rake a trike

Technical information and Q&A applicable to all years and models of Goldwings
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rake a trike

Postby Cindy » Wed Sep 05, 2012 11:01 am

Morning everyone!

I am looking for information regarding raking an 1986 GL1200 Aspencade trike. DH keeps talking about how it will make trike turn easier but because I have never driven bike/trike, I can't comprehend what he is talking about. Previous ride on narrow winding country road I saw him leaning hard the sparks were flying but push/pull with everything I had and I crossed lanes and was heading for rock wall. If there had been a car in the other lane, I guess I would have been dead meat. I ran out of turn before I ran out of road, now if raking will help in better control, THAT I can understand.

I have compared my trike to another trike that driver said was raked and I can see the difference, but he couldn't tell me a whole lot or where to access info so I can ask the right questions. So anyone out there can point me in the right direction?


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Re: rake a trike

Postby WingAdmin » Wed Sep 05, 2012 11:51 am

When talking about rake, it means adjusting the angle of the front forks, in order to lengthen or shorten the trail. The trail is defined as the distance from the point directly below the wheel's axle, to the point on the road where a line extended from the steering axis would touch:

Rake and trail
Rake and trail

There is also caster, which is determined by the lateral distance of the axle from the steering pivot, but that's not typically adjustable on motorcycles.

The reason this is important because more trail typically adds more returnability and stiffness to the steering, and less trail makes the steering easier to turn, but has less returnability. Returnability is the amount of force the steering system has to return itself to center.

On touring bikes where the vast majority of the time you are going in a straight line, more trail is desirable, to make the bike solid and easy to ride. On sport bikes, where lots of fast turning is required, you want less trail, to lower the amount of force required to steer, and make the bike somewhat less stable.

When you trike a motorcycle, you are adding two wide, flat tires, with large contact patches. These contact patches (along with the resistance of the differential) resist turning, meaning it takes more steering force in order to convince the trike to turn. By increasing the rake angle (pushing the front wheel farther away from the bike), without changing the steering axis, the trail is reduced, which lessens the returnability - and more importantly, lessens the amount of force required to steer the vehicle.

You still are at the mercy of physics however - the front tire still has a tiny little contact patch. At higher speeds, at some point, you will exceed the lateral grip of your front tire, and the front end will skid sideways rather than turn the trike. A different rake angle will not help you at this point. The only solution to this problem is to put a flatter (or wider) tire on the front, to increase the size of the contact patch. You can also redistribute weight on the trike to try to get more force (and thereby adhesion) on the front tire. In an emergency, you can very slightly let up on the power, or even touch the brake, which will shift weight onto the front tire and give it more grip. This requires a great deal of practice beforehand however - too much weight shifting forward on a trike that is cornering at the limits of front wheel adhesion is also a good recipe for tipping the trike over. Better to straighten out the front wheel, grab some brake HARD to reduce speed, then re-attempt the cornering.

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Re: rake a trike

Postby redial » Thu Sep 06, 2012 3:35 am

Wow! That response is awesome. I have never had it explained so eloquently, and it makes it all clearer. Thanks.[/color]
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Re: rake a trike

Postby Ghostman » Thu Sep 06, 2012 7:19 am

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Re: rake a trike

Postby Dogsled » Mon Sep 10, 2012 10:46 am

Cindy here's a quote from you

I can't comprehend what he is talking about. Previous ride on narrow winding country road I saw him leaning hard the sparks were flying but push/pull with everything I had and I crossed lanes and was heading for rock wall.

Were you comparing a two wheel bike that is raked (since he was 'leaning hard' to a trike? I have built at least 10 trikes from scratch (not Wings) when I had my shop.
Wing Admin's explanation is correct for a technical answer. Here's one you may understand better. On a trike or 2 wheeler. Every degree you rake and/or inch you extend the forks will give you a different experience. I don't think the 'performance' can be calculated on paper or with with math. Two bikes with the same rake can and will act differently if the two bikes have different weight dispersion or rear suspension or many other things.
I had a bike with extreme rake and long tubes. As soon as you turned the handlebars it would flop......that was sitting still, start moving and it was the best handling trike I built, I never could figure out what the dynamics were that made that happen.
So the question is, "who is going to do this for you and what are they willing to promise as far as handling satisfaction for the money you're gonna shell out?"

A solution for you now is if you're going over the lines in twisties, SLOW DOWN....problem solved. Your bike is what it is. Just like a wing can't compare to a sport bike in the twisties.
"Fight until hell freezes over, then fight on the ice"

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Re: rake a trike

Postby sparrowhawwk » Wed Jun 12, 2013 10:57 pm

I have been building sidecar rigs and trikes for too many years to admit. LOL In 1990 I was co-founder of Champion Sidecars. Aside from the occasional home built rig the main way to reduce trail (yes trail, not rake) on a rig was with a custom built leading link front end. While very popular in Europe, links were not received well in North America because they were ugly. Here it is all about looks, not function.

Champion Sidecars were the first to start mass production of modified triple clamps for the GL1500 in 1990. It was the most popular new bike being used for sidecars at the time. We actually made a 6 degree change in the forks which of course caused the front end to drop slightly losing ground clearance. For a short time we tried making 1 1/4" longer fork tubes available to make the bikes level again but aftermarket tubes just weren't up to the quality of stock so at that time I came up with longer fork caps that allowed use of stock tubes and no more blown seals.

It wasn't too long before California Sidecars had a customer purchase a set that they put on a demo. The steering difference was so different that rather than use it for a while and get used to it they started making them with only a 3 degree change which I always thought of as half a solution after using ours for a while.

If you park the front wheel of a motorcycle in sand or gravel and turn the steering lock to lock you will notice a mark on the ground from the tire in the shape of a windshield wiper mark only upside down like a piece of pie. In doing this you will see the sweeping motion the tire goes through when you steer, trying to move sideways on the ground. This is what you are fighting with a sidecar or trike conversion. If you extend that pie shape into a complete circle you will see the center of the circle is ahead of where the tire is touching the ground (vertical line to the ground from the axle). The center of the circle is the point a line drawn through the center of the steering stem will touch. When you turn the bars that line is the pivot point everything turns around. The distance from the vertical line to the steering pivot line is the "trail". If you move the wheel forward closer to the center of the circle the "trail" is reduced and so is the effort required to steer.

I often see "rake, the angle of the steering stem, confused with trail reduction when modified triple clamps are used. Unless you are cutting the steering stem from the frame and welding it on at a different angle "rake" is not changed.

On my personal sidecar bikes I reduce "trail" down to 1 1/4 inches. That is a little extreme for most people, mostly because it takes some miles to get used to. Once you adjust to it however you don't even notice it except that your steering is pleasantly light and quick and in some cases even low speed steering wobble can be reduced although it is not usually the main cure.

There are a number of different ways to accomplish this depending on the motorcycle involved but I won't get into that here.

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