Correct spoke length ?

[Invicta]

I am having a nightmare trying to lace the rear wheel of a 1949 model 18. I have new rims and spokes from the Devon rim co. I have a cotton reel hub , (not the 4" one ) My parts book shows spokes as 8 3/16" long. Those that I was supplied with are 8 1/4" long. On first build the outer spokes fitted but the inners appeared far too long. The spokes that I took out of the wheel that had been rebuilt by the PO many years ago were 8" long. Devon rim co reduced the inner spokes to 8" and when the rim was re fitted , the outer spokes now appear to be 1/8" to 3/16" too long.. I laced the rim following to the letter the instructions that I found on wheel building on the forum with the first inner spoke going into the first upward looking hole to the right of the valve hole. I have a 1950 model 18 and the rear wheel on that as original, is laced with an outer spoke going into the first looking up hole to the right of the valve hole. I rebuilt the rim copying this pattern and the result is a confused mess with every other alternate pair of both inner and outer spokes being too long, (if this makes sense) the outer spokes appearing even much longer than they did before, and . The spoke pattern looks right with each outer spoke crossing over 3 others. Can anyone tell me what the correct spoke length should be. Measuring the spoke length from under the head, and should inners and outers be the same length.? I have made no attempt at truing the rim, just tightening the spokes that will tighten down , very lightly, the others bottom out on their threads.
Cheers
Dave

[Mick D]

Hi

If you now have a set of spokes of identical length to those you removed and are using the original hub there are only two potential variables left - the rim is different or you are lacing it in a differing pattern.

Compare the two rims for differing dimensions or piercing patterns, if there are none you must be lacing it differently - did you take any photos of the wheel before you dismantled it?

Regards Mick

[Invicta]

Hi Mick,
Yes I did take photographs of the wheel from both sides before I dismantled it. Looking at them, the spoke pattern is the same. The inner and outer spokes are now different lengths, outers 8 1/4" I had the inners reduced to 8" which is what the inners I took out were. Unfortunately I can't find the rest of the old spokes to check if they were the same length inners and outers. They should both be the same length, so I will get the outers reduced to 8" as well. It would be helpful to know how AMC measured their spokes ie overall length, or as the Devon Rim Co do from the inside of the bend. I don't want to end up with a wheel with spoke thread showing all the way round. I have checked the Devon rim carefully in comparison to the Dunlop rim, and the only difference is in the depth of the 'valley' from the top outer edge of the rim down to the spoke holes . The profile is not exactly the same being about 40 thou different 0.080 overall, but I don't think that will account for anything. The drilling and dimpling is exactly the same. What I can't get my head round is why if, I start lacing the rim with an outer spoke in the first looking up hole to the right of the valve hole and keeping the pattern the same, instead of starting with an inner spoke in that same hole, it makes such a huge difference, as to which spokes then appear to be too long or too short. The spokes are in groups of four and the outer spokes each cross over three inner spokes. The strange thing is that with the spokes still loose enough for the hub to move slightly from side to side. On one side of the wheel, the outer spokes seem too long and the inners correct, and on the opposite side the reverse, the outers being correct and the inners too short . That is how it is if I start off with an outer instead of an inner in that fist looking up hole to the right of the valve hole, which is the way my 1950 rear wheel is laced. If I start off with an inner spoke in that fist looking up hole to the right of the valve hole then all of the outer spokes appear to be too long. There is e geometrical reason for this , there must be, but I can't see what it is.
Cheers Dave .

[Invicta]

Hi Mick,
Yes I did take photographs of the wheel from both sides before I dismantled it. Looking at them, the spoke pattern is the same. The inner and outer spokes are now different lengths, outers 8 1/4" I had the inners reduced to 8" which is what the inners I took out were. Unfortunately I can't find the rest of the old spokes to check if they were the same length inners and outers. They should both be the same length, so I will get the outers reduced to 8" as well. It would be helpful to know how AMC measured their spokes ie overall length, or as the Devon Rim Co do from the inside of the bend. I don't want to end up with a wheel with spoke thread showing all the way round. I have checked the Devon rim carefully in comparison to the Dunlop rim, and the only difference is in the depth of the 'valley' from the top outer edge of the rim down to the spoke holes . The profile is not exactly the same being about 40 thou different 0.080 overall, but I don't think that will account for anything. The drilling and dimpling is exactly the same. What I can't get my head round is why if, I start lacing the rim with an outer spoke in the first looking up hole to the right of the valve hole and keeping the pattern the same, instead of starting with an inner spoke in that same hole, it makes such a huge difference, as to which spokes then appear to be too long or too short. The spokes are in groups of four and the outer spokes each cross over three inner spokes. The strange thing is that with the spokes still loose enough for the hub to move slightly from side to side. On one side of the wheel, the outer spokes seem too long and the inners correct, and on the opposite side the reverse, the outers being correct and the inners too short . That is how it is if I start off with an outer instead of an inner in that fist looking up hole to the right of the valve hole, which is the way my 1950 rear wheel is laced. If I start off with an inner spoke in that fist looking up hole to the right of the valve hole then all of the outer spokes appear to be too long. There is e geometrical reason for this , there must be, but I can't see what it is.
Cheers Dave .

[Mick D]

Hi Dave

These things can be perplexing, especially without the items in front of you. First thought, you have set the correct offset haven't you and it is set to the correct side isn't it?

If you can get the wheel laced, tensioned and trued without the spokes becoming thread bound it's pretty easy to nip the excess thread off with a pair of end cutters and then grind the remainder back flush with an angle grinder.

Regards Mick

[Invicta]

Hi Mick,
I found all of the spokes that I had taken out of the rear wheel tonight while looking for something else in the garage. Now I don't know who fitted the new,(now old Dunlop rim), but when I examined the spokes carefully they were all the same length 8", but they were all the same and all appeared to be inner spokes with a bend slightly greater than 90 degrees. I don't think that there is any offset as both sides measured the same before I dismantled the wheel. Where the spokes appear to be too long cutting off the excess spoke that protrudes through the nipple is not an option as the thread bottoms out on the spokes before the end comes through the nipple. I am going to get the outer spokes shortened by 1/16" down to 8 3/16" and order a new set of inner spokes made to the same length as the outers as per the dimensions in my parts book, and see how I get on with spokes of the correct length. Cheers
Dave

[clive]

Difficult to give you advice because I have only built full width wheels which have straight spokes. However I did notice in your description that "I have checked the Devon rim carefully in comparison to the Dunlop rim, and the only difference is in the depth of the 'valley' from the top outer edge of the rim down to the spoke holes." Now rightly or wrongly I would have thought if the valley is deeper the spokes would need to be shorter that the originals.