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Bike intervals - how steady can you hold power?
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I'm still somewhat new to a power meter and I'm using the WKO optimized intervals. Here is my workout:
  • 5 intervals
  • 3:38 long with equal rest.
  • The target range is 109%-119% of FTP
  • At my pitiful FTP, that is about a 20 watt range
  • I'm using a Forerunner with Garmin Vector 3 power meter and looking at the metric Power 3s.
  • I'm doing this workout outside on smooth, flat, concrete roads.

The problem I have is I'll be just a little below the range so I'll add just a little more power. Somehow I instantly swing to way too much power. So I try to back off just a little, and it instantly falls way below the range. Repeat non-stop until the interval is over.

Is this just normal for power ranges above FTP or do I just lack some skill?

I realize wind can make it tricky but I seem to have the same problem even when it is fairly still. Maybe I'm just underestimating variable outdoor conditions?
Last edited by: tomljones3: Jul 19, 19 12:37
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Re: Bike intervals - how steady can you hold power? [tomljones3] [ In reply to ]
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Is this on a trainer or outside, and if on a trainer, what trainer. This probably depends a lot on environment.

I had a Kurt Kinetic Road Machine-- one of the smoothest dumb trainers on the planet-- and I could probably keep my power targets within 5W at near-FTP. Outside is harder, because there are way more environmental factors at play. Now that I have a smart trainer, it is kind of out of my direct control. Still, on that one, I think my power fluctuates as much as ±10W at times, but it is probably typically ±7W.
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Re: Bike intervals - how steady can you hold power? [exxxviii] [ In reply to ]
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Good points, I should have included that info. I edited my original post.

Maybe I'm just underestimating how variable it is to ride outside?
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Re: Bike intervals - how steady can you hold power? [tomljones3] [ In reply to ]
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It has been a super long time since I have done intervals outside, but I bet I swing at least ±20W over a longer interval. Little road undulations, small turns on the road, impact of fatigue at the end of the interval, etc. all cause swing. Now, when I a riding a TT at race effort, I bet my power swing is well under ±10W and maybe as good as ±5W.
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Re: Bike intervals - how steady can you hold power? [tomljones3] [ In reply to ]
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I would do that workout indoors. If my FTP is estimated correctly I'm pretty much destroyed by the end of that set... I just can't imagine doing this outdoors safely.

What's your CdA?
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Re: Bike intervals - how steady can you hold power? [tomljones3] [ In reply to ]
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Don't worry about the wattage at that moment. It's about the average power of the interval not every second's power.

You want your intervals to be in that range. You don't have to be spot on 222w if that's the target. Ride them in the 220-230 or 215-225 range & you'll be fine.

The shorter the interval the more variable the power. The longer the interval the smoother your power application will be. The flatter the road or even better if it's a 1-2% false flat the more level your power will be. The more dips, small hills, short climbs/descents the more variable your power will be.

Hope that helps

.

Brian Stover USAT LII
Accelerate3 Coaching
Insta

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Re: Bike intervals - how steady can you hold power? [tomljones3] [ In reply to ]
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Use the 10sec averaging function.

"Good genes are not a requirement, just the obsession to beat ones brains out daily"...the Griz
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Re: Bike intervals - how steady can you hold power? [stringcheese] [ In reply to ]
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stringcheese wrote:
Use the 10sec averaging function.
It actually might be better to do the opposite, and use a very short averaging. People who overshoot with their power ramping often do so because the number the see on the display takes too long to respond to their changing power. By the time the number on screen gets to the desired value, the rider has already overshot it by quite a bit. The solution isn't a smoother display, but a more responsive display.
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Re: Bike intervals - how steady can you hold power? [tomljones3] [ In reply to ]
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I use 3s avg power to display on my computer, along with the lap average.

If I'm doing a 4' interval at 110-120% outdoors, then at any given moment, my 3s avg may be 100-130%, but for the most part it is in the 110-120% range. Don't worry about this too much. More importantly, once I settle in for the first 30 seconds or so, my avg lap power pretty much just sits on target. So if my target is 265 watts (between 250-275) for a given interval, once my lap average gets there 30 seconds into the interval, the lap average will never really fluctuate more than 262-268.

If you're doing a 4' interval, and after 30 seconds your lap average is 250, but after 90 seconds it's 280, then at the end of 4 minutes it's back down to 265...then that would be an example of not holding steady power.
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Re: Bike intervals - how steady can you hold power? [HTupolev] [ In reply to ]
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I also use a short average for my displays power and my power traces indoors are spot on. Outdoors is a different story though since there is nothing flat around here, even the climbs have many grade changes. This got much better when i switched from 5s to 2s avg power.
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Re: Bike intervals - how steady can you hold power? [tomljones3] [ In reply to ]
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Yep, it's going to be tough to hold a power range on open road. Soooooo many variables. You can do your best, but precision is gained best on trainers.

But, riding outside is the best training since usually you race outdoors... unless you signed up for NYC tri... too soon?

Ryan
http://www.SetThePaceTriathlon.com
http://www.TriathlonTrainingDaddy.com
I got plans - https://www.trainingpeaks.com/...dotcom#trainingplans
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Re: Bike intervals - how steady can you hold power? [Jason N] [ In reply to ]
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Using 3s Power and AVG lap power at the same time sounds like a great solution. I'll give that a try tomorrow.

>> I would do that workout indoors. If my FTP is estimated correctly I'm pretty much destroyed by the end of that set...

But if I did the workout indoors I would miss the fun "cool down" which really means trying to wobble home under 40 watts of power :)

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Re: Bike intervals - how steady can you hold power? [tomljones3] [ In reply to ]
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Pedal speed can cause some big swings.

It's harder to get big swings at higher pedal rates.
If I am below 80 rpm adding or losing a couple of RPM's can cause significant changes.
Just a thought.
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Re: Bike intervals - how steady can you hold power? [tomljones3] [ In reply to ]
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I only started to use power a couple of years ago. It is a totally different style of riding. You say that you spike yourself at the start of the interval then back off and power drops massively. I have found starting the interval in an easy gear and building to your desired power-stay there until you get to a slightly fast cadence then switch one gear and repeat this process until you are where you need to sit (power) for the interval. This may take a few gears and some time but you are always on your number.
Its kind of like if you are on rolling terrain doing an interval to maintain steady power you are going slowly up the hill but then hammering downhill to try and maintain power.

on up and down terrain the goal is to try to have your power look even like

220-180-220-180-220-180 = average 200W

Not like

350-50-350-50-350-50 = average 200W

In a race situation every time you spike you power (heart rate) you are burning matches that you will want to save for later in the race.
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Re: Bike intervals - how steady can you hold power? [kanman] [ In reply to ]
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Living in Melbourne, I am a big user of the smart trainer due to weather/safety constraints. As has been mentioned here, it can make you extremely strong across a range of intervals with minimal variability. However, I have found anecdotally that relying on doing efforts on the trainer all the time has impacted my ability to perform in more variable environments (i.e. outside). There is a different interplay of energy systems through a 3min effort where you might go out at 400, drift back to 350 then finish at 410 then say a 3min interval on erg mode at 370. That is not to say both don't have a place, more so just to respect that there is a difference. As such, instead of having athletes try to stay in an extremely narrow power range through the entirety of an interval on the road (which can actually be dangerous too), I would use the outdoor opportunities knowing that it will be slightly different to the indoor efforts. IMO, I think the ability to ride to the inherent changing conditions of the great outdoors is best executed by Cam Wurf. Seemingly, his ability to know when to use his 'matches' is pretty much unmatched when he's on form on the bike.

Coach at Scientific Triathlon
http://www.scientifictriathlon.com
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Re: Bike intervals - how steady can you hold power? [ljkerin] [ In reply to ]
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Thanks for all the help. Here is what I learned over the weekend:
  • I put 3s Power as one data point with Avg Lap Power right next to it, this was a big help.
  • I eased into the interval, creeping up on the desired power range and this was a big help also.
  • Once I got to the power range I made sure my cadence was up around 90 and this was a big help also.

Finally, I learned that I can't do 2 run interval sessions and 2 bike interval sessions in the same week. :(
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Re: Bike intervals - how steady can you hold power? [desert dude] [ In reply to ]
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desert dude wrote:
Don't worry about the wattage at that moment. It's about the average power of the interval not every second's power.
.

This !!! ^^^^^^

After very little practice you should be able to pace these intervals well enough without looking at the PM. That doesn't mean you'll hold "steady power"... but that doesn't matter. The important thing is to get the effort in the general range, and the AP about the same for the whole set.
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