Trainers need ERG brakes

Wouldnt it be nice if after you do a 1 min V02 max interval and transition into a rest interval if you could hit a button to slow down the flywheel?


?? what would that help with anything, like - at all?


It would get the flywheel down to a normal speed again so you actually have some resistance to pedal against.

As of now, when you finish a hard effort in ERG and resistance drops to recovery, you end up effectively coasting with minimal load until the flywheel slows to the speed it had before the hard interval.

I used to mess with swapping to RES mode at time’s to get some load and then back to ERG once the flywheel slowed. But I just live with the coasting these days.

This is a basic feature I’ve thought about as it’s been mentioned a time or two over the years.


Kickr Bike does have brakes. I abuse it to create higher resistance during sprints.


As someone with young kids, they’ll often walk into my small training room / office and want to come up to me while I’m in the trainer. I usually grab the brakes for an instant trying to stop the flywheel motion then realize ‘duh, that doesn’t work with my wheel off trainer.’


If it was actually inly a second, no one would care….but it is a lot longer than that on most trainers, especially those with heavier flywheels.

  • First of all, it takes well over a second (10-15 from memory without digging into ride files), and the obvious answer is that some people do care. The OP for one and me for another.
  • No one made that claim and regardless, there are plenty of requests tossed out that don’t have anything to do with gainz, but more to do with convenience of use. This happens to be one of those.
  • I actually do that at times now. I can swap to the big ring which immediately drops my cadence about 30 rpm in all cases. But even with that, it doesn’t change the functional flywheel speed so the load is still low until the flywheel slows.

  • So that and the trainer mode swap are possible workarounds, but asking for a more direct change is still a fine request IMO, even if you don’t like it.


An 80% drop in load is great and always welcomed by me. But having almost literally nothing to pedal against is a different thing. Sometimes I might want that but most often I like at least something to push against.


I think there’s something in this idea.

The emergency stop use case noted above is similar to a treadmill emergency stop.

Given the maximum resistance of many smart trainers is over 1500w, I don’t think it has to be an additional friction brake. A software approach that uses up to the maximum unit resistance may be adequate.

How the software solution is implemented is where it gets interesting. As a hardware maker, how do you make this user experience as easy as possible, safeguard against accidental stops, and bypass asking all the SaaS companies to add yet another button to their UI?

A Bluetooth start/stop button (or just a small factory-style stop button) with multiple attachment options could be placed, clipped, or wrapped to anything nearby or on your trainer-attached bike. It overrides all other Bluetooth connections and raises the unit resistance to maximum until the user hits start again, or until the RPMs are zero. Perhaps preferences can be adjusted.

Typically trainers catch up waaaaaay faster than your momentum outside. You would just be exacerbating the problem

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100%….For me, it actually impedes my recovery. So the idea that it won’t potentially impact your gains doesn’t really hold water since not recovering fully / properly can leave you short on the next interval


Takes my H3 a good 20 seconds to slow down.


Despite the general consideration of having inside training match outside, there are clearly reasons that having differences between them is a benefit, not a problem. ERG mode itself is a perfect example and welcomed by those who use it.

It’s quite jarring on my Tacx Neo 2.

I did some 30/30s last week and the resistance drops off a cliff to get me from ~450w > 145w. It’s like if you were pushing hard up a hill and your chain suddenly came off… 9 times in 9 minutes for 3 sets. It’s crap!


Definitely not a must but here’s where I would use trainer/flywheel brakes:

  1. Zwift - brakes could be useful in just about every situation they are useful in real life (save avoiding crashes or cars). Examples - staying in the draft in group rides or races, slowing down enough to activate the turn around feature, slowing down so you can start an effort at the preferred course point, slowing down on descents if you are doing hill repeats so you don’t overshoot the end of the climb etc

  2. Slowing down the flywheel would make it easier to stand up and have some resistance to pedal against

  3. Slowing or stopping the flywheel if kids or dogs are getting too close.

  4. And the off cited slowing down quickly so you can have some resistance early in a rest interval (see #2 as these would work together).

And, there are probably more …


The hardware button could use a continuous or discrete (stepped) control user input instead of the binary on-off switch I posted above.

There has to be some existing commercial-grade dial or slider that can accommodate this.

If you’re spinning out, you dial it up a little. Heck, it could spring back to zero-added resistance within a couple of seconds because you modded a jacuzzi timer dial.

A smarter software to return resistance faster would be 10x, no, 1000x more ideal, though, in this post-interval use case.

Respectfully disagree, using a Neo2 I’ve just learnt to unload my legs as soon as the resistance drops off. I don’t mind it :slight_smile:


All I can say is I strongly disagree.

Fair enough - I sort of got used to it after a while and started to anticipate it like you said. I only do on/offs like once or twice a year, so I’m just not that accustomed to it. I’m currently doing longer VO2s in resistance mode, and it’s just like being out on the road - dump a loads of gears when the interval’s over. 30/30s are too finicky for resistance mode in the mobile app hence using ERG.

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The new Play controllers now provide a braking feature…it doesn’t do anything for your flywheel, but it will help your position with other riders in the game.

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