if you think about sitting on a bike, or a bicycle in this example, basically, you don’t really have any tools to help hold you up except, you know, shifting your weight, and then of course you can change the location of where you turn the handlebars and so as you turn the handlebar, that’s the exact same tool that Honda is using in order to help their bikes stay upright. Now, in order to understand how this technology works, we need to talk about trail length. So, there’s two different trail lengths we’re going to be talking about: positive trail length, and this is where the steering axis on the bike lies ahead of where the center of the tire is, and this is good for sporty riding, this is good for pretty much any riding at speed and then there’s something called negative trail length, and this is where the steering axis will lie behind the center of the tire and so this is good for super low speeds to maintain stability and so what these do is change how the bike moves when you pivot that steering axis and so if you turn to the right with positive trail length if you turn that bike to the right it’s going to want to turn into that, and fall into that corner.
If you turn a negative trail length bike so you’re sitting on a bike like this, you turn the wheel like that it’s going to want to push you out this way and so to understand how that works, we’re looking down on top of the tire. So there’s our center point that’s actually touching the ground, and if you have positive trail length, that means your pivot point is going to be up here, so if you were to pivot up here, that’s going to want to push that center this whole tire this direction, and so, obviously, if you’re pushing the tire out that direction, it’s going to want to make your bike fall over this way. So you turn the bike in, it pushes the bike it pushes the tire that direction and you fall over.
The other side with negative trail length, if you have that center there, you’re pivoting the tire this direction, so you’re going to try to turn it like that. You’re going to try to push the tire that way, rather than, like, this way and so that’s going to push your bike, of course, that way and so if you’re starting to fall over this direction, and you turn the bike in you turn those handles in you’re going to push yourself back up. So a very simple demonstration here using a coaster and a sheet of paper. You can see that if we have positive trail length, so the pivot point is ahead of the center of the tire. If I rotate that, it’s going to move the sheet of paper to the left. If we have negative trail length, so the pivot point is behind the center of the tire and you rotate it, you’re going to move the sheet of paper to the right. So this is what Honda’s actually doing with their bike. So they’ve got a simple setup. Here, you’ve got a variable sight angle system, which extends the front of the bike out. You’ve got a steer by wire system for low speeds and you’ve got the steering motor so that the computer can take over control. So the process is very simple.
At low speeds, your handlebars are going to disconnect from the steering and a computer is going to take over and do those minute adjustments for you. So if the bike starts to tilt, it simply turns that wheel into that direction that the bike starts to fall, and it maintains the bike upright, so that it doesn’t fall over. Now, this is a pretty cool technology and I can almost already read the comments of people saying, you know, “this is for people who have no idea what they’re doing,” but I can certainly think of scenarios you know, if you’re older, if you’re shorter, or if you just have a really heavy bike and you still want to ride and, you know, these things are working against you, there are certainly scenarios in which this can be beneficial and help make it easier for people. When you’re standing there at a stop light or, you know, crawling at slow speeds in traffic and you don’t want to worry about putting your foot down or things like that. You know, depending on if you’re older, shorter, etc., how heavy the bike is… So I can certainly see the benefit of a system like this and it is really cool how simple the system is.