Is W/kg a good metric for group rides?

A fence that doesn’t do anything but being a visual guide, is not a functioning fence. Now it just a very annoying red color on the screen when you come close. There is no incentive for staying behind the fence, so it has now lost it’s power.

I wanted to be funny here but this won’t work in text.

Just the fact that people see the fence help them to notice that they are being pulled to the front. So we get less complaints that the pace is to high only to realize that they are going with the front pack.

So it “works” but not like it used to work. :thinking:

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Hi good point, however the W/KG is average for the ride, I am 57 kg and really suffer when the road tilts down and have to put out more power to keep up even in the draft of the group. On hills I can ease back a little and put out less power. I suspect zwift will be be adding more BOTS to do group rides with the power above the 1.5 and below 2.5 to accommodate the the issue.

No w/kg should be upper and lower limits not average. I don’t know why some ride leaders insist on average w/kg.

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It irks me, too.

Averages are meaningless, as one could perform max-power sprints, destroy even the largest of groups, and yet still claim to be “keeping to the average pace”.

At the very least, organisers should clearly state whether the pace is average or upper/lower limits, with approximate expected power (Watts) for the leader. Then riders know what to expect, where average pace rides could see the leader surging and chasing.

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I agree that ride descriptions should elaborate on what any provided wkg range is actually a range of.

  • A 1-2.5 wkg range by itself is a large range percentage-wise. So in these cases, I think it really needs to be spelled out. While avg w/kg can be meaningless, this range could be interpreted to mean that most of the time, the ride would likely hover at somewhere in the middle (eg. 1.8 wkg).

  • If a more limited range is provided - eg. 2-2.5 – this could be (could be more possibilities even than this), unless otherwise explained, either:

  1. the range wattage seen at any given time of the leaders who are outside the draft, and is expected low (seen for downhill gradients) or high (seen for uphill gradients); or
  2. the range is provided to reflect the possible ending point average wkg (margin of error) that the leader will have output when looking at the ride metrics after ride is completed.
  3. the range wattage at any given point during ride, of the blob that’s enjoying the draft (ie. where most riders will be). But, range for the blob could be:
    a) just the wkg to expect on flat ground, with the range provided for higher vs lower weight riders; or
    b) the range for the blob in a draft to cover gradient changes, but then this wouldn’t be covering individual rider weight variances.
  4. The range of average wkg that a given rider should expect to end up within after looking back at their completed ride’s metrics. The range is provided to cover different rider weights.
  5. The range of average wkg that a given rider should expect to end up at within after looking back at their completed ride’s metrics. The range is provided to cover general variability of ride leader’s output (margin of uncertainty).

Ride listings should be given the category (A thru E) based on highest level wkg that is typically expected and seen during the rides (excluding any of the course sprints where anyone can participate). If a good portion of the ride is much lower than this higher limit (eg. the race scheduled for the last 10 minutes), then you still use the higher wkg category but call it a recovery ride for that level. Alternatively, label your ride as fondo cat E and put in eg a 1-3.5 wkg range.

Regarding the OP’s main question, I’ve found the W/kg useful at my “entry level” ability.

It helped me find both the “ZHCC Feel Good Friday [E]” and the “RO4H Rookie Group Ride [E]” events this week, and the ride leaders/sweepers were excellent communicators and teachers.
These were my first group events, and I chose them after lurking the forums and reading about the challenges of events exceeding the listed pace.

Both groups host [D] level events, so I look forward to seeing if their pacing holds true.

One way to electrify the fence would be to have the drop counter roll backwards if a rider pulls past. Maybe the ride creator could select this from a menu when setting up the event, and tell the participants “the fence is live” in the description? I can see some encouragement/enforcement beneficial in the entry-level group rides.

This would encourage fliers to stick with the group (clearly stated in the event description), or simply drop out and find something faster to test themselves against.

The ZHCC group event had the fence drop out at the end, so that became “hammer time”.

Which was fun!

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So I was steered here to ask the question as to whether, if we don’t think avg speed is a good metric, why straight watts wouldn’t be better than wkg? Presupposing you’ll likely rarely know the ride leader’s weight, at least you’d have a wattage range to expect. From that, it’s obviously easy to convert to wkg for your own weight (which is as good as anything I suppose not knowing the ride leader’s weight). But a 60kg ride leader listing for a 1.5-2 wkg ride would instead just be posted as 90-120 watts. If a 90kg ride leader does a 1.5-2wkg ride it would instead be posted as a 135-180 watt ride. Either way, it would seem more helpful if for no other reason that you at least have a better idea of what to expect on flatter portions of the route.

No. Watts would just creates splits on anything other than flats.

The fence should be lethal. End the ride without saving after the counter has finished. Then people will stay away from it.

Even on flat, equal watts doesn’t mean equal speed, far from it.

If you don’t believe me, just try changing your in-game weight and see what happens.

Equal W/kg isn’t perfect but it is better by far than equal watts.

Preaching to the converted! Watts have a chance of staying together on the flats with draft/good leads but this is kind of pointless when wkg is sufficient.

But using the examples I put forth, in both cases you’d be told 1.5-2 wkg for the ride. There’s a good difference between the avg 105 watts in first example and the avg ~155 watts in the second example, but they’d both be equal wkg. Which datapoint would you rather know?
“60kg ride leader listing for a 1.5-2 wkg ride would instead just be posted as 90-120 watts. If a 90kg ride leader does a 1.5-2wkg ride it would instead be posted as a 135-180 watt ride.”

I find w/kg to be more accurate with effort and pacing than just watts. A 250lb rider will have to produce more watts to move at 20 mph than a 180lb rider. Were as far as I can tell, a 250lb. rider doing 2.0w/kg is traveling at the same rate as a 180lb at 2.0w/kg. Both doing different wattages, but traveling at the same speed.

You’re exactly right, but since the supposition is you never often know the “kg” portion that the ride leader is basing on, then knowing watts is better. If you are provided the watts, you can always divide those watts by your own weight if you really want to get an arbitrary w/kg – but it won’t tell you much.

I get what you are saying, but does the weight of the ride leader matter, if you are going into the ride already knowing what kind of w/kg you need to produce? Assuming you go in knowing what w/kg you are comfortable with or looking to ride that day. If the ride leader is advertising 4.5w/kg, it doesn’t matter their weight, I know I can’t ride at that. But if it’s 1-1.5w/kg, I know it’s basically a recovery day, regardless of the ride leaders weight. I think it still comes down to equal watts, doesn’t mean equal pacing, which is important in a group ride setting.

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How is knowing watts better? It’s clearly much worse if you want to ride at a similar speed. The W/kg for a 50 and 100kg rider going at (say) 38kph is much closer than their watts. Even on level ground.

If you are super-light or super-heavy then you should realise that your W/kg is likely to be a little higher or lower than the quoted figure, assuming the pack follows the guidance reasonably closely. But if everyone rode at (say) 200W then they would be riding at very different speeds.

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BestBikeSplit has these times for various weights/watts - you can see heavier riders always have a w/kg advantage whatever the gradient:
Tempus Fugit:
300w/200lbs/3.31w/kg - 25.54mins
149w/100lbs/3.29w/kg - 32:15mins
149w/200lbs/1.65w/kg - 33:42mins

Ven-Top:
300w/200lbs/3.31w/kg - 1:31.38hrs
149w/100lbs/3.27w/kg - 1:41.27hrs
149w/200lbs/1.65w/kg - 2:58.00hrs

Does BBS copy zwift physics where your weight is used to change your CdA quite substantially?

I think this is where the widespread myth comes from - many cycling physics simulators allow for the separate specification of weight and cross-sectional area, and changing weight alone makes very little difference to speed at a fixed power (on flat road). In zwift, they are directly linked. Zwift’s general approach seems reasonable to me but I know that others complain that the influence of height and weight is too great.

I don’t know how the modelling is done though would be interesting to see how well it fits in with what people experience.

Here’s similar from Bikecalculator for real life riding - no account for height/shape I assume:
Flat:
300w/100kg/8kg = 36.25kph
150w/50kg/8kg = 29.08kph
150w/100kg/8kg = 27.57kph

8%:
300w/100kg/8kg = 11.14kph
150w/50kg/8kg = 10.23kph
150w/100kg/8kg = 5.67kph