Welcome to another post in our series aimed at helping you avoid n00b powerup mistakes in Zwift races.
Powerups add a fun element of randomness and strategy to Zwift racing. While some purists deride their use, most racers welcome their addition to an indoor racing experience which can feel a bit oversimplified since it has fewer variables than outdoor riding.
Experienced Zwift racers understand how powerups work, but we see them used incorrectly over and over again. Hopefully this series can help.
Still learning? Read our “Guide to Powerups in Zwift” >

The Anvil: How It Works

As you might guess, the Anvil powerup makes you heavier when activated. Specifically, it makes you 50 kilograms heavier for 30 seconds. But crucially, that 50kg is only added while you’re on a descent of -1.5% or greater.
(The Anvil didn’t always work this way. Initially it simply made you 50kg heavier for 30 seconds, regardless of the terrain. But Zwift found many people were misusing it on flats or climbs, so they decided to make it smarter in September 2022.)
Why would any cyclist want to gain weight? Because it makes you faster on the descents! Activate this powerup on downhills – the steeper and longer the better – for a speed boost. Combine it with a supertuck for even more speed.
Here are two shots from a Zwift Insider Tiny Race where every rider received an Anvil… and most deployed it on the downhill lead-in to the sprint:


How It’s Misused
While its usage may seem obvious, many Zwifters aren’t familiar with the Anvil since it’s one of the newer powerups in game and only appears in events where organizers have specifically enabled it.
The most obvious misuse of the Anvil is on flat or uphill roads. Before the Anvil became “smart”, activating it on a climb could get you dropped from the pack quickly.
Now, with the 50kg only applying on descents, activating your Anvil on a flat or climb simply wastes it. Like activating your draft boost when you’re on a solo breakaway, it has no effect. You might as well just throw the powerup away.
Building Momentum
Racers have found that the smart Anvil is a potent weapon in certain situations. 50 kilograms is a lot of weight, and you’ll find yourself descending much more quickly with the Anvil activated.
Using it on long descents is a no-brainer, but it can also be used to build momentum on a short descent which can help you on the flat road or climb that follows. Activate the Anvil on the descent, give a good kick to reach a high speed, then keep pushing after the road levels out to maintain your speed. You’ll find that the momentum you built with the Anvil will carry you across flat ground and up small climbs much more quickly than if you’d attempted the same, sans Anvil.
Questions or Comments?
Share below!
I hadn’t realised that it was smart, so thanks for that, it’s handy to know.
“While some purists deride their use, most racers welcome their addition to an indoor racing experience…”
Do you have data to back that up? (The last part about most racers welcome their addition)
From my anecdotal experience it is not the case. Some sure but I would guess that a little over half the racers would prefer no power-ups.
And definitely a majority is against the randomness of it and would prefer it to be either fixed (same power-ups for all) or player/rider chosen.
Everyone I know thinks they add a bit of spice. That’s the great thing about anecdotal evidence 😉
I am probably wrong, but I recall reading something on here about the supertuck being slower than pedalling on the descent.
IIRC it’s only faster wihtin a race-event, in normal group-rides or free-rides it’s slower.
It’s faster in races, which are the only place you’ll see Anvil powerups generally speaking. More info: https://zwiftinsider.com/speed-tests-supertuck/
Just answered my pending question. I’ve never received an anvil – racing in the future 🙏
Depends how hard you pedal
Sometimes we just want to use up the PU when another is coming up…doesn’t always mean that the user don’t know how to use PU.
Hi, why do you think gaining weight “makes you faster on the descents!”? Can you explain the physics of how it happens? In real life heavier cyclists are slower going downhill due to their increased size and therefore increased aerodynamic drag.
This is a good demonstration of the interaction of mass, gravity and aerodynamic drag.
https://youtu.be/Oo8TaPVsn9Y
You may need to rethink this one.
Regards
Fortunately, John, we don’t ride in vacuums. 🙂 IRL experiences may differ, but generally I think cyclists would agree that heavier riders descend faster than lighter ones. That’s certainly been my experience. It’s because their weight is greater, and thus their terminal velocity is higher. Or to put it another way, “When you increase the mass the speed increases by cubic function, whereas if you increase the aerodynamic drag the speed decreases by a square function.” Yes, they may be a bit less aero, but if they’re staying in a good tuck they should be able to out-descend a lighter… Read more »
I’m a lightweight. All of my bigger friends go downhill faster than me. They’re coasting, and I’m having to pedal my butt off in their draft of I want to keep up. It’s physics. Their heavier weight enables them to cut through the air better.
You must never ride with other people to have it so wrong.
Oh dear oh dear.
Gravity is the same for both. As many experiments show in absence of air restance all objects will accelerate at the same rate. 9.8m/s2. We don’t live in a vacuum so air resistance I.e drag will have an effect. A heavier rider will have a higher terminal velocity as at the start of a descent they have more potential energy available to be turned into kinetic energy. Laws of conservation of energy.
Need to add that cda unlikely to increase linearly with increase in mass so potential energy increases at a greater rate than drag there increase in speed not just kinetic energy, which is of course also related to mass.