There’s a standing segment on our Geek Warning podcast called “on your mind,” but it’s often a chance for the geeks to get something off their chests. This week I took the opportunity to offload a frustration that’s been bugging me.
When you look at a modern road bike geometry chart, you’ll usually see a list of measurements: stack, reach, wheelbase, head tube angle, chain stay length, and bottom bracket drop. Some brands will include fork rake (also called offset), but one of the most important numbers is commonly missing: trail.
Trail is a key figure in understanding how a bike handles. It’s the number that largely (but not solely) dictates how a bike feels and how we sense its response to steering input, whether it’s twitchy and hyper-responsive or stable and composed. It seems like a key point of consideration when choosing a bike, yet most brands leave it out of their geometry charts. Why?
You can, and should, listen to the discussion on this week's episode. You should also subscribe on your podcast player of choice (iTunes | Spotify) so you don't miss any Geek Warning pods.
What is trail, and why does it matter?
Rob English has already detailed the ins and outs of trail in his geometry and handling deep dive as part of The Whys of Bike Tech series, in which he also explains ground versus mechanical trail. So, to briefly summarise, the trail is the horizontal distance between where the front wheel touches the ground and where an imaginary line drawn through the head tube would intersect the ground.
It’s essentially the amount the front wheel contact patch "trails" behind the steering axis, which is why it’s called trail.
The easiest way to visualise it is a shopping cart wheel. The caster mechanism on the wheel creates trail—it naturally falls into line when pushed forward. This same principle applies to a bike, just with more complexity.
The trail has a huge impact on how a bike steering feels:
- More trail = more stability. The bike resists steering inputs and is less likely to twitch at high speeds. This is great for descending at 80 km/h and riding no-hands.
- Less trail = quicker, more responsive handling. The bike reacts instantly to inputs, making it feel lively but potentially nervous. Sprint-focused race bikes often sit at the lower end of the spectrum.
Unlike stack and reach, which define fit, trail defines feel. And if you’re choosing between bikes, knowing the trail figure tells you more about how the bike will handle than the head tube angle alone.
But there is no right or wrong trail figure. There are pros and cons to any decision on trail, and different disciplines require vastly different trails built into the bikes we choose for them. Gravel bikes, for example, will typically see much higher trail figures than a road race bike, the greater trail offering more straight line stability, whereas a road racer may prefer the more agile handling lower trail in their race bike. And then there’s the nuance in it all, where bikes with equal trail figures can still feel quite different due to other factors, but I digress.
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