Bike Tools and Calculators

Small, fast calculators for jobs that are easy to get wrong and expensive to redo. Everything runs in your browser — nothing to install, nothing to sign up for, and no numbers leave your phone.

  • Bike Tyre Pressure Calculator

    Front and rear psi or bar from your weight, measured tyre width, surface and setup. Covers road, gravel, MTB, e-bike and fat, with the hookless limit built in.

    RoadGravelMTBE-bikeTubeless

  • Bike Wheel Size Calculator

    Wheel diameter, circumference and the exact value to enter into a bike computer, plus a roll-out helper and a check on whatever is in your computer now.

    Bike computerCircumference700c29er

  • Spoke Length Calculator

    Left and right spoke lengths from your ERD, hub flange diameter and centre-to-flange. Shows what every cross pattern would give you, and draws the wheel as you type.

    Road & gravelMTBE-bike hub motorBMX

  • 2 Stroke Oil Mix Calculator

    Exact oil for any amount of petrol at 50:1, 40:1, 32:1, 25:1 or a ratio of your own, in millilitres or fluid ounces. Runs backwards from a part-used bottle too.

    2 strokeFuel mixingMix chart

More on the way. If there is a calculation you keep doing by hand in the workshop, tell us and it may well end up here.