Rear Rim offset Grimeca Hub

Paul Marx said:
I'm off guitar hunting tomorrow ........ then a haircut!
Paul
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With a straight-edge across either the rim and measure to the hub or the hub to the rim if the hub is wider. Both sides. Often just tightening the spokes evenly from the outset has the offset pretty well spot on.
 
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Was told by an expert wheel rebuilder that if your hub flanges are parallel then there is no offset. Don’t know if it’s true but it does seem logical. I await with bated breath to be shot down.😂😂😂
Tom
 
I imagine the rear wheel sits centrally in the swingarm. If it does, put two marks centrally on the front of the swingarm which are the width of the rim. Then fit the hub to the swingarm and measure your offset readings.
 
martymoose said:
I have Brians 1968 GT downstairs, how do you measure it? I'll be mucking around with the bike tomorrow, so can take a measurement
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That would be very helpful, to measure accurately the wheel needs to be out. Put a straight edge across the hub and measure the distance from that to the widest part of the rim. 01 in the drawing below. If the tyre is on the straight edge needs to be long enough to sit on the hub and reach the rim but not so long it fouls the tyre. It needs to be done both sides please.618FF6C8-76E3-46E1-B9E4-9875666D4998.jpeg89B48999-5EDE-4EAD-9FCE-200CDEEF076A.jpegFA256725-D193-4875-83FF-870DACCAA9E3.jpeg
 
Normski said:
That would be very helpful, to measure accurately the wheel needs to be out. Put a straight edge across the hub and measure the distance from that to the widest part of the rim. 01 in the drawing below. If the tyre is on the straight edge needs to be long enough to sit on the hub and reach the rim but not so long it fouls the tyre. It needs to be done both sides please.View attachment 69559View attachment 69560View attachment 69561
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I have a wheel alone somewhere.
Will see if I can get a more accurate measure.
Paul
 
All this depends on the hub being central to the rim. Not sure if Laverdas have a dead central config but easy to test - ideally yes. It's essential to fit the axle and all the spacers/washers in their correct positions (everything that sits inside the swingarm dropouts), tighten to assure you have the fitted width Measure the total width - rim centre is half this figure. You then have a reference point to work from, using the rim width as your determining factor. Hope this makes sense.
 
piranha-bro2 said:
All this depends on the hub being central to the rim. Not sure if Laverdas have a dead central config but easy to test - ideally yes. It's essential to fit the axle and all the spacers/washers in their correct positions (everything that sits inside the swingarm dropouts), tighten to assure you have the fitted width Measure the total width - rim centre is half this figure. You then have a reference point to work from, using the rim width as your determining factor. Hope this makes sense.
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Not necessarily.
Wheel doesn't have to be central.

Paul
 
Paul Marx said:
Not necessarily.
Wheel doesn't have to be central.

Paul
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That's exactly my point, Paul. Doesn't matter what or any offset there is between the hub and rim. What matters is that the rim is central to the swingarm, and the primary and rear sprockets align - the wheel spacers play the part here.
 
Just after I got my 3c I found it weaved a lot. I built a complicated jig to measure wheel alignment and found the rear wheel out of aline with the front by 7mm, it was parallel but off-centred. But what centre was the question, so I went with a line centred in the middle of the front wheel and midway from the frame plates that hold the swingarm. I was thinking of offsetting half of that 7mm with spoke adjustment to centre this TILL I learned the bike should have 2 wheel spacers on the left side, the tube-like one and that approx 5mm thick washer one as well. The washer was on the outside of the swingarm instead of inside. That not surprisingly this made a huge difference, the bike steers straight and true since that fix. Anyway, this stuff isn't easy to measure or even decided what datum to measure from. I think some bikes have off-set wheels as standard, shaft drive BMWs maybe?
 
piranha-bro2 said:
That's exactly my point, Paul. Doesn't matter what or any offset there is between the hub and rim. What matters is that the rim is central to the swingarm, and the primary and rear sprockets align - the wheel spacers play the part here.
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I understand, but the question concerned a wheel builder wanting to know the offset of the hub in the rim which is necessary to building the wheel, not spacing it in the bike.

Paul
 
Put the hub into the swingarm with axle, spacers, washers and nuts. Then measure from the spoke holes to the side of the swingarm on each side. If the measurement is the same there is no offset dishing. If the measurements are different, that is your offset, and may require different length spokes.
 
I have to say that this is a classic example of what happens in exams that people fail :ROFLMAO:. A simple question gets the most amazingly complex answer full of heaps of supplementary information but not the answer.
Our teachers drummed into us RTQ/ATQ (read the question/answer the question).
But this is the forum and we can rave on about all the buts and ifs and maybes, all good fun.
As Paul points out, it was a very simple question, and there were even diagrams and photos showing how to measure it, but nobody has yet come with the figure.
If someone has a wheel to measure please also give the rim width, the pic Normski put up appears to be wider than a standard WM3.
 
Tippie said:
I have to say that this is a classic example of what happens in exams that people fail :ROFLMAO:. A simple question gets the most amazingly complex answer full of heaps of supplementary information but not the answer.
Our teachers drummed into us RTQ/ATQ (read the question/answer the question).
But this is the forum and we can rave on about all the buts and ifs and maybes, all good fun.
As Paul points out, it was a very simple question, and there were even diagrams and photos showing how to measure it, but nobody has yet come with the figure.
If someone has a wheel to measure please also give the rim width, the pic Normski put up appears to be wider than a standard WM3.
Click to expand...
As far as I know, all Laverdas twins and triples had the rims laced in the center of the hub.

Marnix
 
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