Good to know: Integrated cockpit · Configurable build
Integrated cockpit (a one-piece bar and stem) on at least one build. Changing the length means replacing the whole cockpit, and not every length exists. Check which length the bike actually ships with before you buy.
Configurable build (at least partly: the cockpit or bar width, for example). The stock build below is only one of the options.
Geometry ?
Isaac Boson 2026 geometry in sizes S–XXL: stack 538.5–614.4 mm, reach 368.3–419.6 mm, head angle 71–73.5°.
| S | M | L | XL | XXL | |
|---|---|---|---|---|---|
| Stack | 538.5 mm | 564.8 mm | 576.7 mm | 590.5 mm | 614.4 mm |
| Reach | 368.3 mm | 389.5 mm | 398.9 mm | 402.1 mm | 419.6 mm |
| Head angle | 71° | 73° | 73° | 73.5° | 73.5° |
| Seat angle | 75° | 74° | 74° | 73.5° | 73.5° |
| Seat tube (c-t) | 455 mm | 496 mm | 526 mm | 539 mm | 565 mm |
| Head tube | 142.4 mm | 160.2 mm | 172.6 mm | 185.2 mm | 210.1 mm |
| Top tube (effective) | 512.6 mm | 551.5 mm | 564.3 mm | 577 mm | 601.6 mm |
| BB drop | 70 mm | 70 mm | 70 mm | 70 mm | 70 mm |
| Chainstay | 410 mm | 410 mm | 410 mm | 410 mm | 410 mm |
| Wheelbase | 986.5 mm | 991.8 mm | 1004.9 mm | 1007.2 mm | 1031.8 mm |
| Standover | 755.5 mm | 788.8 mm | 809.1 mm | 822.8 mm | 846.8 mm |
| Fork length | 371 mm | 371 mm | 371 mm | 371 mm | 371 mm |
| Fork offset | 50 mm | 45 mm | 45 mm | 45 mm | 45 mm |
Source: isaac-cycle.cz, checked 2 Nov 2026 · bar position: worked out from published data
Older model years in the archive with the same stack, reach and head angle: 2022–2025. Source: web.archive.org
Stock build
Boson Shimano 105 ≈ €3,450
- Groupset
- Shimano 105 2×12
- Shifters
- Shimano 105 ST-R7120
- Cranks
- Shimano 105 50/34 172.5 mm stock
- Stem
- integrated
- Handlebar
- ISAAC Airflow Carbon
- List price
- 86,240 CZK (isaac-cycle.cz, 2 Nov 2026)
Boson Shimano 105 Di2 ≈ €4,852
- Groupset
- Shimano 105 Di2 2×12
- Shifters
- Shimano 105 Di2 ST-R7170
- Cranks
- 50/34 172.5 mm stock
- Stem
- integrated
- Handlebar
- ISAAC Airflow Carbon
- List price
- 121,290 CZK (isaac-cycle.cz, 2 Nov 2026)
Boson Shimano Ultegra Di2 ≈ €5,652
- Groupset
- Shimano Ultegra Di2 2×12
- Shifters
- Shimano Ultegra Di2 ST-R8170
- Cranks
- 50/34 172.5 mm stock
- Stem
- integrated
- Handlebar
- ISAAC Airflow Carbon
- List price
- 141,290 CZK (isaac-cycle.cz, 2 Nov 2026)
Options when ordering (manufacturer’s default in bold):
| Size | Stem | Bar width |
|---|---|---|
| all | 90, 100, 110, 120 mm | 380, 400, 420 mm |
Source for all builds: isaac-cycle.cz, checked 2 Nov 2026
Frames with similar geometry
Stack and reach within 12 mm of size S (stack 538.5 / reach 368.3 mm).
Stack and reach within 12 mm of size M (stack 564.8 / reach 389.5 mm).
Stack and reach within 12 mm of size L (stack 576.7 / reach 398.9 mm).
Stack and reach within 12 mm of size XL (stack 590.5 / reach 402.1 mm).
Stack and reach within 12 mm of size XXL (stack 614.4 / reach 419.6 mm).
Spotted a mistake or a missing build? Let me know.
Are you the manufacturer, or do you sell this bike? I’m missing 6 values for this model’s stem and bars. Add them