Threewheeler rake.

[oeduardo67]

Hey you guys, I was wondering how I could measure the rake on a threewheeler or dirt bike? I'm planning on building a custom trike from a dirt bike. I know that many members have not recommended doing the conversion for aesthetic problems but I have nothing to lose. I know that first you have to have your rear end set at the preferred height angle but what is the best rake for an atc if you are running a leading axle? If running a trailing axle?

[JasonB]

Good questions, there was a couple links I found posted on here or .org for people adjusting rake on missle type bikes or dirt bike conversions. From what I u derstand the front needs to come down a little and the triple trees adjusted for proper amuont of rake, and the rear suspension adjusted as well. There have been a bunch of people in here and .org that have done it and very few successfully. It's a lot of work and the only person off the top of my head who has done it proper was Louis the mod in here. Search his cr500 atc500r conversion for more info on some tips for your conversion, he has like three threads on his on here

What bike are you using?

[oldskool83]

I think you can measure center line of steering stem against center line of forks. but if you jake up or lower you rear end takes thrown off.

[oeduardo67]

Thank you. I'll search him up.

I was thinking of building a trike for my little brother. Maybe a 125 2 stroke dirtbike. I also have the triple trees of a 200x and I was reading that it a complete bolt on to the small cr dirtbikes. have a rear end off of what seems to he a 200x. Complete with swingarm axle and brake parts. I think it would be more difficult to adjust the rear end with the rake of the linkages and spring. The rake I think I grind the factory welds until keep the single portion where the triple trees go mounted and weld it back on with proper gusseting and angle.

Do you think if I copy the 200x or 250r angle of rake I could make it function? I want the height in the rear to be a bit higher than an 83 200x but less than a 3rd gen 250r

[oldskool83]

somone used a 96+ cr80 already thru on the 200x tripples and forks and 200x rear end. It was for his kid thats all i remeber.

dirtbikes dont make great trikes, you'd be better off putting the CR80 motor in a 200x i think. either way its a hodge podge of stuff.

[oeduardo67]

Well I just wanted to do it for fun. I have all the parts so why not. I've never modified the rake and suspension setting on a dirtbike or atc so I wanted to see how it would come out to. Maybe I could try and integrate rake into the triple trees or flip the axle depending on what stance it has once the rear end is finished.

[El Camexican]

I've never done a trike, but I have raked a dozen bikes. Some with jigs and some without. It is not easy, simple, or all that much fun (at least not the cutting part), but if you have spare time, patience and are confident in your welding skills then have at it.

I’m not saying this is how you or anyone else should do it, but if I ever got so ambitious as to make a trike out of a bike I would model my frame off of a 250R as they seem to be the standard for handling and the design wasn’t restricted by patents as I’m lead to believe others were. You can determine your rake with a cheap inclinometer, but coming up with the right rake for your project is not as simple as that. You also need to figure out the trail and that requires taking a bunch of other measurements including, but not limited to steering head off-set, fork length, front tire diameter, trail and a couple other things I’m sure I’ve forgotten. There are sites on the Internet that can help you with the calculations, but unless you are some sort of master engineer you will want to model your project around something that has been proven to work and not try to reinvent the wheel.

I’d also try and mimic the 250Rin terms of the weight on the front wheel. Using three bathroom scales I’d raise the trike onto them and figure out what % of the overall weight is sitting on the front wheel and if possible try to get close to that % on your project. Moving the engine around is the most effective way, but if that’s not possible you could add ballast, or extend the swing-arm to make minor changes. Too much weight on the front and it will try to tip over and not enough and you will have a wheelie machine that doesn’t respond to turning the bars.

And finally, keep in mind that no matter the application weight is always best kept low, so if you find that your project is ending up with the engine two feet off the ground you may not want to proceed as it would be very unstable at speed. Give it only as much ground clearance as is needed and no more.

If you end up doing this please post it in real time.

[oeduardo67]

Thank you very much. I will certainly post any progress. Yes ima try and keep it "simple" by copying the design of the 250r. I am.going to use 200x forks but will also maybe make my own triples and mount inverts. More than likely just keep the 200x forks. I want to go with a custom billet hub that can accept 10 inch rims. Anyone have an idea how much that would cost? I'm not sure if I should simply just keep it a no link rear suspension like the x has or should I try to implement them. There's a lot to do but these are just some rough ideas.
what do you guys think?

[oeduardo67]

I've never done a trike, but I have raked a dozen bikes. Some with jigs and some without. It is not easy, simple, or all that much fun (at least not the cutting part), but if you have spare time, patience and are confident in your welding skills then have at it.

I dont know much about jigs. Ive heard about them when dealing with custom frames. What exactly is it and what is the function?
Thank you

[El Camexican]

Uff. Well as simply as I can put it a jig is a fixture that holds the frame in place and allows you to make adjustments and measurements. The attached photos are of my old Pro Mod turned Bracket Bike being transformed into a big wheel chassis. I had a 38 degree rake on it while running the 18 X 6 rim, but the new owner wanted to run a 15 X 10 rim and that meant changing everything but the cradle.

They are using a un-machined metal table with a steel block to locate the front axle and then just raising and lowering the frame in relation to that point as desired. It is NOT a professional jig, but it does the job. Now if money is no object you can get a 1” slab of steel stress relived, machined and fill it with tool steel bushing lined locating holes and make a zillion cool blocks, rails and clamps, but that would be the kind of thing you would see only in Sandy Kosman’s shop (Google him). In your case you want the trike frame to be on a relatively flat steel surface. This is very important when measuring things. If you can get something that is flat to say 1/16” overall then at least get some cold rolled steel square bars (at least 1”sq) and place them over the base plate to create a surface you can reference from. If its not perfect at least know where the imperfections are so you can compensate for them when you are measuring things.

You want to be able to ensure that A) your front axle is parallel to the swing-arm bolt. B) that both the axel and swing-arm bolt are level to each other and C) that the distance from the front axle to the rear axle is identical on both sides (left and right). I would do this by making a 3 foot shaft that fits the swing-arm pivot and a 3 foot axle for the front. This super exaggerated method will make it easy to check dimensions. On a bike a couple thousandths of an inch off on these measurements is nothing, but .05” over a 8” distance becomes huge when you put a 36” axle on the back. I hope I’m making sense here (not sure I ever remember your question) but I have to run. Basically I would pin the swing-arm pivot solid on the jig at the height you want it to be when you are riding and then manipulate the front axle to suit the rest of your needs. Just make sure you can hold it solid when welding.

Nuts! The photos are too big. PM me an email and I'll forward them.

[oeduardo67]

Pm sent. Thank you.

Does anyone know a rough estimate on what a custom billet hub would cost? Also anyone have or done anything with the no link swingarm in comparison with the links used. The 200x doesn't have shock links but most 125 dirtbikes do. Any suggestions or advice?

[El Camexican]

B) that both the axel and swing-arm bolt are level to each other To clarifly, they don't have to be the same level or height as each other, just the same level end to end with each other. Does that make sense?

[oeduardo67]

Okay one more question. In order to ensure a proper measurement with the rake would you tie the front steering down?

[barnett468]

Hey you guys, I was wondering how I could measure the rake on a threewheeler or dirt bike? I'm planning on building a custom trike from a dirt bike. I know that many members have not recommended doing the conversion for aesthetic problems but I have nothing to lose. I know that first you have to have your rear end set at the preferred height angle but what is the best rake for an atc if you are running a leading axle? If running a trailing axle?

Hello



“I was wondering how I could measure the rake on a threewheeler or dirt bike?”


I did this many times at Kawi and over the years. Kawi had a special “level” table just for this purpose. The industry standard for measuring steering head angle is the following.

1. Put bike on perfectly level surface, use level to check floor.

2. Air tires to proper pressure.

3. Lift frame until tires barely touch ground.

4. Center [straighten] front tire, bars etc.

5. Stick magnetic “angleometer” on steering head and forks at steering head. The steering head is the actual steering head angle. The forks are occasionally but rarely a different angle from the steering head ie different offset between upper and lower triple clamps.

6. That’s it.

Xxxxx

“what is the best rake for an atc if you are running a leading axle? If running a trailing axle?”


It depends upon what your riding type will be ie high speed or lower speed maneuverability required.

The best steering head angle for the use each particular bike is originally designed for is the one it came with. This is based on STOCK diameter tires.

If you decrease the steering head angle ie changing from 30 deg to 34 etc it decreases maneuverability [wider turning radius]and makes steering slower [less responsive] but increases high speed stability [picture dean sundall desert racing at 100 mph].

If you increase the steering head angle ie changing it from 30 deg to 26 deg etc, it increases maneuverability [smaller turning radius] and makes steering quicker [more responsive]etc [picture Jimmy White cutting inside the Hondas on his way to another Kawasiki powered Championship, Uh Oh I’m in trouble now, lol.], but it decreases high stability.


Hope this info helps.

[oeduardo67]

Thank you very helpful. I totally understand the difference between degrees when in relation to the bikes rake. A smaller sharper angle= better low speed riding and maneuverability while larger more extended rake= more stability.

Is 30 degrees a medium or average measure between aggressive mx style riding vs long distance desert riding or is it just an example?
thank you once again