Tech Tech Tech, or...So you want to build a trike?

[DeathBySnuSnu]

So did everyone read the tech links?
Does the basics of trail need more examples/explanations?

I could cad some examples.

 

[DeathBySnuSnu]

Another tech link to much of the same info.

http://www.motorcycle-superstore.com/4125/mngr/rake-and-trail-explained.aspx

 

[Gorilla]

Great job guys

 

[DeathBySnuSnu]

Here we go.

In an attempt to simplify in pictures.

This will be an example only, based off of some typical numbers

Here we have a donor bike.



Note the names of the geometery elements.

Also note that in stock motorcycle form it already has more trail than what you want for a trike.

 

[DeathBySnuSnu]

Now we want to cut this off the bike and weld it into the trike frame we are building.

Of course "raked out" is the cool thing to do. So naturally we want to increase its angle.

Guess what happens then.



No part of the bike front end has changed.

Only the angle it is attached.

Note the height will be lower.

And look at that trail.

 

[DeathBySnuSnu]

So now the head was too low to fit in the frame so now lets put 10 inch over fork legs in.



Got the neck up but did nothing to improve the trail. Actually because we most likely did not raise the back the same amout we rotated on the rear and gave it slightly more trail.

 

[DeathBySnuSnu]

So to make the stock hydraulic forks work we have to change the trees/yokes.

Increase the offset.



Or raked trees, yokes.

 

[DeathBySnuSnu]

The same geometry hold true with whatver neck height you want.

Way up 30 over, still the same rules.

 

[DeathBySnuSnu]

So now we have the aftermarket front ends.

The descriptions and dimensions are confusing as all get out. Seems to be no standard to anything. You must do the math and know exactly what you need to be able to find one with the right numbers to fit. Very very few places to buy a custom fit front end.

Same geometery with different forks.

Springer.



Drop pivot springer.



Leading link.



Different styles of front ends is not what fixes the trail.

It is the dimensions/numbers that make it right.

Any style of front end can be made correct.

Springer

Leading link

Hossack

Spirder

Telescopic

Girder

Shocker

 

[DeathBySnuSnu]

Now as we typically are building our own frames to no standard production dimensions the front end will have to be custom to it to be totally correct. Even though it may be possible to get there with carefully researched and fitted bought parts. Especially if you use all aftermarked harley parts as there is a large aftermarket for them.

By a large amount the most common front suspension for a hand built trike is a hand built leading link. It also is one of the easiest to build in a hobby shop in the garage.

 

[DeathBySnuSnu]

Tech link

http://trikerdon.50megs.com/leading_%20link%20_info.htm

 

[DeathBySnuSnu]

And another.

http://bettertrikes.yolasite.com/monster-leading-link.php

 

[DeathBySnuSnu]

You could even take that back half of the 2 wheeler you cut up and graft it into the front legs.

As long as the axle is in the right place it wont know that that is a rear swing arm and shock that used to be the rear end of a bike.

 

[DeathBySnuSnu]

As it is storming badly here I have not left the house this holiday. Would like to work on my trike build but just not going out in it.

So now you know... if you are going to build a trike you WILL have to work out the front end geometry.

Now for the "trike" part.

Rear ends.

Converting a bike is a good way to go. I like motorcycle based trikes.

Most start with a shaft drive and put a straight axle from a small car with a hand made mounting swing arm.

Chains and belts are a bit more difficult primarily because it requires more custom parts instead of junk yard salvage.

 

[DeathBySnuSnu]

Tech link.

http://www.thechopperunderground.com/forum/index.php?/topic/37455-building-a-bike-based-trike/

This link is dead.

The Chopper Underground is gone. It may be rebuilt and up in another form one day

 

[DeathBySnuSnu]

Keep it light and simple.

The motorcycle clutch wont take a huge load.

 

[DeathBySnuSnu]

When it cames to belts and chains I have seen some odd stuff but by far the most viable option is the bought diff units.

 

[DeathBySnuSnu]

Here is an interesting link.
But would take more than a hobby shop garage to build.

http://choppercompendium.com/ccforum/viewtopic.php?f=51&t=166&sid=09b3a210e6bb06cf198ae65fc17f3019

 

[DeathBySnuSnu]

Personally I would not do a hard tail.

Unless.....
It is only a sport about toy and the seating positions are well forward of the axle and the seats on springs.

 

[DeathBySnuSnu]

Big V-8 and other automobile engine trikes are still all the same geometry, just weight and spring rate differences.

Lots of good stuff at the junk yard for a big trike.

Ford in particular has a lot of independent rear suspension units in a bolt on package. Then there are misc others that could be used.