Isaac Boson: geometry and sizes
Isaac may sell more than one frame under the Boson name, each with its own geometry. These are the ones in the database. Each shows stack and reach for the smallest and largest size. The numbers for every size are on the model page.
The tables show the smallest and largest size, each with stack / reach in millimetres. Both terms are explained in the glossary.
Current Isaac Boson versions
| Version | Smallest | Largest |
|---|---|---|
| Boson 2026 endurance road · carbon | S · 538.5 / 368.3 | XXL · 614.4 / 419.6 |
| Boson RS 2027 road · carbon | XXS · 500 / 366 | XXL · 612 / 402 |
The same size label on two versions doesn’t mean the same frame. And stack and reach only describe the frame: where the bars end up also depends on the stem, spacers and bars.
There’s no sizing by height here. Everything starts from your position. Enter your position and I’ll work out which versions and sizes match it.