20 minute intervals

[leanman]

the all important 20 minute interval.. when doing these on your trainer this fall/winter, is it best to concentrate on
cadence, or using a bigger gear?? my cadence is 108-111 the way i been doing them these past few weeks. if i used a bit bigger gear, the cadence would drop, but my heart rate would be the same.. is the key the heartrate? keep the 20 minutes at 85% of max, weather it be a higher cadence, or lower cadence using a bit bigger gear, maybe going 100 rpm's. thanks

 

[fergie]

Focus on the intensity. Preferably the power you can sustain for the ride but HR if that is not an option.

Over the last two days I did the same ride and saw the following...

Wed: 30min power 197 HR 160
Thu: 30min power 197 HR 167

Yesterdays ride felt a lot harder but the difference in temperature between the two days was around 15 degrees centigrade so heat was a bigger issue. I felt it more but the actual intensity was the same.

Also remember if doing indoors that heat will be a major factor so drinking ice water and using a fan and open windows will help.

 

[daveryanwyoming]

The key is neither HR nor cadence but power. If you don't have a power meter but ride the same trainer (and the same resistance setting if it's an adjustable load trainer) then wheel speed is your most important thing. Ride whatever gears at whatever HR you need to to hold high power(wheel speed) but not so high that you have to back off during the intervals to finish them or have to back off a lot between the first and second efforts.

The idea is your highest 'sustainable' power for the efforts and 'sustainable' applies to each effort individually, the set of two or three, and your overall training block or week as well as your long term plan.

-Dave
[edit] Fergie's example illustrates the issue with HR nicely, power which is the best proxy we have for training stress can be the same but HR can vary a lot due to other things including heat. Cadence tends to impact HR as well with most folks experiencing higher heart rates while sustaining the same power if they ride with higher rpms. As Fergie says, focus on intensity...

 

[leanman]

thank you..
i have no power meter, just a $100.00 trainer stand, but it works fine.
i may do one 20 minute interval at a higher cadenceaiming for my normal 170 bpm heart rate, then my next workout i may do one in a bigger gear with a bit lower cadence, but have the same heart rate. i think my max is 200. i had it up to 194 a few times, doing veruy hard intervals, so i imagine going all out, its a bit higher.. so that 170 i do feels tough and hopefully will be fine.
thanks again

 

[Yojimbo_]

I think you missed the point about power and wheel speed.

Go through these threads again.

 

[zaskar]

Try at 220 next time lol .. jk.. like the others said, go through the millions of 2x20 threads.

 

[Pureshot78]

The only thing I would add to this is that if you have a lower quality trainer, the wattage required to maintain a given speed might change during the course of a workout.
Before I got my first power meter, I trained using wheel speed for a while, and found it difficult to maintain a given speed for a 20 minute interval.

At first I attributed it to lack of fitness, but after I got a Power Tap I noticed that my wheel speed would slowly decrease for a given wattage during a workout.
Now, even though I train by watts not speed, I use a second fan to blow over the cooling fins of my Fluid Trainer.
I prefer to maintain a particular cadence for a whole interval and that helps me be able to do it.

Originally Posted by daveryanwyoming .

The key is neither HR nor cadence but power. If you don't have a power meter but ride the same trainer (and the same resistance setting if it's an adjustable load trainer) then wheel speed is your most important thing.

 

[baker3]

I feel its hard to compare power/HR on the trainer vs on the road. The trainer under states power and over states HR, especially if its hot.