Kapusta

If you are going to quote me, quote the whole sentence.....

smd4

So answer the damn question.

Kapusta

Your question is based on a faulty assumption.

smd4

Figures.

Iride01 

You seem to be imagining that I'm saying that.

Black wallnut 

Explain "near max effort dialed in"

AndreyT

Strange question, considering that the answer is rather obvious. Is this serious? Anyway, I'll bite...

I don't wanna write a tractate on that topic here, so I'll try to be brief:

1. The first technological development was not directly targeting big-big, but it was definitely its major technological enabler: expansion of the number of gears in bicycle drivetrains and accompanying progress in chain construction, which effectively eliminated the issue of excessive wear in cross-chained gear combinations. By the time 10-speed (or, perhaps, 9) drivetrains went into mainstream, the matter of wear, as well as chainline stability issues became ancient history. Skewed gear combinations no longer had any appreciable effect on the wear of the components or drivetrain stability.

2. The next technological development is kinda "on the nose": trim feature. The moment the issue of excessive wear went out of the picture, a different issue came into the foreground: purely spatial mechanical restrictions of FD-equipped drivetrains. Shifting to big-big caused rubbing between the chain and the FD cage, especially in case of short-chainstay frames. So, in their relentless quest for the Holy Grail of big-big groupset manufacturers introduced trim: a feature whose entire purpose is focused solely on enabling big-big. (And this is actually the part that makes me wonder why someone in a bicycling forum would express any doubts about importance of big-big. Have you ever heard of trim?)

3. Trim solved the interference issue, but this was still far from perfection. And that is when the money and effort thrown at polishing big-big finally resulted in an undoubtedly revolutionary quantum leap in the history of bicycle drivetrains: electronic shifting. Electronic shifting not only allows one to pre-program arbitrary per-cog custom indexing, but also potentially supports on-the-fly real-time-feedback-based shifting. This basically solves everything and eliminates all possible concerns. The quest for big-big is now as complete as it can possibly be.

smd4

Having a flexible chain doesn't obviate the fact that cross-chaining exists.

Yes. Trim. News flash: It's not new. It's existed on every bike I've ever owned. Nothing new to see here.

So nothing that you wrote disputes that cross-chaining still exists. And all the "technology" you think is groundbreakingly new, isn't. It's the same--A chain, running between two sets of gears, controlled by derailleurs. Thanks.

But if you have a source, I'd love to see something indicating that being able to cross chain was "the most important objective of all bicycle drivetrain design in the world for the last 30 years."

AndreyT

I'm not sure why you keep mentioning this. Of course, it exists. What does not exist is the issue of cross-chaning. Cross-chaining is not an issue anymore. It is not even "a thing" in 2023. We just use all available gear combinations without having to give it a second thought. It is as simple as that.

Well, just perceive me as that proverbial "horse's mouth"...

Eric F 

I've had some bikes more tolerant of cross-chaining than others. My race bikes from 20 years ago were fine, but then again, my largest cog was a 23, not a 29, which makes a difference in the distance between chainring and cog. My current #1 road bike complains pretty loudly about big-big, which is the combination with the most extreme chain angle. I get increased noise from the chain on the chainring (this actually starts being noticeable in the next-to-largest cog), from the cog, as well as from the inner plate of the FD. The Campy Record 11s shifters don't have the ability to trim the FD in the big ring like Shimano does. No, it's not out of adjustment. Yes, the bike is rideable when cross-chained, but it's clearly not anywhere near ideal, and it's pretty easy to avoid.

smd4

I wouldn't have to mention it if you hadn't written this: "there's no such thing as "cross-chaning" (and hasn't been since 1990s)."

Wrong end…

AndreyT

Well, it should be obvious to everyone (and I have already mentioned it previously) that one major factor that determines the degree of chain skew in big-big is chainstay length. The shorter the chainstay is - the more extreme the skew in big-big is. If you have one of those extreme racing "pooping dog"-style bikes where the rear wheel is purposely shifted way forward under the seat (and the bottom of the seat tube is shaped to accommodate that), then having some problems in big-big is understandable. But if you have a road frame with "traditional" geometry (16 inch-ish chainstay length) and still observe problems in big-big... well, something is likely to be out of adjustment in your drivetrain.

Eric F 

My bike is not anything unusual for a high-end road race bike, and certainly not extreme (405mm/15.94" chainstay). Nothing is out of adjustment. I'm not new to this.

smd4

Or he’s just cross chaining.

AndreyT

That's what "big-big" stands for, sweetie...

smd4

Eeew.

smd4

So then you agree big-big is cross-chaining, and that it can be problematic even on a well-adjusted bike?

79pmooney

??? Being in the slowest yet fastest gear at the same time? If I had to ponder that one, I would have been so confused I wouldn't have been able to pull off the move I did.

AndreyT

No, I don't know where you are getting this bizarre nonsense. As I clearly stated previously, cross-chaning is not a problem on a well-adjusted bike. And I stated this with authority, meaning I didn't really offer this for a debate...

smd4

It’s sort of shocking to me that people cannot understand this concept, and which led to my conclusion that lots of cyclists simply do not understand how bicycle gears work.

smd4

Authority? HA! A California software engineer who strips out QR nuts and has to ask strangers on the internet how to wear his sunglasses? You have no “authority.”

Iride01 

Poor choice of phrasing on my part. I was just trying to set up a situation where one might just shift to the big cog and just do one shift instead of having to shift the front once and the rear 2 or 3 times. Essentially I was attempting to describe a gear ratio that one could maintain comfortable while putting out a lot of power. Not a gear combo that one knows will have them tiring out before they reach the top.

Mr. 66

Oh crap, now that's some funny stuff.

HTupolev

This - and some adjacent subjects, like the merits or otherwise of 1930s racing derailleurs - is a topic covered by very little publicly available testing, and steeped in folklore. I'm surprised to hear that the answer is "obvious."

Changes to chain construction have primarily been about narrowing the exterior and improving shift quality, not improving performance in diagonal operation. It's possible that the increased lateral flexibility of chains has incidentally improved things in this latter respect, but this isn't a trend particular to just the past 30 years, and I wouldn't agree that modern chains have entirely eliminated it.

Of course, whether this is actually a problem is a separate matter. A watt or two isn't much, and higher wear rate on larger cogs can be amortized by their size, much as it is on chainrings: most cassettes under most riders wear out in the small cogs before the big ones. (This defense obviously doesn't apply to small-small cross-chaining.)

Prior to around 1990, front derailleurs were generally operated with friction shifters, so there had always been trim. Heck, some minimalist rod-operated FDs did not use significant friction to maintain position, and were consequently self-trimming.

Changing chainrings is frequently more disruptive to pedaling than changing a rear cog: this is due to the large ratio differences often necessitating compensatory rear shifts, the often slower mechanical resolution of the shift, and on mechanical drivetrains, frequently greater ergonomic effort due to the lever throw and force required to shift. If you can get up a hill using just the gears accessible to one chainring, it can be preferable to do so even if it costs a few moments of less-smooth-running chain operation than to involve the FD.

grumpus

It's not necessarily that simple: straighter chain line but with greater rotation of each chain link as it leaves and joins the smaller sprockets under load, at lower speed and greater load because chain tension is proportionally higher running 39/21 than it is running 52/28 although the ratio and force at the crank are the same. I wonder how that all weighs up.