a bike suitable for races with mountaintop finishes.

The impact of weight is proportional to the total. 45g/70,000g = 0.06%, or 2.2 seconds per hour of climbing up the steepest grades.

Rounding a pleasant 20 MPH up to 9 meters/second, it has 0.5 * .0045 * 9^2 = 0.18 j of kinetic energy at that speed.

With 50mm ISO 622 (29er) tires for a 722mm outside diameter, your cassette is turning 4 revolutions per second or 8 pi radians per second.

A 1/2″ pitch 45T cog is 7.17″ in diameter, or 182mm. With the new mass at its outside diameter, its moment of inertia is 0.0045 kg * 0.091m^2 = 0.000037264 kg m^2.

.5 * 0.000037264 * 25 rad/second^2 = 0.01 j, bringing the total energy added by that weight increase to 0.19 j.

At 20 MPH riding a road bike on pavement you’re using about 35kj/mile which is 22j/meter. 22j / 0.19j = 0.009 meters.

Your move from 11 to 12 cogs increases the energy accelerating that speed to what it takes to cover 9mm - about 3/16″.


https://www.quora.com/Does-upgrading.../Drew-Eckhardt

Rotating weight is only a theoretical concern. If that 500 g was where the rubber meets the road it would count double accelerating for up to 1.3% of total kinetic energy. However, accelerating that rotating weight from 0–20 MPH takes only 2 (kinetic energy rotating + in a straight line) * 0.5 kg * (8.9 m/s)^2 / 1000 kj / j = 0.079 kj which is what you spend covering 12 feet at 20 MPH requiring 35 kj / mile.

Reducing rotating weight can make you slower when it comes with an aerodynamic penalty, even in the mountains. With a 170 pound rider producing 250W taking 1:09:44, shallow 1100 g wheels where “The aerodynamic properties given to this wheel were that of a common training wheel like a Mavic Open Pro. “ would be 2 seconds slower than a 1624 g pair with more aerodynamic 30mm aluminum rims up the 8.2 mile l’Alpe d’Huez climb .

base2 

Every pedal stroke is a tiny accelleration.

HTupolev

Sorry, I should have been clearer... I wasn't referring to the effort to accelerate the bike, but rather, to the effect that cassette inertia has on drivetrain behavior. When you're in a small cog and suddenly stop your pedaling, the cassette - which is still spinning forward - has a lot of leverage on the chain. If the cassette has a lot of rotational inertia, it can kick quite a bit of chain from the lower run into the upper run before it finally comes to a stop. This makes the upper run of the chain go slack, and generally feels kind of sloppy when it happens.

I was basically trying to compare the merits of Kimmo's half-step-plus-granny arrangement versus other sorts of gear-interleaving arrangements that could be feasible today.

That's not really relevant. An object with more inertia is slower to accelerate when a certain amount of power is applied, but it is also slower to decelerate when power is removed.

Racing Dan

Yeah, weight is highly overrated.

Every additional 100 g takes a measly 0.27 W if you a ascending at a brisk 1000 m per hour. That is less than 3 W for 1 additional kg. Half that if you are "only" doing 500 m per hour.

Drew Eckhardt 

Energy can't be created or destroyed, only its form changed.

You only change a tiny bit of energy expended accelerating into heat through rubber hysteresis, metal on metal friction, and aerodynamic drag.

The rest becomes kinetic energy that keeps you moving forwards producing slower deceleration through the weak spot in your pedal stroke.

Greater inertia actually increases mean maximal power for many people whose output measures higher outdoors on flat ground than climbing or indoors because it reduces the impact of their dead spot.

While not enough to carry you any appreciable distance up the next incline in rolling terrain, it will get you through the 0.005 to 0.010 seconds until you're pushing down with your other foot.

https://towardsdatascience.com/machi...1-2abb04b30036

base2 

A) I was trolling the exceeding amount of math.
B) It was fun.
C) There really isn't much of a push in the cycling world for fly-wheel wheels. Which the claims: "weight does not matter" and "it's not really lost" suggest there would be room for considering the broad diversity & competative nature of the industry.

Clearly, some feel weight, wherever it is located, matters. Even if it goes to subjective things like "feel."