The Bike Size Decision Kit
The BlastCycle kit for turning two frame-size answers into one bike that fits, before you pay for it
The Bike Frame Size Calculator gives two answers at once: a size range from a height chart and a single size from the inseam formula. It never says what to do when they disagree, and they can. A 180 cm rider with an 83 cm inseam gets L, 56 to 58 cm, from the chart and 55.2 cm, an M, from the formula, because the chart's L band quietly assumes an inseam of 84.2 to 87.2 cm. The Bike Size Decision Kit is what to do between the calculator and the test ride. Part 1 turns the two answers into one window (55.2 to 56 cm for that rider), lets standover set the ceiling (an example 58 leaves only 2.0 cm and is out), and compares reach and stack rather than the number on the frame. Part 2 checks the easiest gear at your climbing speed with the site's gear ratio, speed and chain length tools, prices the grams with system W/kg (for a 75 kg rider, a kilogram off a 9.5 kg bike saves at most 14 seconds on a 20-minute climb), and sets the saddle before a test ride that means something. Worked figures and bike geometry are examples, and rules of thumb are named as such. It is general sizing guidance, not a professional fit, and says nothing about calories, diet or body weight. Includes a measurement sheet, a shortlist comparison, a test-ride scorecard, every chart's hidden inseam, and a personalised sheet worked on your own numbers.
Look inside
Two full pages from the kit, exactly as printed. Click either to read it at full size before you decide.
What is in it
- Measuring your inseam so the answer does not move
- Turning the height-chart and inseam answers into one window
- Standover as the ceiling: the size that is out whatever the chart says
- Reach and stack: why a 54 can fit like a 56
- The easiest gear at your climbing speed, and a bigger cog done safely
- Pricing the grams: what a lighter bike can save on a climb
- A test ride with the saddle set and the brakes learned
- A measurement sheet, a shortlist comparison and a test-ride scorecard
- Every chart's hidden inseam for road, mountain and hybrid, and a quickstart
- A personalised sheet: your size window, standover limit, saddle height, gear and grams
- ✓ 23 printable pages
- ✓ 10 sections, worksheets and templates
- ✓ A second PDF worked out from the numbers you enter
- ✓ No account needed, just an email address
- ✓ Instant download; link valid 7 days
Price includes any taxes. Sold by GrabURL, who handle checkout and support. The charge appears on your statement as GrabURL.
The kit picks up where the free Bike Frame Size Calculator leaves off. The calculator gives a height-chart size and an inseam size; the kit turns the two into one window, then checks standover, reach and stack, gearing and bike weight with the free gear ratio, speed, chain length and power-to-weight tools. General sizing guidance, not a professional bike fit.