#21
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Spoking wheels
On 11/23/2017 6:33 PM, John B. wrote:
On Thu, 23 Nov 2017 10:36:06 -0500, Frank Krygowski wrote: On 11/23/2017 3:13 AM, John B. wrote: On Wed, 22 Nov 2017 09:44:38 -0000, "Graham" wrote: "John B." wrote in message ... I'm rebuilding a rear (derailier) wheel as, to be frank, I used spokes that were slightly smaller in diameter on the cassette side of the wheel then probably wise, and had occasional spoke breakage. I finally got some slightly larger diameter spokes and am lacing the cassette side of the wheel. Over probably a couple of years I had four spokes break, one at a time, all were what Sheldon referred to as trailing spokes, the ones that have the highest strain when pedaling, and all broke at the middle of the bend at the head end. While I was lacing the wheel with the new spokes I got to wondering whether the side of the hub flange that spoke heads were on might have had any effect on strength. I have always laced 36 hole wheels over three for rear wheels and over two for front wheels with the trailing spoke heads on the outside of the hub flange and the leading spokes with the heads on the inside of the flange, as I believe that Sheldon recommended. But I also remember someone here with a rant about rear wheel lacing who I think was recommending that on the cassette side that the heads should all be toward the outside of the flange. I assumes to prevent damaging spokes if the chain were to come off the largest cassette cog and jam between the spokes and the cassette. This is the only wheel I've had problems with and I deliberately bought the bits and pieces with the idea of long life in mind - cartridge wheel bearings and medium weight rim with eyelets, etc., and as this is the only wheel that I've had problems with I'm fairly sure that my wheel building technique is reasonably effective. Any thoughts on spoke head orientation and the effect on spoke strength. -- Cheers, John B. FWIW I have always used the method described in Gerd Schraner's book on wheel building and I have no problems with wheels going out of true or spokes breaking. Schraner discusses your point and concludes that in his opinion it does not much matter whether the spokes at the hub are laced in a symetric or mirror image pattern or whether the driving spokes are head out or in. From his long experience of wheel building he has concluded that there should be a very marginal gain to have the driven spokes heads in on the cassette side and that is what he recommends. His logic being that it very slightly increases the angle to the rim and thereby slightly reduced tension. However it is clear he would not get into a flame war over it. His main contention is that it is the quality of the components and the build that determine how a wheel performs. On spoke elbow breakages he stresses the need to bed the spoke heads into the hub and to correctly tension and stress relieve the wheel. Graham. I tend to agree with you as I've built wheels in all sorts of style and have seldom had any problems which was what was puzzling with this particular wheel. It was straight and would go for months and then pop, one spoke on the drive side would pop the head off and the wheel would wobble. I'd take the wheel apart and check everything change the spoke and re tension and it would go for months and then pop. The last time it popped two spokes about 180 degrees from each other and I decided to do something a bit more permanent and replaced all the drive side spokes with a thicker spokes. About thicker spokes: I do believe that butted spokes (thinner in the middle) make stronger wheels. When building new wheels before our biggest tour, IIRC I got butted spokes with extra thickness at the end with the head. Sorry I don't now remember the brand or gauge. It's been a long time. I could go measure measure, but I'm late heading for a big dinner. Theoretically you are probably correct but I wonder whether this is another of those Brandt situations where the difference is academic. The difference in weight of a wheel built with butted spokes and non butted spokes would be tiny and my guess that the difference in the strength of the wheel would be would be, essentially meaningless. A wheel that could support, oh say 1,000 lbs, and a stronger wheel that would be, maybe 20% stronger is probably not meaningful when it comes to bicycle wheels. -- Cheers, John B. It's not static load, which is already remarkable high for a bicycle wheel's weight, but rather impact resilience. Butted spokes, all else being equal, do last longer. -- Andrew Muzi www.yellowjersey.org/ Open every day since 1 April, 1971 |
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#22
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Spoking wheels
FWIW, a few years ago I was breaking rear spokes on the freewheel side, and the guys on here told me to check my spoke tension more carefully when I built the wheel (I had not been checking it properly). Although I was too cheap to buy a tensiometer, I found that by squeezing each pair of spokes together where they cross, any incorrectly-tensioned spokes become glaringly obvious. I've been doing that ever since, and haven't had any broken spokes for a long time.
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#23
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Spoking wheels
On Fri, 24 Nov 2017 09:29:40 -0600, AMuzi wrote:
On 11/23/2017 6:33 PM, John B. wrote: On Thu, 23 Nov 2017 10:36:06 -0500, Frank Krygowski wrote: On 11/23/2017 3:13 AM, John B. wrote: On Wed, 22 Nov 2017 09:44:38 -0000, "Graham" wrote: "John B." wrote in message ... I'm rebuilding a rear (derailier) wheel as, to be frank, I used spokes that were slightly smaller in diameter on the cassette side of the wheel then probably wise, and had occasional spoke breakage. I finally got some slightly larger diameter spokes and am lacing the cassette side of the wheel. Over probably a couple of years I had four spokes break, one at a time, all were what Sheldon referred to as trailing spokes, the ones that have the highest strain when pedaling, and all broke at the middle of the bend at the head end. While I was lacing the wheel with the new spokes I got to wondering whether the side of the hub flange that spoke heads were on might have had any effect on strength. I have always laced 36 hole wheels over three for rear wheels and over two for front wheels with the trailing spoke heads on the outside of the hub flange and the leading spokes with the heads on the inside of the flange, as I believe that Sheldon recommended. But I also remember someone here with a rant about rear wheel lacing who I think was recommending that on the cassette side that the heads should all be toward the outside of the flange. I assumes to prevent damaging spokes if the chain were to come off the largest cassette cog and jam between the spokes and the cassette. This is the only wheel I've had problems with and I deliberately bought the bits and pieces with the idea of long life in mind - cartridge wheel bearings and medium weight rim with eyelets, etc., and as this is the only wheel that I've had problems with I'm fairly sure that my wheel building technique is reasonably effective. Any thoughts on spoke head orientation and the effect on spoke strength. -- Cheers, John B. FWIW I have always used the method described in Gerd Schraner's book on wheel building and I have no problems with wheels going out of true or spokes breaking. Schraner discusses your point and concludes that in his opinion it does not much matter whether the spokes at the hub are laced in a symetric or mirror image pattern or whether the driving spokes are head out or in. From his long experience of wheel building he has concluded that there should be a very marginal gain to have the driven spokes heads in on the cassette side and that is what he recommends. His logic being that it very slightly increases the angle to the rim and thereby slightly reduced tension. However it is clear he would not get into a flame war over it. His main contention is that it is the quality of the components and the build that determine how a wheel performs. On spoke elbow breakages he stresses the need to bed the spoke heads into the hub and to correctly tension and stress relieve the wheel. Graham. I tend to agree with you as I've built wheels in all sorts of style and have seldom had any problems which was what was puzzling with this particular wheel. It was straight and would go for months and then pop, one spoke on the drive side would pop the head off and the wheel would wobble. I'd take the wheel apart and check everything change the spoke and re tension and it would go for months and then pop. The last time it popped two spokes about 180 degrees from each other and I decided to do something a bit more permanent and replaced all the drive side spokes with a thicker spokes. About thicker spokes: I do believe that butted spokes (thinner in the middle) make stronger wheels. When building new wheels before our biggest tour, IIRC I got butted spokes with extra thickness at the end with the head. Sorry I don't now remember the brand or gauge. It's been a long time. I could go measure measure, but I'm late heading for a big dinner. Theoretically you are probably correct but I wonder whether this is another of those Brandt situations where the difference is academic. The difference in weight of a wheel built with butted spokes and non butted spokes would be tiny and my guess that the difference in the strength of the wheel would be would be, essentially meaningless. A wheel that could support, oh say 1,000 lbs, and a stronger wheel that would be, maybe 20% stronger is probably not meaningful when it comes to bicycle wheels. -- Cheers, John B. It's not static load, which is already remarkable high for a bicycle wheel's weight, but rather impact resilience. Butted spokes, all else being equal, do last longer. Certainly true. But I was trying to simplify the equation and once you get into impact loading you then get into speed and the slow riders having to think up excuses for their wheels lasting so long :-) -- Cheers, John B. |
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