Front Drum Brake Hub offset

I thought i would be brave and try and build my own wheels, it's something I have always wanted to try. When I started I measured the hub to rim offset and cam up with 5/16 drum side and 7/8 hub side. I thought I read in Roy Bacon's book it should be centered?

Short answer, yes, rim centered in forks.
Long answer IMOH:
Ensure the wheel is true radially and more or less true axially
Torque the spokes to about 45-50 inch pounds as follows:
Tighten spokes 1/4 turn each until every spoke is sufficently tensioned (insufficient tension will result in broken or pulled through spokes as well as give funny handling)
Spoke tension is NOT absolute; your wheel should still be true radially but it will quite likely be wobbly axially.
Remove the axial error by adjusting tension as required.
I start, using the valve stem hole as a reference point, by adjusting each spoke in succession ONE QUARTER TURN at a time.
Adjust spokes in adjacent pairs - Tighten one and loosen the next or vice versa as needed, this helps keep radial alignment.
Keep at it until the wheel is true and each spoke has a nice satisfying " ping" when tapped.

To check the rear alignment, FENDER, Tank and SEAT OFF, simply run a string from the center of the top tripleclamp down the frame backbone and attach to the back of the frame.
Sight the string against the real wheel center line, any axial error will be obvious; I always try to finish wheels in the frame to ensure alignment.

To check rear alignment otherwise I stand the bike vertically without the center stand. Get an old 8 ft Flourescent tube for a nice lightweight straight edge and adjust as necessary.

Make sure you have no loose or insufficiently tightened spokes - They will break sometime you least need it.

Hope This Helps

I would doubt that a single sided TLS would be centered on the rim, you would normally need some offset to allow for the additional width of the brake plate. However, the rim should be centered in the forks.

Webby

Okay, I just gave it another go since I am home and bored(sick)
I loosened all of the spokes and got them all at the same starting point. I did the 6-12-3-9 o'clock positions first snugging them up. I then alternated with the rest of the sets of four. Now my offset is exactly what I measured when I dissassembled the wheel. Radial runout is around .040 if I am meauring right.

I started on the axial and now have it around .025-.035 runout....again, if I am measuring correctly. Is this close enough?

Seems to me when I did mine, the front rim was offset on the hub a slight amount. I set it up per original and then centered it between the forks. About 1/8 turn on each spoke, loosen on one side, tighten on other, will move it about 1mm as I remember. The rear needs to be pointing at the headstock, Jim's idea will work fine. I used a long aluminum rod and measured the distance to the headstock with the rod on the rims before I had the oil tank in. You can remove the shocks and rear fender and push the rear wheel up and get the same effect above the frame tube. I also set the rear wheel up per original and tuned it a bit to center it on the large tube. After I get it set up once I made a center mark on the web at the back of the main tube and use that to run a straight edge up from the rims or wheels to see that the offset is the same on each side so it's pointing straight. Only works if you know the wheel is centered on the main tube.

I rather enjoyed building my wheels. I did build one backwards first time, that is the spokes were going the wrong way, that was funny, but it went together just fine.

I think I got all my runouts within 1/2mm.

Dave
69S

I actually laced them three times :roll: I think I had them right the first time but didn't like the way the outer spokes had a slight bow so I took it all back apart and the laced it up wrong the next time. Took it all back apart again and laced it up correct.

I am glad I tried this, I always wanted to learn, even if it's the hard way!