Rear Wheel Offset?

This section is for all posts concerning frame design and construction.
User avatar
Nero
Tourist
Posts: 36
Joined: Wed Jan 18, 2012 1:51 pm
SELF INTRODUCTION: I'm an informatic engineer who just happened to leave his (relatively well paid) job to follow his passion and going to work at minimum wage as a CAD designer and a welder in a CNC laser cutting & general sheet metal fabrication shop.
In the meanwhile, I try to build a killer bike with whatever I have at hand...
Location: Siena, Italy
Contact:

Rear Wheel Offset?

Post by Nero »

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).
Situazione ruota post.JPG
Situazione ruota post.JPG (16.41 KiB) Viewed 6377 times
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... :roll:

So waddaya think? Is it an acceptable compromise?
What I'm currently working at (and some free Italian's lessons also :D ) : http://costafabbricustomchoppers.blogspot.com/
User avatar
gww25
Site Grandaddy
Posts: 219
Joined: Thu Nov 24, 2011 2:45 pm
SELF INTRODUCTION: I'm just an old chopper builders who still dabbles in the craft and I hope that I can contribute something to the discussions as time goes by. Most of you already know that I started the Chopper Builders Handbook site so you're probably already familiar with my philosophy on choppers and chopper work.
Location: Murphy, Texas
Contact:

Re: Rear Wheel Offset?

Post by gww25 »

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.
krymis
Conventioneer
Posts: 277
Joined: Sun Nov 06, 2011 12:46 pm
SELF INTRODUCTION: Hey dan it chris (krymis) from the CBH board. thanks for opening this back up. hope to have a project to show the build here. BLAH BLAH BLAH BLAH BLAH and so on and so forth. The book of revolations and worlds ends and shit like that.....

Re: Rear Wheel Offset?

Post by krymis »

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.
User avatar
Nero
Tourist
Posts: 36
Joined: Wed Jan 18, 2012 1:51 pm
SELF INTRODUCTION: I'm an informatic engineer who just happened to leave his (relatively well paid) job to follow his passion and going to work at minimum wage as a CAD designer and a welder in a CNC laser cutting & general sheet metal fabrication shop.
In the meanwhile, I try to build a killer bike with whatever I have at hand...
Location: Siena, Italy
Contact:

Re: Rear Wheel Offset?

Post by Nero »

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... :think:

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... :oops:
What I'm currently working at (and some free Italian's lessons also :D ) : http://costafabbricustomchoppers.blogspot.com/
User avatar
Nero
Tourist
Posts: 36
Joined: Wed Jan 18, 2012 1:51 pm
SELF INTRODUCTION: I'm an informatic engineer who just happened to leave his (relatively well paid) job to follow his passion and going to work at minimum wage as a CAD designer and a welder in a CNC laser cutting & general sheet metal fabrication shop.
In the meanwhile, I try to build a killer bike with whatever I have at hand...
Location: Siena, Italy
Contact:

Re: Rear Wheel Offset?

Post by Nero »

@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..
What I'm currently working at (and some free Italian's lessons also :D ) : http://costafabbricustomchoppers.blogspot.com/
krymis
Conventioneer
Posts: 277
Joined: Sun Nov 06, 2011 12:46 pm
SELF INTRODUCTION: Hey dan it chris (krymis) from the CBH board. thanks for opening this back up. hope to have a project to show the build here. BLAH BLAH BLAH BLAH BLAH and so on and so forth. The book of revolations and worlds ends and shit like that.....

Re: Rear Wheel Offset?

Post by krymis »

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.
Jeff L
Contributor
Posts: 687
Joined: Fri Oct 28, 2011 5:09 pm
SELF INTRODUCTION: Hey...I live in South Jersey (the Super Fund State) work as an Operating Engineer local825.Besides bikes I love to fish the surf.I have my current & seemingly endless project a BSA 750 Rocket3, a 72 Honda CB750,79 Kawasaki KZ1000, 48 Simplex, & a 62 Norton Atlas engine
Location: South Jersey

Re: Rear Wheel Offset?

Post by Jeff L »

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.
Changing the shape of the Earth...1 bucket at a time...IUOE local 825 top of the food chain
User avatar
railroad bob
Contributor
Posts: 939
Joined: Fri Nov 04, 2011 10:07 pm
SELF INTRODUCTION: Hi Dan, thanks for your time and energy spent on this new board. I hope you will give me a waiver on the email account, I have used gmail so long I don't have a clue what my service provider account is.
I just returned home from a 2 week trip in New Mexico, have a few good pix, can't wait to share my off-highway traveling. Got to put 1400 miles on the scoot.

Best, Bob Davidson
Location: Alaska

Re: Rear Wheel Offset?

Post by railroad bob »

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
Alaska - Land of the Individual and Other Endangered Species
An Armed Society is a Polite Society,...
Politicians Prefer Unarmed Peasants
TANSTAAFL
User avatar
Nero
Tourist
Posts: 36
Joined: Wed Jan 18, 2012 1:51 pm
SELF INTRODUCTION: I'm an informatic engineer who just happened to leave his (relatively well paid) job to follow his passion and going to work at minimum wage as a CAD designer and a welder in a CNC laser cutting & general sheet metal fabrication shop.
In the meanwhile, I try to build a killer bike with whatever I have at hand...
Location: Siena, Italy
Contact:

Re: Rear Wheel Offset?

Post by Nero »

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.. :roll:
What I'm currently working at (and some free Italian's lessons also :D ) : http://costafabbricustomchoppers.blogspot.com/
User avatar
jimmib
Lurker
Posts: 91
Joined: Tue Oct 25, 2011 1:35 pm
SELF INTRODUCTION: Hello everyone. first of all a big thanks to "Dan the Man". Some of you know me from the previous (2) boards and some don't, so here goes. I have been a fabricator/welder for over 40 years now. Damn that's a helluva long time to do anything! Anyways, I have built literaly 100's of street rods, pro streeters, racecars, bikes and trikes over the years. Never made the headlines and never will. I do what I do because it is the love of my life.
I enjoy reading the posts on the forum and try to contribute when I can. I am sure that this will be every bit as good as the CBH forum, as we will have most of the same folks. Good luck and post a lot of pics!! Jim
Location: Lowcountry USA

Re: Rear Wheel Offset?

Post by jimmib »

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
Whoa!...Musta stood up too fast...
Ever stop to think and forget to start again?
An optomist is no more than a pessimist with an idea.
Gun control is hitting what you are aiming at.....
User avatar
Maz
Biker Mistress
Posts: 714
Joined: Tue Oct 25, 2011 4:02 pm
SELF INTRODUCTION: The Biker Mistress, Blonde, blue eyes, English Lady bike builder and previously a member of the CBH. I run my own custom bike and chop shop (MazChopz) on the south west coast of England. I have been building custom bikes for over 35 years and have built some 130 bikes so far. I am happy to share my knowledge and "expertise" and also hope to learn from the other forum members. I look forward to meeting up with many of my friends from the CBH and especially to seeing how Dan got on with his Knuck.
Location: South West Coast of England
Contact:

Re: Rear Wheel Offset?

Post by Maz »

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 :doh:

Maz xx
Blonde, blue eyes, English Custom Bike builder and Biker Mistress!!!

Image
User avatar
Nero
Tourist
Posts: 36
Joined: Wed Jan 18, 2012 1:51 pm
SELF INTRODUCTION: I'm an informatic engineer who just happened to leave his (relatively well paid) job to follow his passion and going to work at minimum wage as a CAD designer and a welder in a CNC laser cutting & general sheet metal fabrication shop.
In the meanwhile, I try to build a killer bike with whatever I have at hand...
Location: Siena, Italy
Contact:

Re: Rear Wheel Offset?

Post by Nero »

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... :roll:
What I'm currently working at (and some free Italian's lessons also :D ) : http://costafabbricustomchoppers.blogspot.com/
User avatar
Maz
Biker Mistress
Posts: 714
Joined: Tue Oct 25, 2011 4:02 pm
SELF INTRODUCTION: The Biker Mistress, Blonde, blue eyes, English Lady bike builder and previously a member of the CBH. I run my own custom bike and chop shop (MazChopz) on the south west coast of England. I have been building custom bikes for over 35 years and have built some 130 bikes so far. I am happy to share my knowledge and "expertise" and also hope to learn from the other forum members. I look forward to meeting up with many of my friends from the CBH and especially to seeing how Dan got on with his Knuck.
Location: South West Coast of England
Contact:

Re: Rear Wheel Offset?

Post by Maz »

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... :roll:
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 :doh: :obscene-drinkingcheers:

Maz xx
Blonde, blue eyes, English Custom Bike builder and Biker Mistress!!!

Image
User avatar
Maxthegardener
Builder
Posts: 384
Joined: Tue Oct 25, 2011 11:28 am
SELF INTRODUCTION: Name is Max living in scotland ,and building my first bike, Which is derived from a buellM2 Cyclone..Started with an engine and a Drop seat frame wich was made to my spec by a more experienced builder. would like to learn more about the skills and techniques required to build a frame so I value being a member here...Cheers Max
Location: Angus, Scotland

Re: Rear Wheel Offset?

Post by Maxthegardener »

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.
Jeff L
Contributor
Posts: 687
Joined: Fri Oct 28, 2011 5:09 pm
SELF INTRODUCTION: Hey...I live in South Jersey (the Super Fund State) work as an Operating Engineer local825.Besides bikes I love to fish the surf.I have my current & seemingly endless project a BSA 750 Rocket3, a 72 Honda CB750,79 Kawasaki KZ1000, 48 Simplex, & a 62 Norton Atlas engine
Location: South Jersey

Re: Rear Wheel Offset?

Post by Jeff L »

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.
Changing the shape of the Earth...1 bucket at a time...IUOE local 825 top of the food chain
Post Reply

Return to “Frame Fabrication”