@S_A_Cestria_CC paid you for this post
2 Likes
But it does help heavier riders more as it 10% of your weight.
If you weigh 130kg you decrease by 13kg, 50kg only 5kg decrease.
1 Like
it used to be a flat figure of like 10 or 15kg. it was unbelievably OP for light riders. maybe a flat figure of 5kg might work, if we are operating on the dubious assumption that light people are supposed to be better at climbing and heavier people are supposed to better at, i dunno, sprinting. but that’s not really true.
the aero is ridiculous at my size, i don’t know if it’s because i’m light or because i’m short. my favourite powerup is the ghost, but if an aero is available i will just roll one and then not use any PUs til the finish line. even if it’s on the first segment of a 20 segment race
That’s not how it works a 10% reduction in weight leads to a 10% reduction in power.
So 10kg for the 100kg racer will be the same as the 5kg reduction for the 50kg racer.
do you mean increase in power. How do weight decrease result in a loss of power?
Say a 100kg rider doing 300w = 3wkg, then reduce weight by 10%, 90kg doing 300w = 3.33wkg
Say a 50kg rider doing 150w = 3wkg, then reduce weight by 10%, 45kg doing 150w = 3.33wkg
BUT we all know that on the flat the 300w rider will leave the 150w rider for dead.
Does the feather really need to benefit heavy riders more than light when all the other power-ups already benefit heavy riders with more watts than light riders with less watts that are equal on WKG
1 Like
I don’t understand what you are saying.
The feather is used on climbs . W/kg is not relative on a flat road then pure power is the driving force.
Your math above shows that that the feather gives the same w/kg benefit to both heavy and light riders.
you’ve only half quoted me
I said
I am saying that the feather does help a heavy rider on a climb already, yes if a light and a heavy rider uses them at the same time then they cancel each other out, but that’s not relevant, it’s about the benefit of a PU - I don’t think the feather should be scaled to offer and even greater advantage as weight of rider gets higher.
We know that pure watts is the driver on the flat so all other PU used on the flat have a greater advantage to riders with pure watts (heavier riders) so heavy riders don’t also need the feather to be more powerful for them when climbing.
This is what I don’t get is how is it scaled to give heavy riders even greater advantage? Your math showed that it is an equal outcome.
This is also not correct Weight does not = power. same as light weight does not equal good climber.
I was replying to Tom who suggested that heavy riders should get a bigger % reduction
As a generalisation it’s fairly accurate to D and C zwifters and some B who are the majority of Zwift users that PU changes will effect though.
No, it helps all riders at the same rate. Same rate = equal help.
Look imagine a 50 pound rider, and a 500 pound rider. Now imagine you had a Feather that took 10 pounds off of each rider’s weight. Do you think that going from 500 to 490 is the same benefit as going from 50 to 40? That’s now how physics works.
Imagine a 200 pound rider, and a 500 pound rider, and a Feather that took 200 pounds off. Now you’ve got a 300 pound rider, and a 0 pound rider. Has that helped them both the same? 
Same rate = same benefit. 10% to all riders will take off different weight, but give the same benefit. (And I’m suggesting that the Feather and Aero change the rate of benefit.)
I have no idea why you are explaining it to me when it currently reduces the riders weight by 10%
All I’ve said is that 10% is fair and it should not be a higher % for heavier riders.
I’ve not said that it reduces a riders weight by a set weight.
I’m well aware of how % work 
What you said was
You have no idea why I said what I said because you’re not following the discussion.
- I said “the feather should help heavier riders more.”
- You said “But it does help heavier riders more” at it’s current setting (rate-based, percentage)
I am saying it does not help heavy riders ‘more’, because ‘help’ in this case is defined by the rate of reduction. How many facepalm emojis should I use at this point to express how badly you are missing the point? Do facepalm emojis help the discussion?
I was not explaining the rate-based system to you. I was explaining to you why you are incorrect in saying that the rate-based system “does help heavier riders more.”
The feather, by reducing everyone at the same rate, helps everyone equally. Thus, you are incorrect when you say “But it does help heavier riders more”.
If you were correct–that a rate-based system helps heavier riders more by taking off more total weight, then helping riders ‘equally’ would be taking off a set amount, not a rate. If you were correct, then a power-up that took off “X kg” from everyone would help them equally (i.e. would not help some ‘more’ than others). I am trying to demonstrate to you why this is mistaken. Helping all riders by a set number would not help them all equally, no matter what that number is. Taking 10 kg off a 50kg rider is far more help than taking 10kg off a 100kg rider. Taking 10% off a 50kg rider and taking 10% off a 100kg rider is helping them equally. It is not helping the heavier rider more.
I absolutely agree with you that a 10% saving in body weight is an equal %age saving no matter what your starting body weight.
As, I think, you have defined it - ‘help’ (with weight) is defined as the rate of reduction (of weight).
If I’m in a bike race speed is probably quite an important issue. I might wish to define ‘help’ (with speed) as the rate of increase (of speed)
A 100kg rider and a 50kg rider are both racing up a hill at exactly matching speeds (clearly not matching powers).
If suddenly both of them are able to shed exactly 10% of weight but maintain the same power what will be the affect on their bike speed?
So using the linked page, I threw in the following data:
Rider A: 100kg + 10kg bike, 5% gradient
Rider B: 150kg + 10kg bike, 5% gradient
I kept all other data the same (frontal area, drag, drivetrain loss, headwind, rolling resistance, air density).
Rider A: to do 20kph, output needed is 370 watts
Rider B: to do 20kph, output needed is 523 watts
I then reduced each rider weight (but not bike weight) by 10%.
Rider A (now weighing 90kg): @370 watts, speed is 21.45kph
Rider B (now weighing 135kg): @523 watts, speed is 21.76kph
0.3 kph difference
That slight difference in speeds after adjusting weight gets even smaller (<0.1 kph) when you reduce bike weight to 0. (Note that there’s some small error, given that it’s just hard to zero in on that graph to exact speeds due to mouse tolerances, so the '20’kph might be 20.01 on the web page.)
Now we can try reducing the weights by the same static number.
Rider A: 100kg+10kg, 370 watts @20kph
Rider B: 150kg+10kg, 523 watts @20kph
Now reduce each rider by 20kgs.
Rider A: 80kg+10kg = 23kph@370 watts
Rider B: 130kg+10kg = 22.25kph@523 watts
0.75kph difference.
You put that together very quickly.
I agree with your findings for %age body weight. Reducing both riders by same percentage results in the heavier rider going uphill just a little quicker.
So if I am most interested in the change of bike speed I would have to say a matching %age reduction in body weight slightly helps the heavier rider achieve a faster speed.
As you have shown changing weight by static numbers will have a different outcome, going uphill.
However I have also just looked at the Anvil - my first thought adding 50kg to everyone must surely help the lightweight rider. I’m not sure it does and I fear heavier rider gets the speed benefit once again?
Like you I am keeping other data variables the same.
Well, I am at work. I do non-work things much more efficiently when I’m supposed to be working 
5 Likes
Looks like adding 50kg gets this:
Rider A now at 150kg and 370 watts: 14.58kph
Rider B now at 200kg and 523 watts: 15.8kph
So yeah, that flat addition of the anvil kills the lighter rider.
My poor construction of a sentence. I meant using an Anvil on a downhill.
Doh, of course No, that’s my being in a hurry, not your mistake. Obviously hammering yourself with extra weight uphill would be bad 
I was thinking about this as well.
How can we use a persentage with the anvil as well.