Gravel bike geometry 101: How trail, stack and reach affect fit and handling

If you’re shopping for a new bike right now — or have bought one in the past decade or so — you’ve probably noticed that in addition to listing things like the build spec and features, the manufacturer’s product page includes an extensive table that looks like some sort of spreadsheet nightmare.

Never fear, though: those numbers don’t discuss budgets or forecasting or TPS reports. More commonly referred to as a geometry chart, they detail the critical dimensions of every size in which that bike is offered. But what do all of those numbers mean? Most people won’t need to concern themselves with every line item, but it helps to understand the basics.

First and foremost, it’s important to separate all of those numbers into two main categories. Some of those numbers will describe how the bike will fit in relation to your body, which will have all sorts of implications in terms of how comfortable you’ll be. The other numbers will help describe how the bike handles: how stable it feels at speed, how agile it is through corners, how planted it feels, and so on.

This isn’t meant to be an exhaustive treatise on frame geometry, but if you’re not already acquainted, hopefully you’ll find this primer useful.

Our Field Test group bike tests are by no means paid events, but they’re still only possible with some outside support.

CyclingTips would like to thank the following sponsors for this round of the Field Test:

Rudy Project
https://rudyproject.com/

Pearl Izumi
https://pearlizumi.com/

Sierra Nevada Brewing Company
https://sierranevada.com/

Lead Out Gear
https://leadoutgear.com/

Park Tool
https://parktool.com/