The Mountain Bike Geometry Revolution.
In ten years, mountain bike geometry has transformed beyond recognition. Longer, lower, and slacker changed everything — and the changes are still accelerating.
Published
2024-10-17
Read time
6 min read
Where It Started
A decade ago, the benchmark trail bike had a 67-degree head tube angle, a 430mm chainstay, and a 430mm reach for a medium frame. Today’s equivalent sits at 64 degrees, 435mm chainstay, and 470mm reach. Those numbers seem incremental. The ride difference is transformative.
The slack head angle moves the front wheel further forward relative to the rider. Combined with a longer reach, this keeps the rider centred over the bike on steep descents rather than pitching them over the bars. The physics are straightforward. The practical effect — the ability to point a bike at a steep technical line and actually commit to it — changed what mountain biking felt like.
The Mullet Debate
The most recent geometry development is the mixed-wheel setup: a 29-inch front wheel paired with a 27.5-inch rear. Proponents argue it combines the rollover advantage of the larger front wheel with the agility and clearance benefits of the smaller rear. Critics argue it’s a compromise that optimises for nothing.
The data from professional enduro racing — where every second matters and riders are on the most technically demanding terrain in the sport — increasingly favours the mullet setup. It is difficult to argue with results.
What This Means for Our Bikes
The Summit X9, Full Send, and Enduro X were all designed around current geometry thinking. Slack angles, long front centres, short stems, wide bars. The geometry does the work that technique used to have to compensate for.
It also means that riders who haven’t updated their mountain bike in five years are riding a fundamentally different experience to what the sport now offers. The upgrade gap in mountain biking has never been wider — or more worth closing.