Topic: New project- Wheelie machine

[JP]

So I'm starting to think that I may be a hobby-aholic.  The Street Tracker is finished, the 550SS is done and will sale this tax season, and I am chomping at the bit for my next project.

I already have a huge lead on MY 750SS, i.e.- it is already completely dissassembled, powder coated, tank work has started, and I have begun to tear into the engine.  However, this is not enough.

As I lay in bed unable to sleep the night before last, I had an epiphany.  You see, I aquired 3 cb350's mid last year and decided that it would not be profitable enough to turn them into cafe's.  So I gave one of them to a troup of boy scouts, and every other Wednesday they come over and work on restoring it and they will sale it to raise funds once they finish.  So, this leaves me with two more- of which I am certain that I could make one working bike- but I don't think it would bring me enough money for it to be worth my time.

Here comes the epiphany-  I will use the two 350's to make a completely wild wheelie machine.  So far, here's what I have in mind to make it stand up at will.

1.  Hard tail with the rear wheel pushed as far forward as possible.
2.  Stationary chain tensioner on top of chain at a radical angle to help frame lift as chain tightens.
3.  Dirtbike front wheel setup with no front brake and a little drag tire.
4.  Rider position directly over centerline of rear wheel.
5.  Handlebars will be a custom bend to allow the rider to sit comfortable all the way at the back.
6.  Axle pegs to stand on.
7.  Wheelie bar that will actually hold bike and rider in a wheelie so learning won't be so scary.
8.  Huge rear sprocket.
9.  16"x4" rear magnesium rim and friggin huge low press. rear tire.
10. It will be known to all as....'The Trixter'

JP

And yes, I am serious.

[Jinxracing]

Just a thought...if the frame is a hardtail how will chain tension/angle help with lift? Seems to me that chassis attitude and the weight transfer that causes it are a result of the swingarm compressing.

[JP]

I'm trying to sort everything out in my head, (it get's pretty clustered up there) but I'm pretty sure it will still work.  You see, the tensioner will be on the top of the chain and pressing down, making the chain into a slight 'V' shape.  As the chain tightens, it will naturally want to push the top out level, thus pushing hard against the tensioner.  If the tensioner is mounted in front of the rear wheel, it will provide lift to the frame and a downward force to the rear tire.

I once got to ride a Yamaha Banshee with a chain tensioner on it and it was wicked cool!  It didn't wheelie a lot because it had rear suspension that would extend out when throttled, but it would lift up about 2 inches in the back every time.  The whole idea of a tensioner is to apply downward force to the rear tires giving more traction for better starts.  My hopes with the tensioner/hardtail comb is that  the force will have no option but to go directly into chassis lift.

JP

[mlinder]

With a hardtail, I can't see anything adding 'downforce' to the rear wheel outside of the transition of weight from front to back by moving forward...... It's static in it's positional relationship to the frame...
Maybe I'm not understanding.

[JP]

I'm not 100% sure of it either.  It's in it's conceptual phase and I am trying to work it all out.  If anyone has suggestions on how to make it wheelie easy....I'm all ears.  I'm not doing this for anything other than fun fun fun, so it doesn't need to be cool or look good, just jump up and beg at the twist of the throttle and I'm not expecting to do that with sheer grunt power from the little 350   So, I'll need all of the engineering tips I can get to make it work.

JP

[mlinder]

I'm not 100% sure of it either.  It's in it's conceptual phase and I am trying to work it all out.  If anyone has suggestions on how to make it wheelie easy....I'm all ears.  I'm not doing this for anything other than fun fun fun, so it doesn't need to be cool or look good, just jump up and beg at the twist of the throttle and I'm not expecting to do that with sheer grunt power from the little 350   So, I'll need all of the engineering tips I can get to make it work.

JP

Well, neither a chain tensioner or anything else back there will help a rigid framed machine wheelie better.
Torque and a center of gravity that is closer to the rear will be what you are looking for.
A rigid frame is also going to take much more of a beating on landing your wheelies.

[JP]

mlinder,

Your comment about "static" coupled with my boss's ideas made it click for me.  You are correct.....I think.....about it not making a difference.  My boss and I came to the conclusion that as long as the chain is tight, with it being a hard tail the force will go directly into driving the bike upwards and forwards.

I think my only real engineering concepts will be to raise the engine so that it sits above the centerline of the rear wheel, keep the front end as light as possible, and rider positioning.

I am so stoked over this project.  I just hope it turns out the way it is in my head.  Back when I used to race atv's, my friends called me the wheelie king.  I could wheelie up hill, down hill, upshift AND down shift, and even get it on one wheel for a little bit.  I've just never really had the cahonies to do it on a bike.  Hopefully this will make it easy for me to learn how to wheelie a bike.

JP

[mlinder]

mlinder,

Your comment about "static" coupled with my boss's ideas made it click for me.  You are correct.....I think.....about it not making a difference.  My boss and I came to the conclusion that as long as the chain is tight, with it being a hard tail the force will go directly into driving the bike upwards and forwards.

I think my only real engineering concepts will be to raise the engine so that it sits above the centerline of the rear wheel, keep the front end as light as possible, and rider positioning.

I am so stoked over this project.  I just hope it turns out the way it is in my head.  Back when I used to race atv's, my friends called me the wheelie king.  I could wheelie up hill, down hill, upshift AND down shift, and even get it on one wheel for a little bit.  I've just never really had the cahonies to do it on a bike.  Hopefully this will make it easy for me to learn how to wheelie a bike.

JP

The chain will be tight by virtue of the the front gear pulling against the rear gear which has the friction of pavement against tire going for it.
A non-rigid frane construction will be a bit safer and easier, i think, for wheelies.

[Jinxracing]

A non-rigid frane construction will be a bit safer and easier, i think, for wheelies.

To expand on that a little...having a suspended rear end can be a big help for wheelies if you set it up right. A very low swingarm pivot relative to the heights of the two sprockets will compress the rear suspension under acceleration causing quick weight transfer to the rear and even quicker wheelies. 

Take a look at some WSB and GP bikes...many of them have adjustable rear swingarm pivots to help control weight transfer under acceleration. If you're going to go full-geek on the engineering, an adjustable swingarm pivot would be the hot ticket for a dedicated wheelie machine. Raising the engine won't do much for you in the weight distribution department, but it would raise the front sprocket relative to the swingarm pivot which would help, assuming you have a swingarm that is. 

[ieism]

I don't really see why you need to turn it into a hardtail. I'm not a wheelie-expert on motorcycles, but I know a bit about wheelies on a bicycle. On a hardtail it might be easier lift the wheel for a few meters, but a softtail is much more controlled when you're doing wheelies for long distances. I can imagine shifting gears while doing a wheelie would work better on a softtail too.

So what makes a bike easy to wheelie?
1. Torque, horsepower is not that important. Once you get the wheel up, it just takes balance and bit off speed to keep rolling. A 4 cylinder is not ideal, trail and motocross bikes are usally v-twins or thumpers, for good reason.
2. Low gearing. This is the easy part.
3. Low weight..... My mate has a 300cc trailsbike that I ride sometimes, it's only 150 pounds!!

[JP]

No doubt, the 350 is not the ideal candidate for this venture- but, it's what I have laying around.

I think the hard tail will make it easier to wheelie as long as I construct it properly.  I know that people have said that the shocks will compress and transfer the weight to the rear, and that is without doubt true.  But as those shocks are compressing, I think that they are absorbing much needed energy.  I think it will be a better setup to build the hard tail in an already squatting position, therefor your weight is already transferred to the rear and no energy is lost trying to compress the shocks.  It should be instantaneous.

JP

[ProTeal55]

You gonna paint a #3 on this one too, or is this gonna be #4 ?

[JP]

He he he

No numbers, but the bike in my head is a bright orange with green and gold trim. 

JP

[Flying J]

SO whats up with this one?

[kirkn]

A FIVE-YEAR old thread?  Hmmm.....  probably long gone. 

[LesterPiglet]

I should really look at the post dates in future. 

[Flying J]

LOL, sorry, i didnt even notice the date.