Z800 Cafe Fighter Chopper thing GEOMETRY SPECS

Cheers for that dude.

I figured I'd have to use an offset sprocket. Tyre will be a 150 or 160 tyre.

My question would then be by dishing the hub out to get my best chainline (and keeping the rim centred to the frame / front wheel) what about the rear disc? Shpould I space that out or fab the caliper mount to meet the disc?

And how much is too much dish-wise before the load from the engine and brake force tears the thing to shreds on what is essentially an unbalanced wheel?

Aside from 'dish' (which I don't know a whole lot about) another thing to consider is chain to frame clearance.

On my 650 I'm running a 14mm offset front sprocket with a washer behind it, which puts me at around 16-18mm offset at front.

This is about as wide as you can go without altering the frame, I have some 4-5 mm clearance between chain and frame and don't really want to go any closer.

royalratch wrote:

Cheers for that dude.

I figured I'd have to use an offset sprocket. Tyre will be a 150 or 160 tyre.

My question would then be by dishing the hub out to get my best chainline (and keeping the rim centred to the frame / front wheel) what about the rear disc? Shpould I space that out or fab the caliper mount to meet the disc?

And how much is too much dish-wise before the load from the engine and brake force tears the thing to shreds on what is essentially an unbalanced wheel?

I see three options for dealing with the caliper position.

1) Use the caliper and hanger intended for the swingarm, and have a disk made to align. Sounds pricey.

2) Use what ever combination of disk and caliper that you choose, and have a hanger machined. Probably a little cheaper than having the disk made. This would be my most likely choice.

3) Use the caliper and hanger intended for the swingarm, and have a spacer machined to align the disk. This assumes that the disk would need spacing out. Probably the cheapest option, but I don't like adding spacers between the disk and hub.

Now on the dish issue. Obviously you want the dish at a minimum, but not for the obvious reason. The key factor with a spoked wheel is the transmission of drive or breaking through the spokes. Now on a bicycle, the convention is to to offset to the drive side since the cassette is relatively wide. This also has a positive side effect. The shorter spokes are actually a little stronger. The off side spokes take less of the torque, and so their strength isn't as critical. Offset is better in this case. Now the motorcycle needs them more balanced since you have drive and breaking on opposite sides of the hub. The dish really doesn't have much effect on balance except that it puts more load on the bearings of one side of the hub. Most motorcycle hubs have a third bearing in the sprocket side of the cush drive which offsets this anyway.

With your 150 or 160 tire, hopefully you won't need too much counterahaft sprocket offset. I'm running a 180 and needed 1/2" offset on a KZ1000.

Stay tuned for pictures to demonstrate dish. Give me a second.

Ok let me try for a graphic demonstration of dish using my road race bicycle. First picture is the front wheel with no dish:

Don't forget to click the pictures to enlarge:



Notice the spokes are angled evenly on both sides of the wheel. Now lets look at the rear wheel:



Hopefully you can see that the spokes are angled off one side, but you cannot see the spokes on the drive side. This bike uses a relatively wide 10 speed Shimano cassette. This drivetrain requires a lot of dish to center the wheel in the frame. Basically the drive side spokes are nearly straight in line with the centerline of the rim. The off side spokes are significantly longer and at a much greater angle.

I need to add that I am really enjoying your thread. You are causing me to have to think a little. That's a good thing. Cheers!

is this rim from a stock KTM bike?
it would be beneficial to u , to get a hold of the intended KTM,rear brakes cal , hanger, and wheel spacers from Ebay before u get carried away?

Not really.

I'm using an 90's Kawasaki swingarm and KZ750 chainline with a 150/160 rear tyre.

The rear wheel is just a custom SuperMoto wheel that is close to KTM spec but not for a KTM specifically. Rim size/width is 17" / 4.25".

I'm going to get my chainline sorted then probably have the a mix of minimal spacer and custom caliper mount to get the brake side correct.

It's a custom - so customize I will!

ratch,
don't forget to take planty of pictures!:laugh:

i am really enjoying following along on this thread,
keep us posted,

leon

Rearsets arrived!

Prefer these to fancy intricate type as they're a bit chunkier and 'period-ish' looking. Need to be anodized Black tho which will destroy the PTFE coating in the joints.





Guys - which ends goes to the shifter rod - and does it look like it will work...?


Yum yum!

Ratch, I would connect the end with the balljoint to the rearset, and then sort out the other end when I figured out what sort of a linkage was being attached to the splined shift shaft. You might have an issue with that straight connecting rod conflicting with your sidestand. Just something to check out before you get to final assembly.

I like the look of those rear sets. Where did they come from? Same machine shop that did your triple trees?

No. This is a small race supplies firm that sells them to fit most sports bikes. They're not mass made and marketed - each set are machined in small batches and are not immaculately finished - kind of in fitting with the GP style.

I just found all the factory rear seats and hi-end versions too fancy and wanted something a bit more butch and period looking, rather than obviously 'stick on.'

That's about the same reason that I made my own.

this bike is absolutely amazing...the wheels...the ohlins...the brembo mc....dear god i think im in love

props on the great build and the awesome thorough thought process!

Bearshawk