[BUG/FR] Add microshift to virtual shifter

[jwoodford-woody]

I'm not sure if it's a setting or just something in the combination of the C6/SS2K Stepper motor limitations, but one thing that has happened to me is that my bike resistance and my SS2K gear tends to creep after a series of hills/gear shifts. After just 30-45 minutes, I've had the SS2K gear not returning to the same bike resistance I started with. For example, If I start with my bike at 24 resistance and the SS2K in gear 3, I've had to bump it to gear 4/5 by the time I'm that far into my ride just to have it in the 24/25 resistance range again and gear 3 might be down as far as 16-18 resistance on the bike at that point. On some 60+minute rides, I've had to be in 6th gear on the SS2K to get the correct bike resistance I am looking for when on flat roads but even then, it's hard to get back to a preferred range depending on virtual shift settings.

What about something like in the attached image? Ignore the speed shift on the left - that is in another feature request on a separate chain.

I'm thinking it could be something with these options:

• Enable/disable (from settings menu) which would toggle the button visibility on the virtual shifter page for those that don't want/need it.
• Adjustable micro shift motor revolutions (from settings menu) so the user can select the interval (100 steps was just a default thought that came to mind) but I'm not sure the stepper motor specs nor the gearing of the output so 100 may not be the correct default. This value in the settings would update the display on the virtual shifter.
• The micro shift is only there as an on-the-fly correction to the gearing and does not affect the gear homes. So let's say I start with bike setting 24, SS2K 3 and I am 45 minutes in but SS2K 3 is now returning to bike setting 27 instead, The user would bump the micro step up or down to get bike resistance (and thus my RPM/Watt range) back to the expected gear point.

I suspect I'm losing steps somewhere along the way which is causing the discrepancy, but without knowing the full system setup, I'm only speculating.

With it smaller and in the middle of the regular shift buttons, it would be something a user wouldn't accidentally hit.

[doudar]

Micro shifting unfortunately isn't going to be possible, but I kind of like the idea of a +5/-5.

As far as the stepper losing position, this shouldn't happen. I actually just monitored mine last night after 1.5 hours and it didn't lose position.

A few causes I can think of:

1. If your knob is hard to turn, possibly it's losing steps there. You could fix that by increasing the stepper power in settings.
2. If you're riding without an app attached it might be completely powering down the stepper between shifts.
3. The IC4/C6 resistance sensor isn't great - it's just a potentiometer which is affected by temperature and will drift as it warms up or cools down. A standard variation for potentiometers is +-20% . You could determine if this is causing the issue by riding at a set state without the SmartSpin2k for an hour and see if the value changes.
4. If you're riding without homing enabled and it's crashing into end stops, that's a problem - just do a calibration in SmartSpin2k companion app or your workout app to have it find and save the end stops.

[jwoodford-woody]

To address your potential causes:

1. If your knob is hard to turn, possibly it's losing steps there. You could fix that by increasing the stepper power in settings.

My knob is not hard to turn but I had this thought as well. I think I did bump this up already once but I can't remember if I set it back to the default power at this point. What is the default power setting so that I can see if I'm running at that? I don't know how to check without reset all of the settings which I'd prefer to not to.

2. If you're riding without an app attached it might be completely powering down the stepper between shifts.

I'm not positive I know what you mean, but every time I've used the SS2K (aside from initial setup), it's been while connected to Zwift which I think means I am not running without an app as you're suggesting.

3. The IC4/C6 resistance sensor isn't great - it's just a potentiometer which is affected by temperature and will drift as it warms up or cools down. A standard variation for potentiometers is +-20% . You could determine if this is causing the issue by riding at a set state without the SmartSpin2k for an hour and see if the value changes.

I have done several steady state rides and almost never have any creep. The most I have ever seen is if I have the knob right on the edge of a setting and it might flash back and forth so I can just tweak the knob slightly to get it firmly within a number but it stays where set. Definitely a difference between that experience and what I am getting with the SS2K returning after hills/shifting, though. I had a ride last night that it was off by 4 levels within the first 10 minutes which I thought was odd.

4. If you're riding without homing enabled and it's crashing into end stops, that's a problem - just do a calibration in SmartSpin2k companion app or your workout app to have it find and save the end stops.

There may be something to this...my bike, as you know, has virtual stops, not physical so it's not hitting anything. I did an initial calibration with the SS2K app but when I'd opened Zwift, it made me do the little calibration thing at some point so maybe there's something that got off with that. I will recalibrate and see what that does for me.

In the end, I suppose if a speed shift option becomes available and I cannot get the drift to stop, I could also just lower my shift steps even more and then rely on the speed shift to get my resistance up for sprints, etc.