Opinion: Let Me Feel the Draft on Zwift

September 13, 2019

LAST UPDATED September 13, 2019

Now that Zwift has rolled out FutureWorks, I find myself thinking of new cycling features they could release for us to test. And I keep coming back to the draft.

Drafting Today

We know drafting on Zwift comes with its own set of challenges. If you doubt that Zwift drafting is a unique skillset, just watch an experienced outdoor racer hop onto Zwift for the first time and try in vain to hang with a hard-charging pack. They’ll fly off the front, then ease up and get spit out the back.

Why does this happen? Because drafting on Zwift is very different than drafting outdoors, for several reasons:

No braking: without brakes, you can only change your pack position by increasing or decreasing your power. While this is what experienced racers do outdoors, a little bit of braking still comes in handy.
No steering: when the game moves your avatar right and left, you don’t get to choose where and when you “slot in” to the pack.
Riding through others: it’s too easy to ride through others in the Zwift pack, while in the real world if you tried the same tricks you would need to move around riders to avoid crashing.
No draft “feel”: when you move out of the draft outdoors, you feel the air hit you immediately. On Zwift, you feel no change, as resistance does not change based on your drafting status.

From the items listed above, braking and steering are certainly coming down the road–the new crop of smart bikes already has buttons and levers to make it happen once Zwift to adds it to the game.

Riding through others is an issue Zwift can change in their positioning algorithm.

But I want to focus on the draft “feel.” Let’s dig into this a bit.

Feeling the Draft

Most cyclists understand the basics of drafting, since its an integral part of group riding and racing. Being “in the draft” means you experience reduced air resistance, because riders ahead of you are blocking some of the wind.

Typically, cyclists will tell you that drafting another rider reduces air resistance by 30%. But a recent supercomputer-powered study said that drafting in a large pro peloton can reduce air resistance by as much as 95%. Amazing!

What if your smart trainer’s resistance automatically dropped a bit when you entered the draft in Zwift… and increased when you left the draft? What if drafting behind twenty riders felt different than drafting behind just one?

Would that make the experience more intuitive and realistic? I think it would.

(It’s worth noting that other indoor cycling platforms support some sort of “draft feel”–Tacx Desktop Software and Veloton are two which come to mind.)

Slowing the Pack

One potential benefit of “feeling the draft” may be a reduction in overall group speeds, especially in double draft races. Currently, the “churn” at the front of the pack leads to artificially high speeds–I would guess 2-3mph too fast.

Perhaps if riders could “feel” their position in the pack things would calm down a bit, group speeds would drop, and breakaways could stand a better chance of sticking.

Those Devilish Details

Of course, implementing this in Zwift is not as easy as Jon Mayfield snapping his fingers. Ideally, Zwift would be able to send a simple “drafting factor” to our smart trainers, just as they send wind resistance, slope, track resistance, weight, and other parameters. (Smart trainers combine these parameters to set overall resistance multiple times each second.)

Here’s the thing: smart trainers use two different wireless protocols: ANT+ FE-C (ANT) and Bluetooth Smart FTMS (Bluetooth). The ANT specification does include a drafting factor. But the Bluetooth specification does not.

So Zwift would have to hack the Bluetooth side of things for now, perhaps just dropping overall wind resistance to mimic drafting. Perhaps Zwift could push for an update to the Bluetooth FTMS service, which hasn’t been revised since February 2017.

But for now, I would just be happy to see Zwift roll it out under FutureWorks for ANT+ FE-C users, so we could give it a go. It’s just one parameter, which hopefully means it would be easy to add much like Zwift added the weight parameter to ANT+ FE-C trainers almost exactly one year ago.