Inunaki Pass

Overview

Inunaki Pass is a Category 3 climb in Japan, running 10.6 km from a low, near-sea-level start to a modest summit. It begins at 25 m of elevation and tops out at 361 m, for a net elevation gain of 336 m. On paper those numbers read as an easy day: a long, gentle drag with a shallow average gradient and no alpine altitude to contend with.

The paper version is misleading. The net gain is 336 m, but the total ascent is 705 m — a gap of 369 m of climbing that the elevation profile hands back on the way up. That mismatch is the signature of an undulating road: you are not climbing one smooth ramp, you are climbing, descending, and climbing again. Your legs pay for all 705 m even though you only end up 336 m higher than you started, so the effort is meaningfully harder than the average gradient suggests.

How the Gradient Unfolds

The 3.18% average is an accounting figure, not a riding experience. Averaged across descents and false flats, it flattens out the parts that actually hurt. The real story is in the spread between that 3.18% mean and the 23.7% maximum pitch.

• Flatter and recovery sections, including short descents, that drag the average down.
• Repeated short climbs stacked back to back — the reason total ascent runs to 705 m.
• A steepest ramp reaching 23.7%, far beyond anything the average prepares you for.

Pacing Notes

On a smooth climb you can pace to even effort and let speed vary. Inunaki Pass rewards the opposite discipline: chasing even speed here will spike your effort on every steep ramp and waste energy hammering the descents. Pace to even effort instead, holding a steady sustainable power output through the pitches and easing back — even soft-pedalling — on the downhills where speed is nearly free.

The 23.7% ramp will briefly force you well above that target no matter how disciplined you are; accept the spike, then settle back. If you do not know your ceiling, run the numbers through the FTP estimator before you commit to a pacing plan.

Gearing

The average is irrelevant to gear choice — the 23.7% maximum governs it. At that grade you want a compact or sub-compact chainset paired with a wide-range cassette. A 34×32 will get most riders over it; a 34×34 gives you margin for the ramp with tired legs late in the effort. Check your setup before the ride. Confirming your smallest gear at home is far better than discovering it is too tall halfway up a 23.7% pitch.

Summary

• Length: 10.6 km
• Average gradient: 3.18%
• Maximum gradient: 23.7%
• Net elevation gain: 336 m
• Total ascent: 705 m
• Category: 3

Read Inunaki Pass by its total ascent, not its average. The 705 m of climbing and the 23.7% ramp are what you should plan around — pace to effort, gear low, and the gentle average will look after itself.