Which gear with ERG

which gear i have to use with erg mode? sometime to reach the watt i have to go over 100 cadence… i have to change the gear?

1 Like

Grab your popcorn!


Whichever gives best feel and good chain line in my mind. In my setup it is 52x17

For ERG mode to reach the watt, it doesn’t matter which gear you are in.
Your trainer should give you the wattage regardless of the gear.

You might just need to give the trainer a bit more time to reach the wattage, you shouldn’t be changing gears to get to your wattage.

Try holding one gear and the same cadence next time when it switches wattages and see if your trainer reacts faster.

There is a whole different topic on flywheel inertia and road feel that I am going to leave to the real ERG mode pro’s on the forum.

Check out these previous threads…


I think the issue here is just a lack of understanding about how ERG mode works. I fell into this myself. There is probably an ideal gearing, but forget about that for now and learn how ERG mode works.

ERG mode will set the power to whatever cadence you want. If you want to spin at 80, it will set the resistance properly for 80. If you want to spin at 90 or 95 it will do the same. The issue is that you are trying to match the power, rather than matching the cadence and when you dip under the power, you think you need to pedal faster to bring it up, but that’s not how it works. What worked for me is to try to hold a steady cadence. Try 90. pedal at 90 and keep it there and watch ERG mode match you, rather than the other way around.


That doesn’t sound like ERG mode at all. Firstly what equipment are you using and is it showing as using ERG mode in the device settings within the trainer road app?

an email into support@trainerroad.com might help as well

1 Like

You’re all completely incorrect.

Gearing DOES make a difference. Depending on the make and model of the trainer and the FTP of the user.

Trainers have both wattage floors and wattage ceilings for their braking systems and as such gearing does need to be selected accordingly, in some cases.

My personal example, this morning in middle front ring and second largest rear, the power will not go below 100W above 95RPMs. It will also not go above 231W if I’m in smallest front ring and third from smallest rear.

When my FTP was lower and using the small front ring this was more pronounced. Now my FTP is higher, therefore the Watts are higher and I use middle ring on about middle cog, it can pretty much cover most wattage variations.

P.S. I’m using a Tacx Flow Smart, so yes its low end but it still works pretty much just as well as the high end ones :stuck_out_tongue_winking_eye:


No, to be fair, it doesn’t. :wink:

1 Like

Go on then…

We are talking about how erg mode works, not the limitations of your specific trainer. ERG mode itself as a concept behaves as stated. Obviously if your trainer can’t handle the low end or the high end, then that’s just on your trainer. Doesn’t have anything to do with ERG mode.

1 Like

With respect, look at the OP, I believe what I have explained is exactly the issue.

1 Like

It ‘may’ be the issue, until the OP confirms what equipment he is using and how it is set up then it’s largely guess work on all our part.

More information required is the only definitive answer at this point, IMO.

1 Like

Easy guys. Let’s slow the roll a bit.

I think it is important to get some clarification from the OP before jumping to conclusions and proposed solutions.

There is minimal info in the OP. It hints at what could be a couple of issues, and possibly not even ERG mode in use.

No one is right or wrong and the goal is to help the OP. So please, keep the “absolute” types of statements out of the discussion.


@Fabio_Sgambati can you answer the following questions?

  1. Are you certain that you are using ERG mode?

  2. What trainer are you using?

  3. What gearing are you using?

  4. Are you shifting during regular use?

  5. If so, when exactly are you shifting?

There may be more questions, but those are what come to mind right now.

For clarity on ERG, just to make sure we are talking about the right training setting:


This is mostly covered above.
Posting from a previous thread.

Gearing in ERG Mode

Technically, if you are doing target power training in ERG mode, gear selection does not affect your training. 260w is 260w in any gear. Ideally you want to strive for good cadence which is typically 85-95, but may be higher for sprints and lower when doing slow speed work. The instructions inside TR and Zwift workouts will often indicate what cadence to strive for. I have found that certain gearing (52t x 12) allow me to hold my target cadence at 90+ so I usually use that gearing. If my cadence starts to drop, shifting up one gear (easier) often helps me keep my cadence up.

But an easier gear combo has slightly different leverage action from harder gears, and when you ride in a harder gear your flywheel has greater momentum which also factors in. So there is some validity to using appropriate gearing on the ERG trainer to better target different muscles that are triggered by different gearing.

The short answer is “Ride in gears that simulate what you’re riding is like outside.”

What is ERG mode:

Does Gearing matter in ERG mode:

Although I mostly use Trainer Road and do structured training, I also use VirtuGo (like Zwift) and Zwift in freeride mode so I can ride around and practice changing gears specifically for climbing. It’s an excellent way to understand your gearing combos and your wattage output so when you get outside you can ‘replay’ what is working from your training. (I don’t have power meters on my mtb bikes). I have also started shifting to harder gears when doing low cadence high power intervals so I don’t have to slow my cadence early in erg mode. It feels right to me and my Kickr reacts very quickly so it seems to be good. I keep power smoothing on most of the time so I don’t notice the power jumps unless I dig into the workout data.

Hope this helps.


I’ve been using a Cyclops Magnus with a single speed bike with no problems in erg mode

1 Like

Thx to all for replies…
I use bkool pro device.
For exemple when target is 100 watt my cadence is 100, if i want to stay in a cadence between 85-95 i’m not able to reach the target watt and i need to shift… it’s a problem of my device? I see the erg mode enabled…

The Bkool is likely an issue. They lack a decent flywheel and I don’t know if they have a great “floor” and “ceiling” for wattage values.

Also, since it only uses gravity for roller engagement, the performance of the resistance unit and roller contact varies with rider weight and position.

It’s not my favorite trainer and I have seen a variety of issues from them over the years.

I’d suggest some testing in large and small chainring with steady cadence to see if the ERG mode works better for one or the other.


I use the smallest gear to make the smallest noise. My kickr adjust from that in ERG mode.

Recommend using ERG mode for interval or big variations of power and resistance when there are not much fluctuation of power to get used to the power variation and what gear belongs to what power for what cadence.