Questions
How accurate are the watt figures?
Treat them as a guide to what to spend money on first, not as a measurement of your exact setup. Most data come from published wind tunnel testing, and where a figure is our own estimate the tool says so and gives it a low confidence score. Hover the ⓘ on any row to see which.
Nothing has been checked against riders with measured drag data. The ranking is more trustworthy than the exact watt figures.
My tyre isn’t in the list.
Tyres are grouped into five speed tiers rather than listed by model, so you pick the tier that best fits and get a figure based on real rolling resistance data for the tyres in that group. If you don’t know what you’re running, choose “I don’t know” and it assumes tier 4, which is where most bikes ship.
Why is there no watt figure on the position advice?
Our position advisor is in Beta testing. For now you can get some high level recommendations based on what the tool observes, and some of our kit suggestions will help improve your position (e.g. praying mantis aero extensions).
If you want proper position advice get a bike fit, or join the “Time Trial Positions” Facebook group for a roasting.
What happens to my photo?
It goes to our server and then to an AI vision model that works out what bike and kit you’re running. The vision model is run by Anthropic. Their handling of data sent to their API is governed by their own terms. The position read happens in your browser, so your photo isn’t sent anywhere for that part. More on the privacy page.
It got my setup wrong.
This is the reason we have the verification step. Sometimes, often due to photo resolution, the tool struggles to see the difference between some equipment categories (for example helmet types, jersey vs skinsuit, socks vs aero socks).
What speed should I put in?
Your realistic average for the event you’re training for, not your best ever. Speed changes the ranking, because aero savings grow quickly with speed while rolling resistance savings don’t. At 32 km/h tyres and chain matter relatively more. At 45 km/h the aero items pull ahead.
Why does it suggest a cheap thing above an expensive one?
The list is ranked by watts per pound, not watts. A disc wheel saves more than waxing your chain, and it costs about fifty times as much. The ranking answers “what should I do with the next £50”, which is usually the more useful question. The watt column is there if you’d rather sort it in your head.