Esker JaphyGeometry & Bikepacking Bag Fit2026
Esker Japhy frame geometry, drawn to scale
Every tube angle and length below is from the published chart, not an illustration. The front triangle area is the number that decides which frame bags fit — and it changes a lot across sizes.
What it can carry
Mount provision and clearance, as Esker publishes it.
Geometry
All figures in millimetres except angles. Effective top tube and seat tube are the two that decide frame bag fit.
| Size | Eff. top tube | Seat tube | Standover | Head tube | Stack | Reach | Chainstay | Wheelbase | BB drop | Head angle | Seat angle |
|---|---|---|---|---|---|---|---|---|---|---|---|
| S1/SM | 570 | 375 | — | 95 | 600 | 420 | 430-444 | 1130 | 65 | 66° | 76° |
| S2/MD | 611 | 410 | — | 105 | 610 | 450 | 430-444 | 1164 | 65 | 66° | 76° |
| S3/LG | 634 | 440 | — | 125 | 625 | 470 | 430-444 | 1192 | 65 | 66° | 76° |
| S4/XL | 660 | 475 | — | 145 | 645 | 500 | 430-444 | 1231 | 65 | 66° | 76° |
Bottom bracket height
Roughly 310mm off the ground. Eskerdoesn't publish this directly — we derive it from their BB drop and a typical 75cm tyre diameter, so treat it as indicative rather than exact. It changes with the tyre you fit. Lower means more stable and more pedal strikes; higher means the opposite.
Source — Esker's own geometry chart: https://eskercycles.com/en-de/products/2026-japhy — checked 2026-08-16. A dash means the figure isn't published; we leave it blank rather than estimate.
Which frame bags fit
Every frame bag we track, checked against this frame's published geometry. Pick your size.
Checking 12 frame bags against a 634mm effective top tube and 440mm seat tube. 12 fit.
Read these as conservative. This size has a steeply sloping top tube — the seat tube is only 69% of the effective top tube. Bag makers publish a minimum seat tube length assuming a roughly level top tube, so on a frame like this the comparison understates how much room you actually have. The front triangle here is about 1336 cm², which is the number that actually decides what fits. Several bags marked unlikely below will physically fit. Half-frame bags don't depend on seat tube length at all.
Frame bag fit is calculated from Esker's published geometry, so it's as reliable as their chart. Seat packs and handlebar rolls depend on your exposed seatpost and bar width, which no geometry table lists — the bag finder covers those once you add your own measurements.