October 5, 201114 yr Hi all, I just wondered if any one knows how to work out the length of spokes needed for a wheel rebuild? I am trying to rebuild a wheel that had a 17`` rim on it. I am now going to try and put an 18`` rim on instead. As the hunt for 17`` trials tyres was proving to be impossible... Many thanks in advance.... Pete.
October 5, 201114 yr Hi all, I just wondered if any one knows how to work out the length of spokes needed for a wheel rebuild? I am trying to rebuild a wheel that had a 17`` rim on it. I am now going to try and put an 18`` rim on instead. As the hunt for 17`` trials tyres was proving to be impossible... Many thanks in advance.... Pete. that's a good one, if the hubs are the same maybe you can measure one from the 18" wheel, when in doubt get them a little longer you can always trim them off after installing, maybe you can just get a set for the 18" rim of around the same year model rather than having them custom made, I assume you are converting an early 123 to regular size wheels? probably been done a few times by some of the regulars here
October 5, 201114 yr found this http://spokeanwheel.110mb.com/ SL = Spoke Length RRSP = Rim Radius plus Spoke Penetration HSR = Hub Spoke Radius SAA = Spoke Anchor Angle HFO = Hub Flange Offset
October 5, 201114 yr If you have the original spokes from the 17'' wheel why not add half an inch onto the standard length, or just to be on the safe side three quarters of an inch and take off any excess.
October 5, 201114 yr Author that's a good one, if the hubs are the same maybe you can measure one from the 18" wheel, when in doubt get them a little longer you can always trim them off after installing, maybe you can just get a set for the 18" rim of around the same year model rather than having them custom made, I assume you are converting an early 123 to regular size wheels? probably been done a few times by some of the regulars here The donor hub is different. It had two different diameters for the spokes, I have now checked and the larger of the diameters is quite close to the size of the hub i want to use. And the spokes on that side are longer than the ones from the 17`` wheel!! So. With your advice i would think that they may be the size i want? I will try and lace up one side of the rim and see how it looks. Thanks for the reply Its not a 123 wheel, its a project build i am working on inspired by a bike a saw on this site. its a KL 250 engine in a Monty frame. The problem i had was i used the KL wheels. I only found out that 17`` tyres were not available once i had put a number of hours in to getting the wheel to line up.. Thanks again for the reply.
October 5, 201114 yr Author Thanks Motovintage I will print the formula and see if i can work it out with the parts in front of me, Its a bit too mind blowing for me to try and get my head round all in one go! But as i have said in my last post... I may have something to test it against now. With the longer spokes from the donor wheel. Thanks for the advise.
October 5, 201114 yr Author If you have the original spokes from the 17'' wheel why not add half an inch onto the standard length, or just to be on the safe side three quarters of an inch and take off any excess. And if all else fails... I will get some long spokes as suggested and either cut the excess off or maybe run a die down to increase the length? Not too sure this is the done thing... But i cant see why it wont work... Thanks for the info its all good for options... Day off tomorrow! So i will give it a go.
October 6, 201114 yr See if you can find where this came from http://ozvmx.com/community/index.php?topic=13130.msg208813#new
October 6, 201114 yr Author This may be of interest? Spoke Length Calculator GJ Thanks for the spoke calculators. I have looked at quite a few of these calculators and formulas, and if i am honest they all leave me scratching my head! They all use jargon i dont understand. I have fitted the spokes from the similar side of the donor wheel to one side of my old hub this morning. It looks like this could work out ok. But i am still not sure. I will now have to try and hunt down some more spokes of the same size. I am a bit surprised at the price of spokes! They are not really in the price range where you can take a chance and buy a bunch just to try them. I will see what i can turn up. Thanks again for the above info.
October 6, 201114 yr And if all else fails... I will get some long spokes as suggested and either cut the excess off or maybe run a die down to increase the length? Not too sure this is the done thing... But i cant see why it wont work... Thanks for the info its all good for options... Day off tomorrow! So i will give it a go. You could run a die down to help calculate the length, but not for the actual wheel build. Spoke threads are rolled, not cut.
October 6, 201114 yr Author You could run a die down to help calculate the length, but not for the actual wheel build. Spoke threads are rolled, not cut. I think i may have seen this said before, spoke threads are rolled? I dont really know what that is. Will this make it a non standard thread? If it is a standard thread rolled or not. Would you know why you could not add to its length with a die?
October 6, 201114 yr Author This is starting to get more confusing now. The donor wheel is looking like it has had a rebuild and that the spokes are not the right gauge. They are 3.1 mm and 180 mm long. The length may be ok but the diameter i am looking for is more like 3.6 mm. That is the diameter of the spokes from the 17`` wheel that are too short. So i am looking for a set of 36 spokes 180mm long and 3.6 mm diameter. Any ideas if these exist? And if they do. where i would get them at a reasonable price? I find it hard to look for spokes on ebay and the like,as the sellers dont normally give dimensions just the bike they fit. So i suppose the question is. What bike had spokes 180mm long and 3.6 mm diameter? I think this may be a long job!
October 6, 201114 yr I think i may have seen this said before, spoke threads are rolled? I dont really know what that is. Will this make it a non standard thread? If it is a standard thread rolled or not. Would you know why you could not add to its length with a die? I think the difference is a cut thread removes material, a rolled thread squeezes it to form the thread, ie no material lost. The nipples are obviously designed to accommodate. If you use a nipple on a cut thread there is little contact / strength.
October 6, 201114 yr I've seen (but never used) a wheel-building jig. It holds the rim and puts the hub in the center. I suppose if you could find or improvise something similar, you could just measure from hole-to-hole.
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