Strange camera behaviour at 60 FPS on PC

There is a strange camera behaviour when the framerate on PC is 60FPS. It is as if every time it hits this threshold, the camera zooms out and in, almost like a ‘push-pull’. On a good graphics card where 60FPS can be maintained, this happens almost constantly. When framerate drops, it stops happening.

This has been widely reported by other PC users on the ZPCMR facebook group.

Definitely an issue that seems to show up more if you are running Zwift to a TV instead of a monitor since most TVs cap at 60Hz (FPS) even if your graphics card is capable of handling better FPS.

I’ve been running into this a lot lately on a 65” TV and might have to look into a smaller PC Monitor mounted in a portable tripod in front of my bike if this keeps up. Makes it nauseating to look at the screen when it does that.

You can manually turn Vsync off to allow higher than 60fps but the trade off is constant screen tearing. Not ideal in a game where the scenery should be passing by smoothly. Interestingly it happens to me even using a variable refresh rate monitor if circumstances dictate that I’m at or around 60fps, so it doesn’t seem to be limited to TVs or fixed refresh rate displays.

Here’s what it looks like in Zwiftalizer (I’ve added the green line at 60fps).

Every time the frame rate hits 60fps (so approx. 10:52, 10:53, 10:55, 10:57, 11:08, 11:10, 11:11, 11:12 and 11:17) I saw this rubber banding of the camera. Whenever I was consistently below or above 60fps it was fine.

I’ve run some additional tests on this.

I have a GSync compatible display, 48-60Hz.

I have Vsync turned on, so the max FPS is 60. On this setting, I get constant rubber banding. FPS is not dipping, but I think due to the way VSync works it will naturally flutter between 58/59/60 fps and every time it does, the camera zooms in and out.

If I set a hard FPS cap in Nvidia settings to 58FPS (GSync still on) this weird camera behaviour goes away completely.

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What seems to happen with this is there’s a momentary dip on the frame rate counter of 2-3fps below 60fps which then catches back up, pushing the reported frame rate momentarily above 60fps by 2-3fps until it settles back. This happens even when the GPU is well within its comfort zone and there’s no CPU bottleneck, so there’s no reason for the frame rate to change from a solid 60fps. It happens on both low end and high end hardware. The dip causes a stutter as frames are repeated on the display, then the ‘catching up’ as the frame rate spikes over 60fps coincides what you see on screen as the zooming back and forth. The best solution is therefore to cap the frame rate at 61fps, which allows vsync to work as intended most of the time but stops the spikes above 60fps being too large and invoking the annoying zooming effect.

So whatever causes this problem seems to be tied to vsync in some way. This damages the experience for users with TVs; you get both stutter and this zooming effect even at times when the components are perfectly capable of maintaining 60fps. It’s as though the game uses the 60Hz tick of the display as a point of reference in some way and if that goes out, the game reacts with this behaviour.

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If you’re not going to address and optimise the ridiculously erratic frame rate on Makuri Islands irrespective of hardware specs, at least do something about this obnoxious and nausiating visual bug.

Bump. Seeing as you’ve made the rest of the game as bad as Makuri.

Zwift please fix the rubber banding issue that occurs on PC with Tv’s at 60FPS.