Question about sprint work in TrainerRoad

For a workouts that include sprinting – like Bays, Andrews +1, Birling, etc. – here’s my question:

I use a Kickr almost exclusively in ERG mode – and when I do any of these workouts, it kicks me up to about 180% - 225% of FTP, and those wattages are roughly between 450 - 550 watts. However, my true all out sprint will peak above 1000 watts, so for those workouts am I really training my sprint? Would the better idea be to do these workouts in resistance mode and just go flat out and not focus on the wattage guides? Or is the software truly trying to limit my sprint output?

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I have read other athletes here choosing resistance mode when a workout requires sprints like those you are referring to and using ERG mode for everything else.

Possibly when its short sharp efforts with minimal rest resistance mode is the better option.

Give it a try and see…you’ll still be getting benefits of the workout

I always do those sprints sitting and in ERG, though I have been wondering if thats the intention. I find it a good challenge anyways and as has been mentioned on the podcast, having a stealth seated sprint/jump can be handy to get a gap.

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I think this may well depend on your particular goals. It seems that TR doesn’t really plan for, or recommend “all out sprints” on the trainer. So I am guessing they are just targeting the upper end Anaerobic zone, not necessarily peak sprint power.

I think you can do whatever makes sense for your needs, with the very particular focus on your effort, body position, bike control and such to prevent injury to yourself or damage to your equipment.


Shameless plug, but a rocker plate might just reduce the risk of damage to your equipment from the increased freedom of motion. Totally unproven at this time, but I firmly believe they can effectively reduce peak loads on the equip.

Save sprinting for outside. A good sprint involves a significant amount neuromuscular adaptions, so I actually think it’s counterproductive to practice a sprint indoors.

I agree with @PVDBG to do them seated

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Not true, bays and mokelumne both instruct you to switch to resistance mode if the sprints are too easy, but to remain seated.

Having never done this… if you switch from ERG-to-resistance-to-ERG again in a workout like Bays – is that switch fairly instantaneous? Do you need to give yourself 30 seconds or so to figure it out?

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First, it’s best to do this on PC or Mac. Switching on the mobile app is a royal pain.

For PC, you can use the ‘M’ key to toggle between modes easily. Or you can use the mouse and click in the ERG location to select mode. This is true for Mac, but it does not work with the ‘M’ key shortcut.

Also, the default for Resistance or Standard modes are 0. So, right after warm-up, I switch modes and set a Resistance to something between 20-30%, or around 3-4 in Standard. When you toggle back to ERG, and then to Res/Std, it will resume the prior setting.

And yes, there is a slight delay at each stage of mode switching. I haven’t timed it, but I would say around 2-5 seconds, depending on the relative difference in resistance settings at the trainer.

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For reference, I’m using a Tacx Vortex. I had Haku last week which has " 6x20-second all-out efforts at 200% FTP, each separated by about 5 minutes of active recovery at 65% of FTP." The sprint efforts are around 600 for me and on the first one my trainer didn’t have even close to enough resistance to hit the number. I got it to about 300 within 2 seconds and it didn’t really get any better and I ended up spinning out. I switched over to resistance (70%) for the rest of the workout and was able to hit every interval with a little extra. Really depends on your trainer, but going forward, all my sprinting will be done in resistance mode. it’s fun to toggle back and forth anyways. Keeps things interesting.

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Another vote for doing sprints outside. But if you are going to do them inside, stay seated.

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+1

I really can’t sprint, especially not on the turbo. My 5 second max power on the turbo is something like 800watts, which is a couple of hundred lower than my 5 second max out on the road. For me, sprinting requires my whole body and the ability to move the bike around. I just accept that if I want to work on full on sprinting then I need to do that outside

As someone who races in a full sus mountain bike, learning how to do a controlled seated sprint/ big surge is really helpful. Getting out of the saddle too long means a lot of wasted energy compressing the fork and shock.

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