Four by Four TT categories

Racing
1

I noticed that on the “Four by Four” race series, the “TT Club” events are organized by categories A-D (based on W/kg), but the other event types are organized by Racing Score.

Is that expected? I haven’t done a lot of TT events, but I have a TT bike I’d like to put in the miles to upgrade.

I just found the difference in race organization surprising.

2

James Bailey wisely stopped using ZRS for Zwift TTs some time ago, reverting to Category Enforcement, used for a majority of races Feb '22 until summer '24.

CE isn’t perfect, but it’s heck of a lot better than any incarnation of ZRS we’ve had for almost two years.

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3

Thanks for your reply.

I’m curious, who is James Bailey?

4

works for Zwift, head of the events team or something like that

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5

If you have questions about TT Club, and you happen to be a Facebook user, I recommend posting over there: https://www.facebook.com/groups/zwiftttracingclub

6

Thanks. I don’t need information (or have enough curiosity) to draw me back to Facebook.

7

Given that TT’s tend to be flat, I would think that categorizing by watts (instead of W/kg) would be effective.

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8

Speed on zwift scales much closer to w/kg than watts, even on the flat. CdA is calculated using height and weight, so heavier people are less aerodynamic.

Unfortunately zwift doesn’t have any native categorisation options that line up with their physics model.

9

Thanks for the explanation. That makes sense within the Zwift version of the universe.

10

Here’s a tidbit I found about it on Facebook…

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11

Thanks for posting the quote.Using zFTP (in watts) makes sense for a TT event.

That leaves open the question of why the Four by Four TT events are categorized by W/kg, instead of zFTP.

The Event form says Cat D is 1.0 to 2.5 W/kg. If the quote from James is accurate, that should be zFTP instead. Or the text in the Event entries is wrong.

12

I can clarify that. The event is using Pace Group Category Enforcement, which puts you in a category based on W/kg for zMAP (around 5-6 minute power) or zFTP (often around 40 minute power) based on the thresholds in this document:

So the D category riders will have both zMAP no more than 3.2W/kg, and zFTP no more than 2.63W/kg.

13

Thanks much. Zwift does like to make things complicated and obscure.

14

Well categories used to be simpler but less fair. Even the complexity doesn’t eliminate the unfairness but hopefully produces groups with a tighter range of ability. Here on the forum you can find people who basically live down the rabbit hole of how that stuff works. But there’s no requirement to be some kind of deviant who thinks about racing categories all the time - you can also just do the races, and hopefully enjoy them.

15

I did enjoy it, and thanks for the explanations. I only enter the occasional race event because I like the challenge.

It just bugs me when the description of the event doesn’t match how it actually works.

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16

Categorisation is pointless for iTTs imho. The only place they make sense is where the TT is part of a series (as categorisation DOES make sense in scratch/points races).

What does it matter if you win your category? If its w/kg it just means you’re heavy, and if its ZRS it means you’ve not done many races or are a poor scratch racer…

17

Dopamine.

I’d rather the default for every event was a mass start with a filter at the end for velo/age. There is always someone faster than you, and that is ok. If race attendance was getting too large start splitting, but most of the time it’s 1-10 people per cat.

18

Personally for TT’s I like the one-at-a-time intervals.

19

Sorry yes. Run it as an interval start TT but also only have 1 pen you can filter. It’s weird to see Cs beating Bs and so on

21

That would be me