Heart rate v leg strength

I recently rode the Alpe in 74 minutes using a dumb trainer with a manual resistance changer.

In order to get what i thought was the correct sensation I rode on 50T on the front, then shifted the back between a 21 and 17T in groups of 3 gradient changes. And between 0-3% I’m on resistance 5. Between 4-6% i shift my manual resistance to 6, 7-9% on resistance 7 and so on up to 12%. All the while keeping my cadence between 65 and 80 depending on the effort needed.

Whilst this felt like hard work and I was cooked at the end I did notice my heart rate didnt go over 145 - in the real world a 1km 8% climb would have me at 160+. My power output was always between 180-200 (seems also high but my FTP is apparently 320!! I confirmed this using Trainer Road too).

So am I doing this wrong and should maybe look for a higher cadence, smaller gear?

Any thoughts or tips would be welcome.

It’s all dependent on the quality of hardware you are using.
I can’t understand if you’ve averaged 180-200 watts how you’ve got an FTP of 320 unless your weight is ridiculously out.

If you’ve not fatigued your heart in the same way you would in real life I’d increase the resistance.

Alternatively if your budget allows purchase a smart trainer which will increase realism and accuracy.

This is where I am confused or thinking I am doing something wrong. When going up the steep stuff I tend to look for similar sensations in feel etc. as on the road.

I can easily hold 300w round the desert flats on a 50/17 ratio (acc. to ZWIFT) and a cadence of around 85.

Its when it goes uphill things go pear shaped mainly as I look for effort but also expect a drop off in candence and speed sensor reading. This is where I wonder if I should aim for a 34 small ring ratio and increase the cadence - but even this causes my power output to drop.

I guess maybe it’s simply trial and error until I get it balanced correctly.

Easily hold 300 W? Congratulations!
Have you a powermeter or speed sensor?

When using a classic trainer that has a manual resistance lever (I believe these are magnetic resistance trainers as opposed to fluid) you should leave the resistance on the specified level according to Zwift. When you pair your speed sensor and choose the trainer, is it listed? If not, then the accuracy will be WAY OFF!

Changing the resistance level will also change the power curve Zwift uses for estimating your watts, however, Zwift doesn’t know that you changed the resistance level so your power numbers will be inaccurate.


Yes, it’s listed and suggests L4 as the resistance. I just find it feels unrealistic especially when on the flat.

And when going uphill L4 on a “normal” 6-8% gradient and a 34/25 gear, for example, just doesn’t feel right.

Maybe I shouldn’t expect it to?

I know. Mad eh? It uses a speed sensor and cadence sensor. Set it to L5 but that should be irrelevant if power is calculated using weight, speed and cadence right?

No, it is very relevant. Zwift uses a power curve to estimate your watts. The power curve is set to L4, not L5, so if you change it the power curve is no longer correct.

You should leave it at L4 even if it doesn’t seem to feel right… unless you don’t care about the accuracy of your power estimate, then change it to whatever you want, but just know that you are not producing accurate power.

See this thread:

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If you are holding 300w on the flats then I’d expect you to go up the Alpe at something more than 180-200W.

I’d always aim for higher cadence when climbing. You wouldn’t climb the real Alpe in a 50, that’s for sure.

Drop the gearing and increase the resistance and see what happens.

FYI: doing this will result in bad power numbers, based on the power curve being set to L4 on the trainer. Again, it might “feel” more realistic, but Zwift is estimating your power based on the power curve when the trainer is set to L4. Changing that setting throws your power curve out the window.

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There is only one way to get exact numbers - powermeter. Yes, it is not cheap. But I bought one 2,5 years ago and today I say it was the best buy ever.

It depends - is Zwift a GAME or an INDOOR TRAINING TOOL for you?

Ride on!


Most definitely a training/fitness tool. I’ve no interest in racing etc, but I was concerned I looked a touch obvious I was riding to the wrong power.

I guess I’ll ignore that and simply go with what I am used to. If ZWIFT says my FTP is 300 then its only a benchmark at the end of the day.

Many times I have been passed by someone hitting 4 w/kg and I grab their wheel and hang on until I notice they don’t have the lightning bolt. Though I did use a Zpower rider last night for their draft I don’t chase them anymore.