THE METHOD
The numbers, explained.
Start with a known frame. Compare exact sizes. Understand what differs.
What are frame stack and reach?
Stack is the vertical distance from the bottom bracket center to the top-center of the head tube. Reach is the horizontal distance between those points. Both describe the frame, rather than your final hand position.
How do you choose an alternative size?
Within every eligible frame family, GnR checks each published size and chooses the one closest to the search target. It ranks those families and shows the three closest. Road/gravel, type and archived-generation filters control eligibility.
Distance = √[(stack difference ÷ 15)² + (reach difference ÷ 10)²]. “Close” means a distance up to 1; “Some change” means above 1 and up to 2; “Large change” means above 2. These are initial comparison bands, not validated fit probabilities.
What does changing my position preference do?
- Similar frame: keep reference stack and reach.
- Higher, shorter frame: +15 mm stack and −5 mm reach.
- Lower, longer frame: −15 mm stack and +5 mm reach.
- Shorter reach: keep stack and subtract 10 mm reach.
These settings help explore alternatives. They do not prescribe a bike fit. Differences on cards remain relative to the original reference.
What is the Position label?
Position uses frame stack and reach only. GnR compares every size with one fixed benchmark for road and gravel alike. The benchmark was calibrated on October 17, 2026 from 19 current frame families and 119 sizes; each family received equal total weight so a frame with more published sizes did not count more heavily.
The benchmark predicts stack ÷ reach as 0.7541660754 + (0.00123929937 × stack in mm). A size more than 0.02 above that line is Relaxed (shorter frame reach at the same stack). A size more than 0.02 below it is Aggressive (longer frame reach at the same stack). Everything else is Balanced. Because the constants are frozen, changing a bike’s road/gravel category or adding frames to the catalog does not move existing labels.
A label describes the frame’s front-end proportions, not a rider or completed bicycle. Stem length and angle, headset spacers, handlebar reach and shape, control position, saddle height and setback, crank length and component adjustment all affect where your hands and saddle finish. The label cannot guarantee fit or comfort.
How are types assigned?
The five leaf categories are Road Race, Road Endurance, Gravel Race, Gravel All-rounder and Gravel Adventure. Road Race has exactly one focus: All-round, Aero or Lightweight. Road Endurance gets All-road when manufacturer-verified clearance is at least 35 mm; this is the Ryan/William house rule, not an industry standard. Drop-bar road bikes sold for all-road remain Road Endurance. Gravel takes no tags. Use maker wording first; where unclear, review geometry together with mounts, never clearance alone. Each model page preserves a separate maker excerpt and a dated classification source. Focus and category do not change the geometry-only Position label. See every type ↗
Where do prices come from?
Prices are the maker’s US list prices for complete bikes on the date shown, and include sale prices on that date. Ranges cover only the named builds, not every bike in a family. Framesets, tax and shipping are excluded. A displayed price, including an archived sale price, does not establish stock or a purchasable offer. Retailer prices and later changes are not tracked. Price is not part of the ranking.
What is outside the ranking?
Full cockpit setup, saddle position, handling, build specifications, tire clearance, weight and stock. GnR does not infer them from frame stack and reach. Similarity to a bike you have never ridden cannot confirm fit.