The Chopper Compendium

I was taking some measurments from a rear 6" channel rim taken from a Kawasaki ZX-12R complete with the axle and all the spacers and collars (it comes with a 200/50 tyre by factory) and it seems that the wheel is off-center by about 10mm-15mm (0.5"-0.59") to the right hand side (drive side is wider than brake side).
Considering that I will build the frame from scratch, I suppose that I'm faced with 3 choices:

1) build an asymmetric frame;
2) widen the space between the axle plates, and machine suitable spacers to make the tyre centerline coincident with the frame centerline;
3) use all the factory pieces the rim came with, and keep the wheel offsetted to the right.

I excluded option 1) almost immediately, I was evaluating option 2) but, considering the fact that I will be use a unit engine taken from a Yamaha Diversion 600, which used a 130 tyre, centering the wheel in the frame will shift the rear sprocket more towards the outside in respect fo the front sprocket, with more space to gain back to allign them from offsetting the engine/front sprocket, so maybe option no. 3) would be the best solution... the easiest for sure...

So waddaya think? Is it an acceptable compromise?

I'm not sure of what you're saying. Are you going to scrap the 200 tire and try to build with a 130? and keep the same driveline? At first glance this seems irrational if that's what you're trying to do so maybe I'm not getting what it is that you're doing.

you can take the trans sprocket off cut the center out to retain the trans spline pattern. Then lathe a pc of tubing to have the trans spline part fit the ID and the outer sprocket to fit the tubing OD. Then weld and true. The tubing will allow you to get in and tighten the sprocket to the trans.

No, I have a bike which has a 130 tyre (from which I'm taking the engine, the eletric stuff and not much more), and I'm trying to build a chassis that will accomodate this engine and a 200 rear tyre, which I stole from a Kawasaki, complete with its axle and spacers.

The problem is that this wheel seems not centered with the hub (I've just discovered that this is quite usual...), drive side is larger than brake side, so if I put it "as it is" inside a simmetrical frame with its axle & spacers, I will end up having a wheel not centered with the chassis midline, BUT maybe this condition will make it easyer to allign the sprockets... (the rear one will be more towards the midline)

On the countrary, if a build a slightly larger chassis and machine some appropriate spacers to center the wheel against the frame midline, the end result will be that the rear sprocket goes more towards the outside of the frame, and this will mean that I will have to offset more the engine (which was built for the 130 tyre) to align the front and the rear sprocket (or I will have to build an offset sprocket); I have to find this 35mm somewhere...

So I guess my question is if it is acceptable to have the rear tyre offsetted of about 0.5"-0.6" in respect of the frame midline (which I think would be), or if maybe it's better to place it straight in the midline of the frame, and build all the rest around it consequently...

Don't know if I was able to explain it in an understandable way...

@krymis:

yes, to offset the front sprocket, I will do something like that, but what about the rear wheel? Do you think that I should put it in the frame as it is, with all the orginal Kawa stuff (having it runnig offsetted to the right) or find a way to center it, and then make fit all the rest?

many thanks..

when i do them and have all the oem stuff i use it. make an asymmetric frame and call it good. if not wanting to do that...center the tire not the hubs but the tire and make proper spacers to accommodate the new wider space. you are making something that is very wide for no reason. Just use the kickout type rail and make it match up.

It pretty common when running a 130/16 on triumphs to offset the hub by 1/2" or so to clear the chain.Personally I think you should run a tire that will sit centered in the frame.

I think if you research it, you'll find that it is common for the rear wheel to have a slight offset to help with driveline alignment.
I believe I've seen that in several articles about different bikes, factory and custom.
When I first heard of it, I thought it might be an issue with handling, but the offset is so slight that it doesn't seem to make any appreciable difference.
If the hub and wheel are centered in the frame, the driveline extends to the side more than a bike using offset, which means more weight on that side also, and also affects the lean angle.

FWIW

That's exactly what I was thinking bob... my reasoning was that if the wheel is not centered on the hub by factory standard, maybe I could just take the whole wheel and use it the same way they do..
But then insecurity settled in, and I started wondering that maybe the orginal swing arm was somehow skewed to center the wheel..

i understand your question about the wheel offset, but if you are going from a 130 to a 200 tire, then you are going to have to offset something, ie, trans sprocket, trans and motor or wheel and tire. Or incorporate a jackshaft in your frame build.
Jim

Sorry guys I've been busy and missed this discussion - all larger metrics have offset drives and if you look at stock metric swingarms you can see this quite clearly. Whenever I've built British chops in the past and used a fat rear tyre I've had to re-spoke therear wheel with increased offset and then space out the drive or slightly offset the motor.....

But remember when designing your assymetrical frame to ensure both front and rear wheels track in line otherwise you will have an evil handling ride and one which won't pass safety inspections in most countries

Maz xx

So Maz you suggest to build an asymmetrical frame? What about building the frame slightly larger so as to aoccomodate some appropriate spacer to center the wheel instead?
Are there any cons? Because I think that it would look better than an asymmetric frame...

Nero wrote:So Maz you suggest to build an asymmetrical frame? What about building the frame slightly larger so as to aoccomodate some appropriate spacer to center the wheel instead?
Are there any cons? Because I think that it would look better than an asymmetric frame...

Personally I would go for a slightly wider frame and use axle spacers - that way you get a much better look.....the choice is yours, just make sure you get it straight

Maz xx

My heritage wheel was the same, and its running back to front, symetrical frame ,,spacers...centred the wheel measering off the rim to the frame....mine used a 10mm sprocket spacer front and rear

If when using your new wheel with a 200 Tyre makes the sprocket protrude more than the front then you'll have to space out the front sprocket, cant remember seeing a thread here but this guy has somewhere on his site
http://twizzlecustoms.co.uk/index1.html he made a custom front offset sprocket, with a bearing to take the extra strain you'll put on the tramsmission.

Is there room inside a Jap unit to space the front sprocket?I know there is no room on a Brit unit to do that.