Lakerat

Was imagining when companies like Shimano, Campagnolo, and SRAM decided to make electronic shifting systems. They could have hired electronics engineers or consulted with companies that already made them, or both.. Possibly the proper consulting companies would be those already making products using stepper motors like used in automotive throttle bodies. I think "stepper motors" is the proper term for electric motors that don't really spin continuously, but stop at a range of levels.

Know anything about how these companies dealt with the electronic aspect when developing these products since their engineers previous only dealt with mechanical devices?

spinnaker

What makes you think they don't have electronic engineers?

https://www.modernbike.com/sram-comp...-rate-monitors
https://www.pricefalls.com/product/c...76347360542896
https://www.pricefalls.com/product/s...75728885230148

Ironfish653

I can't believe I'm going to be defending engineers, but there's a lot more to making a product than just designing it. In most (large-scale) manufacturing operations, there are far more engineers dedicated to the equipment and processes that make the products than there are design engineers. Some of these guys are pretty smart. Just because you work on bicycle parts doesn't mean you don't know anything about robotics/automation, for example.

Besides, in the Di2 example, Shimano doesn't actually manufacture the stepper motor themselves. It's most likely produced by someone like NGK, Denso or Bosch, who specialize in that sort of thing. Shimano just gave them the specs for what they needed.

Besides, when you're doing proof-of-concept, you usually start with off-the-shelf parts and components, modified to do what you're trying to achieve. This is the Frankenstien workbench stage; It's not a usuable protype yet, but it just proves that you can make it work at all. Then you refine the POC to determine the actual requirments (force, power supply) the prototype will need, and how to make it fit within the constraints of your project.

Road Fan

I can't say what they actually did, but from my 35 years in vehicular electronics I can offer a few thoughts. To actually know the answer to your question, one would have had to work for one of teh companies, and what actually happenned would have been confidential information. The systems perspective had to be established first, and the makers of 8/9/10/11 mechanical indexing systems already knew this part - how much to move the mech for each desired change, given the target positions of the rear and front chainrings, and how to figure in needed over shift and fadeback motions. These spacings and motion increments may have dictated stepper motors or not. Steppers increment a shaft by a certain number of degrees on each step, normally. If the cassette really has even pitch between adjacent then perhaps a stepper is good, but it stepper rotor pole piece systems don't accommodate all spacings and angular increments: it may also have needed a transmission of some sort to exactly match the motor steps to the mech. But then, what about changing the design from 10 to 11? The nominal step width and hence the rotary step must be decreased by exactly 1/11.

In any case, I would probably have begin to recruit for design capability in motor drives, power electronics, and system control algorithms perhaps 2 years before the product is planned for road testing. I'm certain consultants in those skill areas could have been found, but they may not have had bicycle component engineering experience.

As I alluded, I think these systems could have been designed based on any type of electric motor: DC, DC Brushless, stepper, or even variable reluctance. Some type of position sensor would have been needed for each of them but it might also have been needed for a stepper-based solution. The cost and complexity trade-offs should have revealed why the stepper (or other) was the preferred design solution.

Road Fan

I am an engineer and I hardly think I need defending, nor have any accusations been made. Many engineers view the design for manufacture and the product design as to be done at the same time (a form of "concurrent engineering"). Certainly they are different parts of the same project. You should have the manufacturing people "looking over the technologist's shoulder" from the beginning to be able to start thinking as early as possible about planning to manufacture this new product. In the automotive world, the manufacturing plant is the most complex machine in the system, so yes it has a lot of support functions and staff.

I think you're right on with the proof of concept discussion. One starting point might have been to simply add motors and geartrains to existing Dura-Ace or Super Record groups as sold. If I was on the project I would have started with as much as possible that is already known. But of course that would not be what you want to manufacture.

I do think it is not always the case that the design comes from refining the POC. Certainly one learns a lot from the POC, but it could well be that the next version will be a fresh start based on the total of what has been learned to date.

Ironfish653

I 've been a Set-up Tech, and then Production Lead for a little over 15 years, so it's like a Red Sox fan rooting for the Yankees.

fietsbob

So, That is the job you are not doing, while you are distracted by this thread ?

Homebrew01

Mavic ZAP was the first electronic group, afaik.

Lakerat

"...and how to figure in needed over shift and fadeback motions"

Road Fan- Do you know for sure that electronic mechs are programmed to do these complex shifting motions? They must be or you wouldn't have suggested it. That's awesome.

I'm glad that you discussed the types of motors possibly used and that maybe the motors are not steppers with some type of transmission or gearing. Would stepper motors be powerful enough? I know that some drive by wire throttle bodies are powerful enough to injure fingers if somebody presses the accelerator pedal when fingers are in there. They are apparently quite fast acting and powerful.

Road Fan

On electronic throttle bodies you are correct. I first came to Michigan to design one at Ford, and they were frighteningly powerful. Stepper motors can certainly be built with enough torque for a bike derailleur. But torque and power-wise, all the major motor/electrical machine technologies were suitable for a throttle control design. In other words any motor technology could be had in any power output required.

To your question, no I do not know directly that overshift profiles are followed by eshift systems. I assume that they are, based on the following. I know that in some of Frank Berto's old analyses of how derailleurs need to work, when the tooth design was not very "grabby" (my term, not a technical term), the chain needs to be shifted past the point where it runs smoothly on the new sprocket and then the cage pulled back to the smooth-running point after the shift has been completed. This manual overshift was accomplished by the human hand by riders like me who are old enough to have grown up with pre-indexing derailleur shifting. We knew we had to do what was needed to shift those gears smartly on the road, social ride, tour, or race, so overshift was a fact of life. Somewhere, perhaps BF, I also read that overshift is sometimes built in to existing indexed shifters. From this point I conclude, if some kind of controlled overshift is still necessary for mechanical indexed shifting it is most likely still necessary for electronic indexed shifting. And I have high confidence that designers of the control algorithms can handle it, if it is really needed. After that, it's just code, and the software engineers live to make code work, among other things.

So the fact I mentioned it means that I think some method to provide overshift is necessary based on my experience, not that I am certain they are actually made that way. Engineers can get pretty tricky, and somebody may have thought of a way to make a full-range derailleur system that does not need to control overshift. Maybe there is not a necessity, at least not one using overshift.

700

Easy to start with some RC servos for PoC.

scott967

I would think a good bit of effort went into the power budget. Both the instantaneous and overall requirement and the battery storage to supply that power. In the case of SRAM I wonder how much existing wireless comm technology was used or adapted.

scott s.
.

Metieval

I don't think cyclist (most of them) have a clue the power it takes to control much more complex systems than a bicycle derailleurs. Not the way they are used in the RC world.

8 servos !!!

Marcus_Ti

Etap, Di2 and Campag EPS does overshift. Di2/EPS also has auto FD trim adjustment for the FD WRT where you are on the cassette. eTap does not have auto FD trim AFAIK. Of all of them...Di2 is the best documented by the general public and most common, the others are simply inhibited by exclusivity/cost. Di2 for example has 32 indexing adjustment stops at 0.1mm apart for the RD, and some FDs have similar adjustment as well as the auto-trim.

https://carltonbale.com/shimano-di2-...-need-to-know/

In general...all these companies do a fairly bad job at making documentation about all this stuff. For eyars Carlton Bale's page has been the consumer bible about all things Di2--due to how bad Shimano was at consumer documentation. Di2, for its part (and the on e-shifting system I'm fluent in) is very cleverly engineered in all it does, not only in precision but in power management.

ogmtb

This is correct. eTap does not have auto FD trim because it is not needed due to the SRAM FD design.

"The final position of the eTap Yaw front derailleur will allow access to all of the rear cogs with no chain rub; it therefore doesn’t require a trim function, meaning that once a front shift is fully completed, the front derailleur will stay in exactly the same spot regardless of the rear cog you select following the completion of your front shift."

Darth Lefty 

spinnaker

Make one for us. Should not take you more than a couple of weeks from the sound of it.

Darth Lefty 

Well you need a Shimergo article and a Basic Stamp or whatever the modern equivalent is. Then you wind up with a project box attached to your bike, which is sub-optimal. You need something that can stand 20 years of use and keep out the weather and look good and be made for a profit. That's hard.

spinnaker

That is only he start of it. You have no idea what all is involved. You need to select materials that will withstand all types of temperatures Know the properties of the materials selected. You need to understand power consumption of your device. Then need to pick a stepper motor that is not over powered or under powered. Then you need to fabricate all of the needed bits and pieces. There are probably several other things I am not thinking of.

Could a clever person envision how sucha a product would be designed? Of course. I am not that clever and I have some ideas of how this would be built. Could a clever person actauylly build the thing and have it work reliably? Likely not. At least not without vast resources.

GrainBrain

That's what I've read as well, surprised no one else has mentioned it?

It's unique in that it didn't use a servo motor, instead relying on a solenoid and the cassette/chain to physically move the derailleur.

I suspect the seemingly slow advent of e shifting is from need, and not technology limitations. A bike transmission is dead simple, and cable actuation is dirt cheap. Of course as technology progresses prices come down.

What I think would be cool? Electronic shifting paired with a power meter and cadence meter, so that shifts could always be at the perfect point in your pedal stroke, and the derailleur could adjust the force required for silent shifts under full power. Maybe this is a bad idea, as we all have a certain amount of pride in a well executed shift while under power as we pass someone

spinnaker

It is a solution looking for a problem. Who wants to go for a ride and risk losing charge on a battery?

My Aurora has both index shifting and friction shift. The reason? In case index shifting fails. You arre getting that in electronic shifting.

The only advantage that I see to electronic shifting is that you could have individual settings between gears. But with ta properly designed/installed/maintained shifter/cassette, I don't see where it would really be needed.

Homebrew01

I think that already exists. I remember seeing a review of "automatic" electronic shirting.

Wouldn't interest me. I like deciding when to shift, and choosing my cadence based on how I feel that day.

Marcus_Ti

Zap meet an end because it was before it's time. The device communication wasn't encrypted and neat things happened with shifting around power lines... Neat as in inconvenient

We take for granted how well things can work... When the reality is that they are frightfully complex and can come apart.

Ironfish653

French Engineers; always reaching for the stars, God bless 'em.

Ironfish653

I think @darth_Lefty does have some Idea. As he and others have said, derailleurs are pretty straightforward in their operation. It wouldn't take much to use a servo/stepper to provide actuation of the mechanism. Even providing a push-button control of the shift map isn't a big stretch for someone who's dabbled in RC or automation. I probably have the components in my garage to build such a basic system right now.

Could I build a fully-integrated Di2? Heck no, getting everything shrunk down and integrated is what the OEM's do.