A quick tour of each tool — what it's for, what the controls do, and how to read what comes back.
I built PolkaDOTBike as a handful of small tools I actually wanted for my own riding: work out a gear, plan a climb, sanity-check a groupset before I spent money on it. None of them needs a manual — but a couple of useful touches are easy to miss, so here's the thirty-second tour of each.
Two things are worth knowing up front. Your bike setup follows you from one tool to the next, so you only enter it once. And any result can be turned into a link you can share. More on both at the bottom.
Pick your bike, and it lays out the whole range slowest-to-fastest so you can see your spread at a glance.
The chart shows every gear in one of three modes — m/rev (metres rolled per pedal stroke), speed at your chosen cadence, or gear inches. Overlapping gears that cross-chain are flagged so you can see them.
It also colour-codes the step — the size of the jump between one gear and the next — shown both as a percentage in the gear list and as shading on the chart: green for a seamless step under 10%, amber from 10–14%, and red for a wide jump of 14% or more. It's the quickest way to see where your gearing eases between gears and where it makes you lurch.
Set your real cadence before you read the speeds — the same gear reads very differently at 80 rpm and 100.
Tell it the climb and your numbers, and it solves for your speed using real physics: gravity, rolling resistance and air drag.
If you only know your weight roughly, round up — kit and bottles add more than people expect, and weight is what the gradient charges you for.
Build System A and System B — either one can be a stock groupset or a Custom setup you type in yourself: name it, set the chainrings, list the cassette cogs. Leave the small ring blank and it's treated as a 1×. Both are drawn on one chart, A in its brand colour, B in dashed white, and you can flip the whole thing between metres of development, speed and gear inches.
The clever bit is the heat strips above and below the chart. They don't show the gaps between gears — they score how closely the two systems match at each point of the range, green where they're within 4% of each other through to red where they're 15% or more apart. Two 2× setups get two strips: big rings compared along the top, small rings along the bottom. Put a 1× against a 2× and the single ring is scored against both of the other bike's rings, one strip each. Two 1× bikes need just the one.
A strip that runs green end to end is telling you something the price tags won't: you'd be buying the same gears with a different badge. It's the orange and red stretches — usually at the very top or very bottom — that show where one setup genuinely does something the other can't. (If the jargon trips you up, the glossary explains it.)
Every rear derailleur can only take up so much chain. This works out whether yours can cope with the range you want.
It adds up your total capacity — (big ring − small ring) + (big sprocket − small sprocket) — and tells you whether that's within the derailleur's rating or exceeds it.
If it exceeds capacity, the chain goes slack in your easiest gears. Worth checking before the new cassette arrives, not after.
Enter your power and your weight and it gives you watts per kilo — the figure that actually decides how you'll go uphill — and shows where you sit against the standard tables.
The result is your W/kg and a category placing, from Cat 5 up to World / Pro level, based on the Coggan power-profile tables.
Both halves count: dropping a kilo can move you up the table as surely as finding a few more watts.
Browse the race stage by stage. During the race itself the list jumps to the day's stage automatically (and handles rest days); the rest of the year it opens on the start.
Each climb card gives you its length, average gradient, category and an elevation profile. The Plan this climb → button on a card sends that climb's distance and gradient straight into the Climb Planner — pre-filled with the setup you've already chosen — so you can see what it'll take for you.
Choose your groupset and wheels once on the Gear Calculator and they carry across to the Climb Planner, the Comparator and the race climb browsers. You're not re-entering your bike on every page — change it anywhere and the other tools pick it up.
The Copy link button packs your exact setup into the page address. Send that link and the other person opens the precise gear chart, comparison or climb you were looking at — nothing to re-key. Handy for asking "is this enough gear?" without a paragraph of explanation.
On the Gear Calculator, Climb Planner and Comparator, the ⎙ Report button opens a clean, branded summary of your setup and results that you can print or save as a PDF — handy for taking to the bike shop, or keeping a record of a setup before you change it.
And if any word on the site is new to you — gear inches, CdA, capacity, VAM — it's explained in the Glossary.