Why is it Harder to Ride with Genie than Constance on Zwift?

Zwift pacer bots offer a nonstop group ride for riders of any level, any time of day. The concept is great, let’s make a fake rider that just rides along at 2.0 watts per kg, and anybody that wants to join a ride around that power can do so. You don’t need to produce Pro Tour power to keep up with the pacer bots;  the busiest groups on Zwift fall into the 1.5 to 2.0 watts/kg power groups. The 1.5 to 2.0 watts/kg groups are so busy that Zwift has divided them up into many smaller groups where some ride hilly courses and now vary pace on climbs to keep things interesting. 

Riding with 3.7 Watts/Kg Genie

I have a Zwift friend who was telling me how hard it was to ride with Genie. Genie is the bot that rides at 3.7 watts/kg. You would think you could draft at less than 3.7 watts/kg if the pacer bot was riding that power output, but clearly he couldn’t and would get dropped. We investigated further. When I rode with Genie I noticed there was a massive group of riders, some ahead and some behind, and yes clearly it didn’t seem I could draft at much under the advertised power.  The question is, “Why? “

Riding with 4.2 watts/kg Constance

It was time to compare with Constance. Constance is the hot shot’s pacer bot, the strongest pacer bot who rides at 4.2 watts/kg. All amped up and ready to try to hang on, I noticed there was something different about riding with Constance though. It felt easier. There were only 6-8 riders in the group and all were slotted in a nice line behind Constance. 

Speed Comparison Between Genie and Constance Rides

Comparing average speeds between riding with Genie and riding with Constance reveals a smoking gun as to why Genie is so hard to keep up with. Riding in the 40-rider group with Genie averaged 27.0mph on the flattest part of the course. Riding in the 6-rider paceline behind Constance averaged 26.0mph on the same course! Why would the 3.7 pacer bot group be going that much faster than the 4.2 group? Drafting. 

Genie is drafting, while still riding at 3.7 watts/kg. Genie’s group is so big, that Genie is rarely, if ever, the rider on the front. This means Genie is riding at 3.7 watts/kg just to stay in the draft. If you consider the drafting rider is saving 25-30% power compared to the lead rider (exact amount depends on speed and rider size) if enough riders are pulling Genie the front rider will be putting out 30% more power or in some conditions as high as 4.8 watts/kg! 

Maybe Constance is respected, or perhaps the smaller group is just trying to stay with her. The smaller group makes riders more sensitive to where they are in the pack.  As a rider, you don’t want to gapped, so trying to stay on the pacer bots wheel is the goal. If Constance is staying on the front, riders behind Constance will save the same power and could be riding as low as 3.2 watts/kg comfortably sitting in Constance’s draft. 

If you’re having trouble keeping up with 3.7 Genie, then try riding with 4.2 Constance. I think you’ll find it’s easier on flat courses. On hillier courses the differences will be less, or if more riders start riding with Constance then that ride could end up like the current Genie group (much faster). Anybody on the front of the Genie group should stop sandbagging and start riding with the Constance group! 

Riding in Zwift’s largest pacer groups

The largest pacer groups on Zwift are the 1.5 watts/kg and 1.8 watt/kg groups, both with over 100 riders every time I see them. I’ve ridden with both groups on various courses and you’ll find you need to ride the advertised pace as the pacer bot is always drafting. Just plan accordingly and try different pacer bots to see which best suits your style and planned ride.