Which Bike for Yumezi Grit? A Study in Zwift Bike Choice

Zwift recently rolled out Yumezi Grit, a new Makuri Islands route featured in the Pas Racing Series. The route is an almost 50/50 mix of dirt and tarmac, creating a bike choice quandary: do you go with a road bike for top performance on pavement, or a gravel bike so you’re fast in the dirt?

Let’s dive into that question. First we’ll look at how different bikes perform on this route in controlled solo tests. Then we’ll discuss how your strengths and the nature and location of the different road sections might affect your bike choice.

Related: Rolling Resistance on Zwift: Crr and Power Savings of Various Wheels

Solo Test: Road vs Gravel Bike

For the first test, I’m using Strava’s Comparison graph to compare the times of a fast road bike setup (S-Works Tarmac SL8 with DT Swiss 65 wheels) with a fast gravel bike (Cannondale SuperX LAB71 with Roval Terra Aero CLX wheels). These are basically the two fastest setups for this course.

A few notes to help you understand the chart:

• These tests were performed in an isolated environment: solo 75kg, 183cm riders holding a steady 300W.
• I tested using un-upgraded versions of both. If I compared the fully-upgraded versions of both, both frames would be faster overall, but the gaps between them wouldn’t change.
• I marked the dirt sections of the route in Strava’s chart below, so you can easily see how relative performance changes between dirt and tarmac.
• The purple line charts the time gap between the gravel bike and the road bike (which is the black line).

You can see that on the initial paved section, the road bike steadily grows a gap on the gravel bike. By the time they hit the dirt, the road bike is 7 seconds ahead.

Then they hit the Golden Forest descent, and the gravel bike pulls back 4 seconds. But as soon as we turn onto the pavement and begin the paved, slight climb up through the Fishing Village, the road bike gains another 11 seconds. By the end of this section, the gap is the largest it will be on the entire course: 14 seconds between the two bikes.

We turn a hard left onto the start of the Temple KOM, the road turns to dirt, and the gravel bike begins to quickly claw back time. Notice how (and this is important!) when the climbs get steeper, the stronger bike pulls ahead faster. This is true on paved roads and dirt.

By the time we leave the Temple KOM dirt, the two bikes are tied.

But the route ends with just under 1km of paved, flat road. During that time, the road bike gains another 3 seconds on the gravel bike, finishing 3 seconds ahead.

Solo Test: TT vs Gravel Bike

Out of curiosity, I ran the same test, but swapped out the road bike for the fastest TT setup available (the Cadex Tri with DT Swiss 85/Disc). This really doesn’t relate to the Pas Racing Series (or most Zwift races) at all, but it is interesting data if you’re racing a time trial on a mixed route!

Here, you can see the TT bike is much faster than the gravel bike on paved sections, gaining 11 seconds on the first paved segment.

Then, on the dirt descent through the Golden Forest, the TT bike actually gains 2 more seconds! Chalk this up to the TT bike’s higher weight and greatly superior aero performance.

The gravel bike loses more time (15 seconds) to the TT rig on the paved climb through the Fishing Village. Then we turn onto the Temple KOM, and the gravel bike pulls back a handful of seconds, but only on the uphills.

After losing more time on the paved finish, the gravel bike finishes 24 seconds behind the TT bike.

The simple takeaway here is this: a TT rig is around the same speed as a gravel bike on flats and descents. More precisely, the gravel bike is slightly faster on flats, while the TT bike is slightly faster on descents. On dirt climbs, the gravel bike is faster. And if the road is paved, the TT bike is faster.

Other Considerations for Yumezi Grit

Of course, the tests above were done in isolation. What happens when you take on Yumezi Grit in a pack of 50-100 riders, with some on road bikes and some on gravel? And which type of bike will deliver the best result for you?

That’s a more difficult question to answer. But here’s how I’d look at it…

The race begins with a 4.1km lead-in from the village start pens. That means riders have a bit of paved climbing, then the Temple KOM dirt section followed by a bit of flat pavement, before lap 1 begins. (And here’s where I’ll note that, if my test charts above included the lead-in, the gravel bike would come out ahead by a few seconds!)

If there are enough gravel riders in the peloton, the lead-in could prove to be crucial. Gravel riders could attack the Temple KOM, create a gap on the roadies, and never be seen again.

Alternatively, the lead-in may be a big nothingburger, with gravel riders not pushing hard enough to create those gaps because they are wary of breaking away so early in the race.

Will fortune favor the brave? Hard to say.

I consider the first two sections of each lap to be sort of a wash: roadies get a slight advantage on the first ~1.2km of pavement, then gravel riders get a bit of rest in the Golden Forest.

The paved climb up through the Fishing Village is where the gravel riders will suffer most, because road bike riders will be attacking, knowing they have to hurt or drop the gravel riders before the Temple KOM. Fortunately for gravel riders, this is a very draftable climb (averaging just 1.6%). If gravel riders can sit in the wheels and stay in touch with the peloton to the Temple KOM turnoff on lap 2, they’ll be in a great position to win the race.

The Temple KOM dirt section on lap 2 is where gravel riders must push and create a gap on the road riders in order to have a shot at the win, since road riders will have a big speed advantage on the paved finish.

Gravel riders’ attacks will bear the most fruit on the uphill portions of this segment. But keep in mind, road riders may hit the Temple KOM dirt fresher than gravel riders, having just come off a paved climb!

If gravel riders can hit the final paved section with 5+ seconds on the road riders, they can take the win. But if road riders survive the Temple KOM in the front group, they’ll be heavily favored to win.

The Pas Normal race is 2 laps long, and my guess is that the lead-in and first lap will be muted versions of the second lap. Riders will be more concerned about staying in touch with the front group on the first lap, while they know they need to create actual gaps on the second lap.

So what’s the best bike for this race? As someone who suffers on climbs but sits in easier on the flats, I’m leaning toward the gravel bike, as I want the advantage on the final key climb.

But here’s the thing: if I were a stronger climber, I might lean toward a road bike and plan to attack hard on that climb up through the Fishing Village, pushing to hang with any surviving gravel bikes on the Temple KOM dirt so I hit the flat, paved finish in the front group with the fastest bike available.

Your Thoughts

Zwift has set us up with a real bike choice quandary with Yumezi Grit. It will be interesting to see how the races unfold.

What are you going to use for the race? Share your thoughts below, and after you’ve done the race… share how it went!