Burst intervals on Kickr Snap

trainer

#1

I’ve been dreading doing Spanish Needle for…basically forever, but it was on my calendar for today. I wasn’t sure how well it was going to work because I have a Kickr Snap, which has its own set of nuances that make fast changes difficult (it doesn’t respond immediately).

Just as I expected, Spanish Needle was basically impossible, but not really for the reasons I anticipated. The response time was much faster than I expected, but the biggest issue came during the recovery sections—since there’s a floor to how low the power can go with the Snap given a certain cadence and gearing, there’s no way I was getting down to 40% FTP. I feel like that 15 seconds of recovery is crucial to finishing this workout (I made it through two intervals before I had to call it quits), and the lowest I could get was more like 70% FTP. That’s a pretty big difference.

Curious to hear how others with a Snap (or any other wheel-on trainer) handle this type of workout because I have several workouts coming up with some type of microbursts involved. This will be my last season with the Snap as it were—it’s a great little trainer, but things like this make me realize it’s time to move on to a direct drive trainer.


#2

What wattage numbers are we talking about for the peaks and valleys?


#3

Usually on rides of that type I can do it by finding a suitable gear on the cassette and swapping between chain rings for the peak and valley.

I checked and I haven’t done that particular one but the principle should hold. You may also need to shift on the cassette too.

It also looks like a workout you might consider doing in slope/resistance mode rather than erg.


#4

I ride 1x, so I only have a 50t chainring. :confused:

Makes this particular situation even more challenging.


#5

300 watt peak, 80 watt valley. FTP is 200.


#6

So, for the valleys your target power was 80, but you were hitting 140 instead. I have a Kickr Snap too and the last time I did Spanish Needle, this was my ride file.

In the valleys the trainer was able to get down to 100 or so. This would likely have been in a 39x21 gearing. I see that you’re using 1X, so there may not be much you can do to adjust your wattage floor (assuming you’re running your easiest gears already 50x42 I would guess).

My wife has a similar issue to you at a larger scale. Her FTP is 120, so due to the wattage floor, all her rides are basically the same. She’s yet to find out what a recovery valley is! :smile:


#7

My recommendation is to turn off ERG mode for anything less than 30 secs as I find that my Kickr snap takes about 15 seconds to adjust to a new power target in ERG mode, although this may just be my setup.

Right now, I have my Kickr snap controlled by my stages power meter in the Wahoo app and I have power match disabled in the TrainerRoad app. But, with this setup, it takes about 15 seconds for the system to adjust to a new power target with too much resistance during this time. I am going to try flipping it with power match enabled in TrainerRoad and disabled in the Wahoo app.


#8

I have the same setup, Stages in Powermatch with Kickr Snap, you can see my Spanish Needle ride file above. I get wattage adjustments much faster than 15 secs. What gearing are you running? You may be able to mitigate a lot of the lag from high wattage differential by lowering your inertia on the trainer.


#9

Yes. Very challenging.

All I can say is very fast gear shifts up several gears and do the workout in slope/resistance mode.


#10

@brenph I don’t see that making a difference. In ERG mode, the trainer knows that 140 is being dealt out and it’s trying to get down to 80, so it’s letting off all the resistance it can. A wattage floor is the same for ERG or Resistance modes.


#11

@julianoliver - Good tip! I am running big chainring on front and middle cog on back. If I drop to lower chainring that should take away a lot of the inertia and should help with resistance changes.


#12

Yes, try small chain ring and high on the cassette and see how that changes things for you. Most people report that dishing out high wattage intervals feels more difficult, but the trainer is more responsive to wattage changes overall.

The other thing to do your best with is keeping a consistent cadence through the wattage change. In ERG mode the trainer is trying to constantly match the target power, and fluctuations in cadence is another variable the trainer has to overcome.


#13

My trainer wheel has an 11-28 cassette, and I generally run in the middle somewhere. I’ll try moving up the cassette the next time I have burst intervals and see how that works. Trying to find the right balance where I’m still ahead of the pedalstroke on the hard intervals but still in a low enough gear to hit the “recovery” valleys properly is difficult.

Also, tell your wife I send my condolences and that she’s a bigger badass that most of us—I can’t imagine some of these workouts without a good recovery section!