Bike fit + sizing (Retul, Gebiomized, BodyGeometry), how do you recommend the right frame size online?

Bike-fit recommendation cuts return-for-fit rate ~22% on full-build bikes. The customer enters body measurements and the PDP shows which frame size in the family fits best, with a sizing-confidence indicator (high/medium/low).

Magento setup:

• Sizing calculator on PDP, customer enters height, inseam, torso length, arm length. Optional: shoulder width for women’s-specific geometry, riding style (race / endurance / gravel).
• JSON fit-table per frame family, stack/reach numbers for each size, recommended saddle-to-bar drop, recommended stem length range. Maintained by your bike-fit team or sourced from the brand’s geometry chart.
• Recommendation engine, Alpine.js calculator picks the size where the customer’s stack/reach lands closest to the “ideal” for their riding style. Returns a primary recommendation + adjacent fallback.
• Deeplink to LBS for a professional fit, if confidence is medium/low, page nudges customer to book a Retul / Gebiomized fit at a nearby dealer. Integrates with the LBS network locator.

Cost: $4k, $10k for the calculator + JSON fit-table per frame family. Maintenance: ~$500 per new frame model added. Some brands embed Retul or BodyGeometry APIs directly, enterprise pricing only (~$2k+/mo).