watts per kg

(Simon Crerie [TFC]) #1

 I noticed that many group rides set classifications based on w/kg, in order to group similar abilities.

How can this be.

Say the classification is 2 w/kg, then someone weighing 100Kg will ride at twice the speed as one weighing 50Kg, if they are able to ride at 2 w/kg


Would not classifications based on ave speed be better irrespective of weight 


I am referring to races on flat courses

(Mark Hewitt) #2

Yes, you haven’t missed anything! I think it stems from Zwift putting quite a lot of emphasis on w/kg in the riders list and that on the old watopia loop it was a decent way of grading ability but you’re quite right in your speed analysis.

(Michal Wozniak TeamPL) #3

100% more power is 25% more speed. So they will be only 25% faster not twice.

But you are right. Power profiling for flat terrain races/rides should be based absolute power values, not relative. W/kg are good for very hilly or mountainous rides

(Stef Levolger) #4

Zwift provides all desired options, however it’s up to the community to choose which they use. And thus far most have gone down the route of w/kg, despite its shortcomings on many of the flat surface routes.

Average speed classifications also have their own downsides however. Given ranges are often quite large, e.g. 27 - 32, 32 - 37 or 37 - 42. Such a 5 kmph gap is a rather large one. Many may struggle. Furthermore, with no given wattage rates, on small climbs gaps may very easily form.