ZWIFT Drafting (V1.0.8743)

(Craig Hoskin) #1

The update to the drafting today quite frankly … was AWESOME.

It was noteably easier to get out of the draft (and never felt stuck).
With a bit more effort, but not hugely excessive, it was possible to get back onto a bunch.

Staying with a bunch was as good as normal.
Nice work everyone in the Programming area.


(... david (aka "setuid")) #2

I concur with Craig. After the 2nd-to-last update and the last one (which came in rapid succession in the same week), the drafting feels remarkably realistic.

I’ve been more than vocal about the drafting “bug” out on Zwift Riders on Facebook, and with this latest set of updates, I’m able to slide in and out of a draft very easily. 

Others are still complaining on Zwift Riders about not being able to push past the draft once they’re in, but it seems to be working fine. 

Keep up the great work! 

(Duane Gran [Vision]) #3

Agreed.  It feels right.  The only thing left I’m wanting for in the drafting simulation is some kind of visual aid that helps to internalize when you are in the draft zone, but I think you have the physics aspect worked out well and this was no small achievement.

(Christian Wiedmann [X] 50) #4

I’ll dissent here. I was doing a sweet spot ride today and felt like I got stuck several times trying to pass other riders. I still would like the option to turn this drafting aid down or off.

(Wes Salmon (Zwift HQ)) #5

I too felt like I got “stuck” behind both regular riders and smurfs on a solo training ride yesterday (Nov 30th).  I can tell when I get stuck because I now watch my MPH as I’m passing someone where I think I’m going to get stuck.  When it happens my MPH drops 2-3mph while my power remains the same on flat ground.

I’ll try the ZTR race tonight and record it so I can report it if it happens again.

(Lee .azy) #6

Dear Zwift,

Thank you very much for reading my previous post on issues with drafting and fixing it so quick.

Keep up the good work…

Ride On!


(Simon Oxenham [VC10]) #7

Nope… Still way too sticky. Please explain what you’re trying to achieve with the stickiness? Why would you ever want to slow down when approaching a slower rider?

Still awful IMO 

(... david (aka "setuid")) #8

What’s interesting, is that many of us are not affected by the so-called “stickiness” and some (including myself) feel that it’s almost perfect, models exactly how it would behave in real-life. 

But others are now negatively impacted, where they weren’t previously. Reverting it to the prior behavior, will fix it for some, and break it for others. 

So what’s different about You vs. Me in this setup?

Why does it work perfect for me, and not for you?

There’s got to be something more subtle going on here; either a configuration difference or something unique about your trainer/ANT+ adapter that I don’t have. 

Let’s do some information gathering. I’m using a handful of Suunto ANT+ adapters, a Quarq power-meter and a CycleOps Fluid2 trainer. What does your setup look like? 

(Wes Salmon (Zwift HQ)) #9

Yep the sticky wheel is still a problem for me as well.  Last night in the ZTR-B race I was in a group of about 6 doing about 2.8w/kg and we came up on a slower solo rider (doing about 3/4ths our speed).  I was the unlucky one who did not auto-path around him and got stuck to his back wheel as the rest of the group took off as if they hit a NITRO button.  I had to sprint 6w/kg+ for 11 seconds to get back into the group.  No fun having to burn a match during a race to overcome a bug. :frowning:

Here’s what it looks like on Strava:

This is just one example.  I also saw this happen to another rider in the group during the neutral rollout.  We were both at the front and we came to a solo slower rider and he stuck to the wheel and immediately disappeared off my screen as he fell back like he had locked up his brakes.

There were a few other times where I got sticky wheels/shoulders but none as obvious (and painful) as what is illustrated above.

(... david (aka "setuid")) #10

Here’s the rub, and it seems unintuitive, but perfectly models how you get out of the draft in real life

If you’re riding and slam up behind another rider in Zwift, and get “stuck”, your first inclination is to pedal harder to “pass”, so you put down more power. And more. And more. And you’re still not passing until you put out enough that you pop out, or the other rider slows down slightly and allows you to pop out (this is the key hint here).

But instead, if you let up on the pedals slightly, OR increase your cadence before you reach that rider’s draft, you’ll cleanly slip around them. Drop your cadence for half-a-revolution and you won’t get stuck.

You wouldn’t stay 8cm behind a rider in real life and then just hit the afterburners to pass. You’d slow your cadence, drop back, possibly stand up and sprint past them. It’s the subtle slowing/reduction in cadence (not power) that will get you past a rider you’re drafting.

I realized this when I seemed to be the only one who never got stuck in this new draft zone that everyone else gets tangled in, but that’s because I instinctively slow my pedaling as I reach their rear wheel, and if I want to draft, I match their speed, if I don’t, I increase my cadence (not power) and pass them around on the side.

Try that, and you might be surprised how well it works. I’ve mentioned the same technique to others who were getting stuck, and now they’re not, so it does work, and not just in my own setup.

(Wes Salmon (Zwift HQ)) #11

Nothing about this bug models real world group racing and drafting.

In the real world, the entire group would have to negotiate a slower rider by changing how they are riding. This includes steering (which none of us control), position in relation to other riders in the group (which none of us control) and power they can maintain without burning extra.

The way this bug manifests itself is that only ONE person pays the penalty. The rest of the group can ride at exactly the power they want and completely pass by and partially through the slower rider with zero penalty. They are getting 100% benefit of a draft on a slower rider whereas in real life they too would have to adapt to the slower rider and most certainly crash if they passed through him like they do on Zwift.  In the meantime, the unlucky one stuck to the slower rider is having their speed reduced by ~20% and being forced to recover from this reduction with a 3-4x sprint effort to rectify the situation.  That’s assuming you can unstick yourself in time.  In a previous race I was stuck to the wheel of a blue rider on a climb long enough to lose the group and never recover.

I’m glad that you are not being impacted by this bug, but realize that some of us are and it really sucks when we hit it in a race and no amount of saying “ride different” is going to change the fact that when this happens to someone, it is 100% broken.

(Duane Gran [Vision]) #12

if I want to draft, I match their speed, if I don’t, I increase my cadence (not power) and pass them around on the side.

The above explanation doesn’t really compute for me.  Power is the only important factor determining if you pass or stay in the draft, cadence is irrelevant but maybe you mean lower cadence as a proxy for lower power to ease back.

My real world experience is that my effort at the same speed becomes somewhere around 20-30% less in the draft and if I increase power I move up and pass, provided that my increased power overcomes the ~30% wind resistance.

I feel like a broken record on this issue but I genuinely feel like nearly all drafting problems are visualization problems.  If there is some form of visual drafting indicator a person would know if they are in the zone and when they pop out they would anticipate jumping up the power to overtake someone.

The latest update has made the draft less “sticky” but I too have still gotten pinned to someone’s wheel.  It feels like someone reaches over and grabs your brake lever.

(... david (aka "setuid")) #13

Nope, I meant what I said, and it’s specifically why I called it out in parens several times. You shift your gears, maintain the same power, but change your cadence (in Zwift) to slip around.

But again, I’ve never, not even once, been “stuck” in this draft area that others claim is unbreakable, so I don’t have a way to test it myself. I can’t cause myself to get stuck. I slip around riders on Zwift all the time. If i’m behind them drafting to get a bit of recovery in my legs, then shift my gears, change my cadence and I slowly pass around them, as I would in real life.

I don’t have to put down any sort of super-human power to break out of some force field, it just happens naturally, when you change your cadence (not power).

Perhaps that’s where the issue is within Zwift; the change in cadence while keeping power constant gets the algorithm to recognize that I’m passing vs. Zwift thinking I’m still trying to stay drafting.

(... david (aka "setuid")) #14

@Wes, let’s set up a time when we’re both on so we can test this by drafting each other.

I don’t represent Zwift, but what you’re describing is something I’ve repeatedly tried to reproduce hundreds of times (both when the drafting was buggy and I would constantly get throw off the back, while I was doing 2-3x the w/kg and still dropping out ) and now. Drafting bugs have been a pet-peeve of mine since early on, and I’ve ranted about them enough, but I’m serious in my desire to help figure this out, for you and for Zwift.

If you’re flying up at 23mph/300W/2.8w/kg (for round figures) and come up behind a rider/NPC doing 20mph/250W/2.2w/kg, you’re saying you slam up against them, like someone pulled your brakes, and you slow down and get “stuck” there, instead of pass around them?

My experience has been that in that exact same situation, since I’m already going faster than they are before I reach them, I slip around them unless I slow my speed down to intentionally get behind them and draft.

If, while I’m now drafting them, I want to break out and pass, I simply change my cadence (again, not power) and I slip around and leave them behind me.

If that’s a set of steps you can’t reproduce, I’d love to see what the difference is between our technique, equipment, configuration and setup that makes it so impactful to you (and others who are affected) and not at all to me (and others not affected).

(Wes Salmon (Zwift HQ)) #15

If you’re flying up at 23mph/300W/2.8w/kg (for round figures) and come up behind a rider/NPC doing 20mph/250W/2.2w/kg, you’re saying you slam up against them, like someone pulled your brakes, and you slow down and get “stuck” there, instead of pass around them?

Yes, that is exactly what this bug is and my experience is that only one  person is the victim when it happens.  The rest of the group takes off like they are on jet fuel. I can pass 100 riders on a 30mi race with no issues at all but it only takes one occurrence of this bug ruin my ride (like it almost did last night and certainly has done previously, which is why I stopped racing for a week).

I’d say the repro rate of this is less than 10%.  But of those 10%, they are 100% infuriating when they happen in a race or large group ride.

(Darth/Lady Bane) #16

I spent a lot of time in the spring on the beta and the drafting seemed fine. Sure you blew past a rider now and then but like in the real world, you sometimes over shoot and have to balance the distance to the wheel in front of you. 

With the weather changing I have been on the past week. Drafting is horrible, especially in groups, the tendency to be locked on to someone is quite ridiculous. So 10% of the time it happens, well if I pass a hundred people on my ride it has happened 10 times more than I want.

I prefer the old drafting, at least you were never wasting energy. 


(Simon Oxenham [VC10]) #17

This is quite a recent thing Darth Bane… From memory this ‘feature’ was introduced three updates ago. Before for that it was fine

(... david (aka "setuid")) #18


  1. Old drafting behavior, worked for half, broken for the other half.
  2. New drafting behavior, broke for the previously-working half, now working for the previously-broken half.

It’s not broken for everyone, nor working for everyone. From what Wes said above, it only happens in larger groups and not 100% of the time. When riding solo, passing riders becomes easier.

I wonder if we could see the ‘shape’ of the drafting field around us, if one rider just happens to get stuck in the “Venn Diagram” section of the drafting zone overlap and can’t get out.

Making those drafting areas visible, with say a 'set gDebugDrafting = 1" in the config file would be one way to help debug and diagnose this for Jon Mayfield and team.

A conundrum.

(Simon Oxenham [VC10]) #19

Definitely doesn’t happen every time, but it’s not just restricted to larger groups


(Simon Oxenham [VC10]) #20

It’s possible to put in a small acceleration when approaching a slower rider to minimise the problem, but when you’re on the limit drafting a faster rider this isn’t always possible