Certainly not pointless. It's like going for a run without a watch. Still a physically straining effort.

Just base the 20 minute efforts off feel. By the end of it you should think, "That kind of sucked... A lot. But I'll be ready to do it again tomorrow."

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Alex Arman

Strava

2x20 intervals are more than long enough that you can do OK measuring effort using heart rate. And, it would not be pointless to try without a power meter.

But, have you tried TrainerRoad and virtual power on the trainer? It's almost as good as having a real power meter and only $10 a month plus a very minimal investment in hardware (under $100 if you already have a computer or laptop).

If the OP is only focused on 2x20', he doesn't even need TR. All he needs to do is find the speed that corresponds to the effort he wants to hold, then just hold that speed as best as possible. Just like TR, tire pressure and rear wheel tension consistency is important.

Having the actual TR software becomes a little more convenient when you're doing a workout with a lot of variation.

Best workout....ever.

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"Base training is bull shit" - desertdude

what, bike workout with no PM? Thats like swimming without a power meter, or running without one.

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some days you're the windshield some days the bug

That's all you need to know.

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What are you people, on dope?

—Mr. Hand

Before power meters people used rear wheel speed sensors, constant tire pressure, roll down tests on their turbos. Do some kind of FTP test (go as hard as you can for 20-30mins, and note average speed, and derive FTP speed as a %) and use the resultant speed to guide effort on intervals.

SteveMc

If you find out the slope & intercept for your trainer you can use some Maths to figure out the power at a given speed, which is what trainer road is doing but real time.

power (w) = slope x speed (km/h) + intercept

Do your FTP test work out the power and then work out the speed you'll need to go for what ever power ranges you're working to.

You can do it by speed, however my Cycleops Jet Fluid Pro decreases the Power/Speed ratio with time.

In a room heated to 19 C:

After a 10 minute warm-up I start my 2x20:00

1 minute into the first 20:00 set, Power is 228w, speed is 28.5km/h
1 minute into the second 20:00 set, Power is 228w, speed is 29.3
1 minute before I finish my second 20:00 set, Power is 228w, speed is 31.5km/h

It would be quite difficult to get the workout precise without a PM.

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My Blog

Just don't do it by RPE. Your legs are an unreliable estimation of power output, especially after 15 or 20 mins.

I was riding (on my PM-equipped bike) alongside (not drafting) a friend who "discovered" intervals. "Let's go ride 10 minute intervals!" OK, let's. I said: you ride, I'll pace you. He rode entirely by RPE, and his ending power was literally 40W less than his starting (by using my power as a proxy). I'm not saying it wasn't hard, or valuable. Just saying that it's not the best way to get out of the workout *what you could get out of it* if you used another method. The constant-speed method would be much better, all other things being equal (like flat road, winds, etc.)

there's a lot of truth in this. For the 2x20, you cheat yourself when you dip into the anaerobic system, which is easy to do, especially in the early part or going up hills. Heartrate is an OK proxy for the long intervals, it takes almost 5 minutes to stabilize from the start though

there's a lot of truth in this. For the 2x20, you cheat yourself when you dip into the anaerobic system, which is easy to do, especially in the early part or going up hills. Heartrate is an OK proxy for the long intervals, it takes almost 5 minutes to stabilize from the start though

There's no question that using a PM or HRM to figure out where things are, and how hard is hard etc . . is helpful. This is particularly the case with people new to endurance sports. They really have no idea of what is hard and what is easy.

However, there is also great value, after a time, in using RPE, to find that edge, and surf along it, knowing by feel, sensation and your bodies own feedback, what it's like.

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Steve Fleck @stevefleck | Blog

Or a watch and a 10 mi stretch of flat road through some Indiana corn fields.

i did all the best racing of my life without power, often without speed or HR of even a digital watch. Just youth.

My Jet Fluid Pro remains within 5W for hour long sets, once you pass the initial 15 minutes or so of warmup: For the same cadence, same gear, at the start and end of a 20m FTP test I'm still doing the same watts.

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ZONE3 - We Last Longer

A cheap wind trainer, provided you ensure tyre pressure and contact pressure of tyre on roller are constant will give you more reliable results than any fancy trainer.

It might be noisier though.

I guess all those previous Kona winners, hour record holders, TDF winners, and countless cyclists who never used Power Meters just really did not know how to train?