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2x20 without a power meter
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b33r
Apr 25, 12 12:43
Post #1 of 46
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2x20 without a power meter
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From what I've read/learned on Slowtwitch, the 2x20' trainer workout is
the
thing to do to get fast on the bike. I don't have a power meter - is there an effective way to simulate the workout based on how tired I am? I'm keeping everything as constant as possible (tire pressure, trainer resistance, and tension against the rear wheel), but without a power meter I really don't know if I'm going hard enough or too hard. I did it last night (10 min warmup, 20 minutes hard, 5 minutes easy, 20 minutes hard, 5 minute cooldown), but I definitely didn't feel like I left it all out there. How am I supposed to feel after this workout?
rahciao
Apr 25, 12 12:47
Post #2 of 46
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Re: 2x20 without a power meter [b33r]
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Like you REALLY don't want to do that again for a while. You want to pace yourself so you can get through both intervals, but so that by the end of the second interval you have left it all out there. With the way you sound, there's no way you went hard enough. On the bright side, though, you should be able to recover faster and try again sooner!
marcag
Apr 25, 12 12:51
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Re: 2x20 without a power meter [b33r]
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Do you have a heart rate monitor ? Get to LTHR within say 5 min and hold it for another 15.
jbank
Apr 25, 12 13:02
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Re: 2x20 without a power meter [b33r]
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You could try something like TrainerRoad, or simply manually do what they do, which is to
try to map trainer speed to power. Assuming you are a bit careful about how you setup your
bike on the trainer (same tire, same pressure, same number of turns of trainer knob that sets
pressure against tire, etc), you can record your avg speed for the interval and use that. For
example, try 20 minutes at 20 mph one day. If that is too easy, try 20.5 mph, etc. Good luck.
Borden
Apr 25, 12 13:04
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Re: 2x20 without a power meter [b33r]
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You need to do a 40 minute all out effort and record your average heart rate. You need an easy to moderate 10-20 minute warmup, start the clock and watch your HR dial up. Try not to let it go back down. don't start to hard. You'll be tapering off at the end if you do.
Take the 40 min avg HR as your 2x20' goal HR. Tada!
The good thing is that after a few cycles and tests, your avg HR will stop changing and you don't really need to test anymore. You just keep plugging away at the workouts and hit those HR numbers and get stronger.
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silentcs42
Apr 25, 12 13:20
Post #6 of 46
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Re: 2x20 without a power meter [b33r]
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It seems like there are a lot of approaches to this workout, I do it as close to FTP as I can that day. TrainerRoad is awesome, I must say, and could be helpful to getting you some metrics to go by.
If you're just going RPE, the last 10min of rep 2 should suck. Your breathing should be heavy, but controlled. That "you may want to quit, but you don't have to" feeling. I'm not ever completely wrecked after the 2x20 - tired yes, but unable to pedal anymore, no. In theory I should be able to crank out 20 more minutes, and if you're doing it at 95% (I think that's on the Flanagan link) you should be OK when you're done.
Now the 1x20 @ 105% is a whole different beast...
b33r
Apr 25, 12 13:29
Post #7 of 46
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Re: 2x20 without a power meter [silentcs42]
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I think I'm getting conflicting advice. Some people have said (both in this thread and in previous threads) that you're supposed to feel like you can't go any longer than the second 20-minute session. Others are saying that you should feel very tired, but not necessarily completely out of energy. Maybe this just goes back to the debate over what percentage of FTP you're supposed to ride at during the 2x20? I've heard anywhere from 80-105%.
jstonebarger
Apr 25, 12 13:40
Post #8 of 46
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Re: 2x20 without a power meter [b33r]
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As hard as you can and still complete the work interval. That takes practice.
fartleker
Apr 25, 12 13:43
Post #9 of 46
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Re: 2x20 without a power meter [b33r]
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My opinion is that there are very few workouts where you should feel like you cannot take another step or pedal any more. The 2x20 is definitely NOT one of them. It's a tough workout, yes, but you should feel like you can do another 5+ minutes if needed.
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endorphin
Apr 25, 12 14:07
Post #10 of 46
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Re: 2x20 without a power meter [b33r]
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I also don't have a power meter and I've been doing 2x20 all winter. A reasonable (read: poor man's) alternative to power is use speed. I move my sensor from my fork to the seat stay. Provided you keep all factors constant (tension, tire pressure, temperature = big factor), this is a pretty consistent indicator of power. After a couple sessions, you'll get a sense of what speed corresponds to your FTP.
One thing to note is that power is not a linear function of speed. I believe that most trainers have cubic power curves. So the effort to go from 30 to 31km/h is far less than the effort to go from 31 to 32km/h. Kurt Kinetic sells a computer that converts speed to power based on a preset resistance curve, but I don't see why this is necessary. Speed is much better as a relative indicator than an absolute indicator of power. There's even a lot of resistance variation between trainers of the same model.
On days were I'm fresh, 2x20 @ FTP doesn't destroy me. If I'm fatigued, it can be a really brutal workout. The effort level varies a lot for me.
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silentcs42
Apr 25, 12 14:07
Post #11 of 46
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Re: 2x20 without a power meter [b33r]
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http://forum.slowtwitch.com/...post=3792330#3792330
This post has Flanagan saying that it should be done at 95% FTP. Like I said, there seem to be flavors of this, but if you're truly operating at FTP you should have 1x60 min of effort in you. Now, at the end of that 60 min you should be totally wrecked. Hence, 2x20min @ FTP should be hard but not completely wipe you out.
cmscat50
Apr 25, 12 14:27
Post #12 of 46
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Re: 2x20 without a power meter [b33r]
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I like using trainerroad.com.
I already have my ANT computer on my bike so needed to purchase a garmin ANT stick and the $10 / month subscription to trainerroad. As long as you setup the trainer in a consistent manner as stated above this works fantastic.
I've done a few 2 x 20's on the trainer and they aren't fun. At all.
If you have none of the parts listed above you can probably acquire it all including the subscription for under $150. Still way way less than a powermeter.
Now that I know a virtual (trainerroad) FTP I know my virtual FTP heart rate. Now I can take that on the road and do workouts with a HR monitor. I can also for example take 80% of my FTP virtual watts and get a HR reading at that wattage and take it on the road. So now I have a real close half iron HR to use for races. Very slick IMO.
tburke
Apr 25, 12 14:51
Post #13 of 46
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Re: 2x20 without a power meter [endorphin]
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To the constants I added having the resistance roller always contacting the wheel at the same point if the wheel is taken out & put back in the trainer. No wheel is perfectly round & it does make a difference. I have a old mag trainer with resistance set approx = to road speeds. The resistance is linear, but it does get much more difficult as speed increases. A fan is a necessity. I allow at least 2 days between intense sessions (age 72) for best results at roughly 20K TT effort. At age 60 it was a day or so between.
lightheir
Apr 25, 12 15:02
Post #14 of 46
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Re: 2x20 without a power meter [b33r]
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b33r wrote:
From what I've read/learned on Slowtwitch, the 2x20' trainer workout is
the
thing to do to get fast on the bike. I don't have a power meter - is there an effective way to simulate the workout based on how tired I am? I'm keeping everything as constant as possible (tire pressure, trainer resistance, and tension against the rear wheel), but without a power meter I really don't know if I'm going hard enough or too hard. I did it last night (10 min warmup, 20 minutes hard, 5 minutes easy, 20 minutes hard, 5 minute cooldown), but I definitely didn't feel like I left it all out there. How am I supposed to feel after this workout?
You likely do have a poor mans powermeter - use your avg speed for 20 mins and can convert to power if desired using equations, but honestly the speed number is good enough.
I def cant go 5 min more after this. Maybe 1-2 min more but thats it.
endorphin
Apr 25, 12 15:05
Post #15 of 46
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Re: 2x20 without a power meter [tburke]
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That's a good point that has never occurred to me.
At age 72, I'd say you're doing pretty well with 2 days between hard sessions. I'm exactly half a century younger than you and I sometimes need 2 days between hard sessions.
x2 on the importance of fans. A few days ago I was having a wretched workout until I realized that the fan was slightly misaligned. I centered the air stream on my body and my workout improved noticeably.
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gluestick
Apr 25, 12 15:15
Post #16 of 46
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Re: 2x20 without a power meter [endorphin]
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My n=1 experience. I have have been using a similar protocol as mentioned above, setting tire pressure consistently and consistently setting the pressure of the trainer resistance on the wheel the same every ride. Despite (or perhaps to the benefit of) the before mentioned discrepancies in the cyclops trainer at various temperatures, I have been using it effectively to raise "FTP" during my season's build period.
I am using speed, rather than gearing or cadence, to measure "FTP". I do a 20' all out TT on the trainer, and multiply my avg speed for that period by .95 to get my generalized 60' "speed FTP". I have then been using this speed, and various %'s over and under this "FTP" # (again, using the same PSI and tension setting against my rear wheel) to duplicate power based workouts. No doubt the resistance is there. Last 5' of first 20' set is tough. 3 minute rest in between. Half way through the second 20' set, I get paranoid that the clock is somehow running backwards and can't stop staring at the time, wishing it to go faster. Pretty happy to get off when it's over.
Results: in the past 3 months I have gained nearly 10% improvement on avg speed for this 20' interval. I am undoubtedly coming into this season stronger, faster, and measurably fitter on the bike. A preseason well spent. Another gratifying thing to note, a saddle is far more comfortable for 2.5+ hours on the road than 1 hour on the trainer.
While I have no doubt a powertap will make this more of a pure science and I am still simply lurking in the shadows of truly understanding precise training, my "poor man's powertap" is going to be paying dividends this season, without a doubt. I still have every intent of one day getting a PT, as I can imagine the pacing guidance and true balls on accuracy of training zones will prove valuable, but in the mean time, I am making the most of my time on the trainer for no more than the cost of a cateye strada.
Shut up body and do what I tell you.
-Jens Voigt
Jamaican
Apr 25, 12 15:24
Post #17 of 46
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Re: 2x20 without a power meter [b33r]
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If you have rollers you can use speed as a good measuring stick. Without the wind resistance component P & V are proportional at constant speeds. Not to be confused with outdoor riding speeds though.
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endorphin
Apr 25, 12 15:29
Post #18 of 46
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Re: 2x20 without a power meter [gluestick]
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That's a great improvement. There is one small flaw with your calculation. As I mentioned before, on fluid and wind trainers (and probably a lot of mag trainers) power is a non-linear function of speed. It's usually cubic to replicate real riding conditions where power to overcome drag is proportional to v^3. By multiplying your 20 minute test avg speed by some factor to calculate your FTP and other zones, you are implicitly assuming a linear relationship. In other words, a 5% difference in speed is definitely not equal to a 5% difference in power on most trainers. I doubt it's a big difference though. Short of collecting data points with a power meter and fitting a curve to your specific trainer, there's really no other way besides guessing.
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(This post was
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Nate Pearson
Apr 25, 12 15:33
Post #19 of 46
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Re: 2x20 without a power meter [b33r]
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b33r wrote:
I think I'm getting conflicting advice. Some people have said (both in this thread and in previous threads) that you're supposed to feel like you can't go any longer than the second 20-minute session. Others are saying that you should feel very tired, but not necessarily completely out of energy. Maybe this just goes back to the debate over what percentage of FTP you're supposed to ride at during the 2x20? I've heard anywhere from 80-105%.
When I do these I go as close to 105% as I can get. I look at the average from my first interval and try to beat it for my second interval. If I can hit the same power on both intervals, I bump it up 5 watts next time.
Just repeat this over and over and you'll get really strong. Throw in some VO2 work when you get in season and close to a race. Works like magic :).
And yes, you can do good 2x20 intervals on a trainer. What trainer do you have though? Some get easier as they heat up; some are rock solid though.
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gluestick
Apr 25, 12 15:50
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Re: 2x20 without a power meter [endorphin]
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endorphin wrote:
That's a great improvement. There is one small flaw with your calculation. As I mentioned before, on fluid and wind trainers (and probably a lot of mag trainers) power is a non-linear function of speed. It's usually cubic to replicate real riding conditions where drag is proportional to v^3. By multiplying your 20 minute test avg speed by some factor to calculate your FTP and other zones, you are implicitly assuming a linear relationship. In other words, a 5% difference in speed is definitely not equal to a 5% difference in power on most trainers. I doubt it's a big difference though. Short of collecting data points with a power meter and fitting a curve to your specific trainer, there's really no other way besides guessing.
Agreed. I suppose if anything, I am working slightly harder than I think I am, which is OK by me.
The 2x20 is certainly the key, though. It's pretty gratifying after my first off season of this structured protocol to go outside this spring and realize my new cycling potential. I wish there was some way I could go back in time and race the cycling me of last year at this time, and smoke him! It makes me want to do more and more work on the trainer!
Shut up body and do what I tell you.
-Jens Voigt
b33r
Apr 25, 12 16:02
Post #21 of 46
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Re: 2x20 without a power meter [Nate Pearson]
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I have the
Blackburn Tech Mag 6
. I wasn't aware that some trainers get easier as they heat up.
Also, I heard of TrainerRoad today and just ordered an Ant+ cadence/speed sensor for my bike - I'm hoping the ~$40 purchase (plus the monthly subscription) can give me a decent approximation of my actual wattage.
beebs
Apr 25, 12 23:28
Post #22 of 46
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Re: 2x20 without a power meter [b33r]
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I have had a powermeter long enough to know what ftp feels like. Now that I'm riding outside sometimes on hilly routes, I don't keep a close eye on my powermeter because the numbers will be moving up and down depending on winds, hills, turns, gear-shifts, out of saddle efforts, and bumps. I now treat the 2x20s outside as two time-trial efforts, and then I check my AP and NP when I get home.The numbers are usually right around where I want them to be. The first and last 5 minutes of the first 20 minute effort usually sucks... Then the 5-15 minutes of the second one sucks, but the last 5 are usually whatever I have left to just keep going. After about 5-10 minutes, I'm able to ride harder again and stay in tempo or the lower end of sweetspot. I don't think I could have done that when my cycling fitness wasn't as good as it is now, so your mileage may vary on how wasted you feel afterwards. A ride I like now is a 2 hour ride with the 2x20s starting about 40 minutes in and a steady tempo effort after to bring myself back home.
So, cliffnotes: Ride two 20 minute time trial efforts, and I bet you'll see improvement. The big difference is you won't be able to track improvements as well without the powermeter, and you won't know if you're pacing well (but after enough intervals, you will figure it out powermeter or not).
Rambler
Apr 26, 12 6:51
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Re: 2x20 without a power meter [b33r]
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I don't have a power meter because I don't really care about numbers. When do the workout the 1st 20 isn't too bad. The back 1/2 of the second really sucks. Trial and error until you find a steady effort that gets you there.
tburke
Apr 26, 12 7:12
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Re: 2x20 without a power meter [endorphin]
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My hard sessions are shorter than they used to be, & I normally stick a recovery session/ride in between. I also do 1 min on, off, 3 on, 2 off, both at higher speeds than 2x20. For a week it's usually 2 intense, 1-2 recov. Depends on rest of my life. Variety is good.
sub-3-dad
Apr 26, 12 7:36
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Re: 2x20 without a power meter [endorphin]
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endorphin wrote:
I also don't have a power meter and I've been doing 2x20 all winter. A reasonable (read: poor man's) alternative to power is use speed. I move my sensor from my fork to the seat stay. Provided you keep all factors constant (tension, tire pressure, temperature = big factor),
..
.
Temperature is a big deal with fluid trainers.
I have an Elite Crono Fluid trainer and there is a huge difference in it's resistance accross temperatures.
I find that the viscosity (and power/speed curve) levels off after about 10 minutes of intensity.
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