Hi folks. ERG mode on my Stages SB20 is noticeably slower to respond than my old Kickr. This is regardless of zwift or trainer road use. I’ve moved excessively to TR now but was curious if there’s anyone who’s figured out a fix for this?
The lagging nature makes doing intervals on the SB20 not so great because I’m either a) in ERG mode and on shorter 15 or 30 second intervals you spend little time at target power. Or b) I’m not in ERG mode (how I normally ride these sessions) and I’m clicking up and down gears a zillion times for all these short punchy intervals.
I’ve played around with various settings and can’t seem to figure it out. I could try to find rides with longer intervals but that means I’m not really following a plan per say. Intervals that are about a minute in length or longer I’ll sometimes use ERG mode since I still get a good amount of time at target power. Anything short of a minute and I’m manually shifting and trying to monitor output. Workouts like Joe Devel and Sleeping Beauty are a PITA.
Hmmmm. Can you provide screenshots showing the lag you are seeing in ERG mode?
Things to try:
Are you on the most current version of the SB20 firmware? If not, update and see if that makes things better
In ERG mode, are you keeping a constant cadence going into these short intervals? If not, try that and see if it makes things better.
For doing intervals in non-ERG mode, I’ve setup my SB20 to use DreamDrive mode for shifting with 50 gears, and I set one set of the buttons to jump ~7 gears higher / lower. That way at the start / end of an interval I can very quickly increase / decrease the “gearing”, and then fine tune by going up / down in single gear increments. I find DreamDrive with 50 gears is the best setup for indoor riding, as it lets you fine tune gearing / cadence. I’m riding indoors to start with, so I don’t care about matching the gearing I have on my road or gravel bikes. Especially as I’m doing a prescribed power workout, and not responding to actual terrain changes / changes in the group power.
I’ve found the same ERG issues with my SB20, so I switched to Dream Drive and just change the gears to adapt to new intervals. Also keeps me paying attention. Suitable for the vast majority of workouts – exceptions where I wish ERG worked better: rapid VO2 sessions (30x30s, 20x20s, etc) and anything with a short ramp (eg, ramp from 250-280W over 30 seconds.),
15-20 second intervals, I’ll switch to resistance mode.
30+ seconds is usually enough time for TR app to hit the average over the interval so I leave it.
ERG mode is just back solving for torque at the given rpm you are at, to give it the right resistance to meet the power target. If you vary your cadence greatly while switching targets, the trainer has to recalculate it multiple times to chase your rpm down.
Fwiw I don’t find it any better or worse than the KICKR core I use on occasion, the only real difference is the Stages reports your actual output, while the KICKR reports the target (or a heavily smoothed output). Next time you ride the KICKR, play closer attention and you’ll feel the resistance changing under you despite the graph showing the same. I prefer to know the actual work I’m putting in.
I just did a custom workout on my SB20 in ERG mode that included 9x30 @115% with 30 seconds recovery @50% between intervals, and this is what it looks like. So I’m not seeing the an issue with lack of responsiveness or anything that leads me to believe you can’t do these types of intervals in ERG mode with the SB20.
My problem is that I can’t tell if the SB20 has shifted, so I’ll click the button again and overshoot. I wish there was a louder sound or some kind of feedback that the shift happened. The delay of the resistance change is what trips me up. First day on the SB20 so maybe I’ll get used to it
I’m not doing that actually, I am bringing the cadence up 10-15 seconds prior to the interval beginning, not right as it starts.
Now sometimes on an interval when it’s going from 130w to 480w, it might drop 2rpm with the initial power requirement change but it’s pretty consistent. I’ve been playing around with changing cadence early, not changing cadence, etc. It’s def faster changing cadence 10-15 seconds ahead of time as you said. But that merely gets me in the 10 second range.
That was sample data to show some of the hesitance/delay. I"ve been playing around with when to lift cadence and how quickly. It’s generally before the interval starts. Generally the drop is 2-3rpm so it’s not very big if there’s a drop. The quickest I’ve been on target is about 8 seconds. Otherwise it’s pretty consistently 12-15 seconds almost irregardless of what I’m doing with cadence. Although I will say if I start off at a lower cadence, say 90rpm and then raise it to 105rpm or so over the course of the first 10 seconds of the interval it takes much longer to get on target.
This what got me thinking originally as you posted, that raising my cadence earlier might fix it. While it gets it down to 10, 12 or 15 seconds, that’s still a long time in the context of a 30 second interval.
For me, ERG seems responsive enough… unless the intervals are super short, like 15-30 seconds. For those, I still leave everything in ERG mode, and just squeeze the brakes at the start and feather them back as the interval progresses.
p.s. this is a whole different subject than whether the SB20 is accurate, precise, or has reasonable pedal feel. (All of which I think suck on the SB20 and generally have me on my Kickr these days)
That’s just the way this thing is. I was hoping Stages would someday fix it, but the previous firmware update I was finally forced into actually made it even slower to hit target and stabilize than before. Now 15 seconds into an interval is pretty typical. In my case below, what tends to happen is it will briefly hit the target, then inexplicably drop a good 30 watts below for a good 8-10 seconds until getting back up to target. This is with a 78-79 rpm cadence.
Following this thread as I just bought an SB20 today as the +zwift deal was too good to pass up. been riding a kickr for the past 3 years. no zwift, just TR almost always in erg mode. the DC rainmaker review spooked me a little. will report back, as I imagine I will have a similar experience.
I also bought the SB20 on the zwift deal and experienced the same. It’s not an issue with power smoothing. I understand the SB20 only looks like it’s jumping around more relative to other trainers, but is actually rock solid. The issue is that in any interval shorter than 15 seconds it simply cannot keep up in erg mode. My average power in each one of these was 5-10w lower than it should have been.
The one that’s all messed up was from me trying to use the brakes to get it to pick up faster. I ended up just switching and completing all remaining sets in resistance mode. Overall, love the bike. This is my main gripe. It’s no good if you spend the first 10 seconds of a 15 second interval at 50% the power you’re supposed to be at.
Will note, I’ve had the SB20 for about two years and don’t have this lag problem at all. Looking at some recent workouts it gets me up to power within 2-3 seconds. Average power on intervals of various lengths is typically +/- 1 watt.
I have noticed changing cadence at the start of the interval will increase the lag time, so I typically get that set 5-10 seconds prior to the start and hold it constant throughout.
I usually do that as well, but perhaps I’ll try backing it up to 5-10 seconds before. If I have to do short intervals in resistance mode it’s not the worst thing in the world. I’d just rather not with such an expensive bike.