ERG Mode and shifting

I created this under tips and troubleshooting this morning, but thought I’d throw it into the general discussion as well.  Any suggestions would be appreciated.  Thanks

I’ve been using ERG mode on my Kickr for about eight months.  I started with 50x14 gearing, but about a month ago realized the I was having trouble maintaining 80rpm on flats and steep gradients (above 10%) were pushing my consistent watts above 350 just to keep the cranks turning.  Not sure if this was due to automatic power increases by Zwift as I became more fit?  I’ve recently upshifted to 50x15 and seem to have found a happy medium. 

That being said, I tried Alpe du Zwift for the first time yesterday and really struggled on the early sections.  I shifted up to 50x17 and was able to handle the climb.  I averaged around 260w versus the 340+ in the harder gear.  Is this cheating?

I’m 51 and a large rider - 6’5" @ 225lbs.  I want to work hard to continue to improve but don’t want to injure myself by pushing super heavy gears at low rpm.  Would appreciate any advice.  Thanks

Hi Michael, 

I’m a bit confused by your post.

When you’re in ERG mode, there are no ‘hills’. That is - In Zwift, ERG applies only to ‘workouts’ where the resistance that you feel being applied to your Kickr is a function of your cadence and the power target, in Watts, for a given workout interval.  The faster you spin, the less resistance you’ll feel for a given wattage.  On the other hand, if watts remain the same but you turn the cranks at 60 rpm? It will feel ‘harder’ even though your power output is unchanged.

Your gear choice has (almost) no impact when in ERG mode.  If you shift gears, the trainer will automatically adjust resistance and your effort will feel exactly the same for a given cadence.  Whether you’re in 34 x 20 or 50 x 14 makes no difference, except for the possible problem of hitting your trainer’s ‘resistance floor’ in larger gears when a very low wattage target is prescribed by some workouts - but that’s not an issue here. 

The key point here is that ERG mode disables hill simulation. There is no additional resistance applied at any time because you’re going up a hill  when you are riding in ERG mode.

Now - when you are ‘just riding’ and you feel additional resistance while you climb a hill (and you see your power on the display going up up up?) that’s a very different story. But - unless you are incredibly strong and fit? There’s no good reason you should be climbing long 10%+ gradients in your 50t ring.  You almost certainly wouldn’t do it on a real hill outside, so you shouldn’t be trying to do it in Zwift either.  When you  are not in workout mode , ERG is off and shifting is everything! You have lots of gears to choose from and you’re supposed to use them.


Okay, I am definitely confused then.  I suppose I need to check my settings when I open Zwift.  Is workout mode considered the canned rides like “Road to Ruins” where you can’t choose the direction you go?  All I can say is that I’ve never shifted and the effort always gets harder as I climb.

Hi Michael,

Looks like you posted this in a few different forums here but I’ll offer a similar response. 

It seems like you’ve been indoor training for a while. Have you done an FTP test recently to make sure your FTP is appropriate for your training workouts? 

If you’re using the appropriate FTP for your fitness level during your Zwift workouts, I suspect that there would be less risk of an injury. 


No. “Road to Ruins” is a route that you would pick by clicking on the “ROUTE” dropdown.  Where it says ‘RIDE TYPE’ with ‘Just Ride’ beneath it?  - this would start a ride with hill simulation (read: no ERG mode).  If you stay in a single gear, of course it will get harder to pedal when going up a hill. You’re supposed to downshift as needed.

On the other hand - if you were to click the blue ‘SELECT WORKOUT’ button, that would take you into the workout menu from which you could select a specific workout (ERG mode enabled by default when you do this). *IF* you select a workout, hill simulation is OFF even if you disable ERG mode.  You will still go slower up hills than you will on the flats for any given power output, but you won’t feel any increase in resistance caused by gradients.

 FYI ‘Just Ride’ is the default any time you launch Zwift, while the ROUTE default is the last one you rode at a given location.  You won’t enter workout mode / ERG mode *unless* you select a workout from the menu before starting your ride - and you can do any workout you want on any route you choose.  

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I’ve received responses on both forums… so I’ll provide the same update here since folks have taken their time to respond.

I’ve only done routes on Zwift, so no workouts.  I’ve wrongly assumed all along that ERG mode was active… so I’ve only used the 50x14 or 15 gear on all rides. I checked and the trainer difficulty setting is at 50%, which I believe is the default.

I re-rode about half of Alpe du Zwift last evening using my 34 chain ring on the climb.  I was able to maintain 80-85 rpm but I didn’t really notice much difference between a 7-9% gradient and steeper sections of 13-14%.  This seemed odd to me, so I downshifted  several times.  This resulted in spikes in power for a few seconds but my wattage would quickly settle back down to the low 200s.  Overall, the climb felt a little too easy.

I think I will move the difficulty level to 100% and retry.  Does this make sense?  Should also mention that I’ve done several FTP tests and they are similar to results I’ve from Trainer Road.  Thanks

Changing the trainer difficulty setting to 100% will definitely make the difference between 7-9% and 13-14% more apparent.  If you think about it, it’s not too surprising that the differences aren’t as large w/ the setting at 50%. 

Essentially, what you’re saying is this: In a low gear (34t x ?), the difference between a 4.5% (9 x 0.5) slope and a 6.5% (13 x 0.5) slope isn’t that noticeable, at least from a perceived effort vantage point. Chances are good though that even if you didn’t ‘feel’ it, that your cadence slowed on the steeper parts and ticked up again as things flattened out.

Looking at your last ride on Strava, your average cadence on the first 5 km of the climb (which seems to be as far as you went yesterday) was 71, w/ avg power of 228W. 

If that was in one of your lowest gears (you didn’t mention which cog(s) you used w/ the 34t chainring) - then it’s probably best to leave the difficulty where it is (50%) for now. If you have a few larger cogs to spare, then give it go @ 100% and see how you like it.



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I was a bit time crunched yesterday, so I stopped on turn 11.  The highest gear I used was 34x25.  Your math makes sense with regard to perceived effort.  I will definitely change the difficulty setting to 100% and give it a try tomorrow when the calendar flips back to Watopia.  

This was the advice I was looking for, so thanks.  Sorry to bother everyone with such a boneheaded question.  I think I should have read a little more about how Zwift works before plowing forward.

No worries Micheal, there are a lot of people here that are eager to help.

I really wish Zwift will relese a document like the one Titanium geek generated, it gives you a good base on how to get started and what to do.




Wow, that is a very comprehensive read.  I will definitely read through it this weekend to see if there is anything else I’m doing incorrectly.  Much appreciated!

Just remember it is a bit out dated, but it will give you some good info.

For route information I go to this site.