Rake and Trail:

Rake and trail made easy: Rake is simply the angle formed by a line through the neck stem with a vertical line drawn to the ground when the bike is standing. It looks like this:

rake

As you know, choppers have a larger rake angle that most other motorbikes:

chopper rake

Rake And Trail Part 1:

A zero rake is when the neck points straight at the ground, and you never see it in a bike. You would have something impossible to handle - a clown's unicycle and a shopping cart both have zero rake. Generally, speaking machines with larger rakes will be great for stability and going in a straight line, but less good for tight maneuvers than those bikes with smaller rakes...

This is simply because increasing the rake moves the front wheel further away from the rest of the bike, increasing the overall length and therefore the turning circle. So a large rake usually means the bike is good for cruising on the highway. A sport bike may have a rake of 24 degrees, a cruiser 32 degrees, with ten to fifteen inches difference in their wheelbase dimensions. Each is designed for a different purpose.

Rake And Trail Part 1:

Trail is a relationship between the front wheel axis and the steering axis, measured as shown in the diagram below. It's measured in inches, and you can easily measure it yourself with a tape measure and a stick.

trail

Rake And Trail Part 1:

Most bikes have a trail between 2 and 4.5 inches. It can be altered by changing the neck rake, the fork length and type, triple trees, and the wheel diameter. This is not a hard a fast cut-off point and good bikes can be built with trails either side of the normal range, including a zero trail. If we go much larger than five inches or so we would get a bike that's really stable at speed, probably handling sluggishly, and which at low speed is going to be difficult to keep in line.

Rake And Trail Part 1:

It is possible to end up with negative trail (where the wheel axis is behind the steering axis) if you use some kind of extension at the bottom of the neck to force out the forks without doing any frame alterations - triple trees that do this are available. Everyone agrees that this is dangerous however, since the machine may handle in unpredictable ways at speed and on corners, which is never a good idea. Out of interest, it looks like this:

negative trail

Free Frame Building Mini Course:

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