Front Offset

OK, on this pic, where do I measure the offset? From everything I have read, it should be smack in the middle of the forks. What is the best place to measure this? The right side bolt is snugged a bit and the left side slider is just resting on the shaft at this point.



I will have the same question on the rear when I get it together.

Thanks,
Dave
69 S project
JD2020

It looks pretty well centered to me...

As long as you follow the manual for use of spacers and assembly you should be there. As long as all the spokes go the same distance into the nipples it should be bang on the way it was designed. If you are re-using old spokes it would be a good idea to accurately measure each one to be sure they haven't been ground down before and are various lengths. If they have been ground before at least you'll know they will be different distances from the end of the nipples when the wheel is trued.

I reckon I will assemble the whole front fork and measure like ludwig suggests. I'll have to check to see that I have all the spacers/washers installed correctly. I don't want to install the tyres on the rims and then have to take them apart if the rims are not centered later. On my project, the rim and spokes are new, everything else is original. Centered within 1mm sounds good to me.

Thanks,
Dave
69S

OK, I've got the front end assembled less the frame. In the pic, the distance at A is about 2mm larger than B. That means the rim needs to go to the right by 1mm on the hub. There is a space of about 3mm on the left side (the red line), but I guess that doesn't mean anything because the left slider clamps tight onto the shaft at that point? The large end of the shaft is tight against the dust seal and bearing at that point, the dust seal does not rotate with the hub, it is fixed with the shaft. I'm going to loosen the spokes and re-do the offset 1mm to the right and I should be pretty close. Too bad because I had the rim up and down and side to side less than 0.5mm. Easier now than later though. It should only take a few hours.

I didn't measure distance A or B before I took the bike apart, I just measured the offset from the hub on the original wheel and set up the new rim like before, and that may have been off.



Dave
69S

I went back and forth about 4 times loosening one side and tightening the other. Seems that about 1/4 turn tighter on one side and 1/4 looser on the other will move the rim about 1mm. I have it within about .05mm now, I think that is good.

Now on to the rear.

Dave
69S

Dave,

Provided your wheels are reasonably straight and true before you take them apart, I've had good luck laying a 4' level across the flat part of the hub and measuring from that to the rim in several places on both sides. If you are using new rims and they are a different width you'd have to compensate for half the difference in width on each side. The front should be centered between the fork legs so it's pretty easy to get right without good measurements, but the rear is a different matter.

Nelson,
Thanks, I got new WM3 rims which seem to be just like the origs. Got new SS spokes and everything seemed to go together just fine, front and rear. Got the front centered, but now I am going on to the rear and am trying to figure out where the rims need to be in relation to the swingarm. This may be another project, I notice the engine cradle iso mounting is longer on the left side than the right side by 0.255". I guess that takes care of all the other offsets?? I need to figure out where the rear rim needs to be in relation to the swingarm mounts with all the spacers assembled?? Any ideas? I'm just starting on the rear, so I haven't really studied it much.

Dave
69S

ludwig,

Trouble is, everything is apart, engine out, cradle out, nothing mounted on the frame. I may have to put some parts together temporarily.

Dave
69S

After thinking about the rear offset, I will have to wait until I have the motor, cradle and enough back on the bike so I can set up the rear rim with the frame as ludwig suggests. So no rear tyre mounting at this point.

dave