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28 hole rim / 36 hole hub stuff
There are some really deeply discounted, nice 28 hole rims around. I'd
like to use some to build up some cheap wheels, but of course there aren't many 28 hole hubs laying around at all. I read the "Perverse Wheelbuilding" article on Sheldon's site (http://www.sheldonbrown.com/mismatch/). My questions: 1. Has anyone built up any of these? Any insights that aren't mentioned in the article? 2. Anyone built up any as rears, or as disc wheels? Anything exciting happen if so? 3. Anyone have any insights about whether there would theoretically be any problems with torsional strength using this lacing pattern as a rear or disc wheel? My intuition is that I'm pretty sure it'd be fine for normal rears, since most of the spokes are tangent and have angles that (I think) are similar to a 3x or 2x rear wheel, but I'm not sure about as a disc wheel and wouldn't be too comfortable fudging it. And just a disclaimer - I'm as into cool conventional wheels as all but the grouchiest, and I know that 28 holes, unusual lacing patterns, and the like are usually more gimmick than benefit. I'm mostly interested in this because I keep seeing closeout 28 hole rims. I do think that in general, 28 is fine if it's built right. Most of these rims are 26" as well, which makes it less of an issue. |
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#2
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28 hole rim / 36 hole hub stuff
Nate Knutson wrote:
There are some really deeply discounted, nice 28 hole rims around. I'd like to use some to build up some cheap wheels, but of course there aren't many 28 hole hubs laying around at all. I read the "Perverse Wheelbuilding" article on Sheldon's site (http://www.sheldonbrown.com/mismatch/). My questions: 1. Has anyone built up any of these? Any insights that aren't mentioned in the article? 2. Anyone built up any as rears, or as disc wheels? Anything exciting happen if so? 3. Anyone have any insights about whether there would theoretically be any problems with torsional strength using this lacing pattern as a rear or disc wheel? My intuition is that I'm pretty sure it'd be fine for normal rears, since most of the spokes are tangent and have angles that (I think) are similar to a 3x or 2x rear wheel, but I'm not sure about as a disc wheel and wouldn't be too comfortable fudging it. And just a disclaimer - I'm as into cool conventional wheels as all but the grouchiest, and I know that 28 holes, unusual lacing patterns, and the like are usually more gimmick than benefit. I'm mostly interested in this because I keep seeing closeout 28 hole rims. I do think that in general, 28 is fine if it's built right. Most of these rims are 26" as well, which makes it less of an issue. I'd say go for it! I'd use such a wheel even as a disc brake wheel or a rear wheel. Using the formula in _Bicycles and Tricycles_ I calculated the change in tension for my 24 spoke disc brake tandem wheel. It's 25 pounds at 1g rate of decelleration, IIRC. I'm comfortable with that, since in theory no spoke should go slack (minimum spoke tension is about 220 pounds) and max braking is very infrequent. Pedaling loads should be less. We can stop a lot quicker than we can start. ;-) So far (about 500 miles) no problems at all. |
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28 hole rim / 36 hole hub stuff
Nate Knutson wrote: There are some really deeply discounted, nice 28 hole rims around. I'd like to use some to build up some cheap wheels, but of course there aren't many 28 hole hubs laying around at all. 28h hubs are not hard to find, niether are 36h(I know not your issue). I read the "Perverse Wheelbuilding" article on Sheldon's site (http://www.sheldonbrown.com/mismatch/). My questions: 1. Has anyone built up any of these? Any insights that aren't mentioned in the article? 2. Anyone built up any as rears, or as disc wheels? Anything exciting happen if so? 3. Anyone have any insights about whether there would theoretically be any problems with torsional strength using this lacing pattern as a rear or disc wheel? My intuition is that I'm pretty sure it'd be fine for normal rears, since most of the spokes are tangent and have angles that (I think) are similar to a 3x or 2x rear wheel, but I'm not sure about as a disc wheel and wouldn't be too comfortable fudging it. And just a disclaimer - I'm as into cool conventional wheels as all but the grouchiest, and I know that 28 holes, unusual lacing patterns, and the like are usually more gimmick than benefit. I'm mostly interested in this because I keep seeing closeout 28 hole rims. I do think that in general, 28 is fine if it's built right. Most of these rims are 26" as well, which makes it less of an issue. |
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28 hole rim / 36 hole hub stuff
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#5
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28 hole rim / 36 hole hub stuff
On 11 Jan 2006 03:06:55 -0800, "Nate Knutson"
wrote: There are some really deeply discounted, nice 28 hole rims around. I'd like to use some to build up some cheap wheels, but of course there aren't many 28 hole hubs laying around at all. Decent but inexpensive 28 hole hubs are not as common used as 32 or 36, it's true, since performance-oriented 28-spoke wheels over 20" have neither been common for as long nor as popular as the others. I note that someone on eBay is trying very hard to dump a pile of 28h coaster brake hubs. With a little perseverance, though, a pair of hubs could doubtless be had...but with a little shopping around, I suspect that you could come up with just as good of a deal on a 32h or 36h setup. I read the "Perverse Wheelbuilding" article on Sheldon's site (http://www.sheldonbrown.com/mismatch/). My questions: 1. Has anyone built up any of these? Any insights that aren't mentioned in the article? It's a bit of a pain in the neck to do because of the various lengths of spoke needed, and there is no way that you can do it with equal spoke tension. As a result, under load, the wheel is likely to experience cyclic lateral deflection in the area where the greatest spoke unloading occurs, which is in the area of road contact. Since this is not in a location where the deflection will cause any frame or brake rub, it could perhaps be ignored...but in my opinion, it should give you a clue about the likely long-term durability of the product. 2. Anyone built up any as rears, or as disc wheels? Anything exciting happen if so? Given the known need for unequal left/right tension, and the already noted uneven tension within a side in the wheel under discussion, I believe that this is a bad idea. It is likely that the wheel would be difficult to get true and properly dished with adequate spoke tension everywhere.. 3. Anyone have any insights about whether there would theoretically be any problems with torsional strength using this lacing pattern as a rear or disc wheel? My intuition is that I'm pretty sure it'd be fine for normal rears, since most of the spokes are tangent and have angles that (I think) are similar to a 3x or 2x rear wheel, but I'm not sure about as a disc wheel and wouldn't be too comfortable fudging it. Braking forces are seldom at the magnitude of forward accelerations in a low gear on a hill. If the wheel will function under acceleration, it will have no problem with braking. The use of disc brakes is, therefore, irrelevant except for the fact that the typical disc hub has less flange offset than a rim-brake hub. In theory, this might actually make the proposed rear wheel easier to attempt since the left/right spoke tension imbalance is reduced, but it still looks like a bad idea. And just a disclaimer - I'm as into cool conventional wheels as all but the grouchiest, and I know that 28 holes, unusual lacing patterns, and the like are usually more gimmick than benefit. I'm mostly interested in this because I keep seeing closeout 28 hole rims. I do think that in general, 28 is fine if it's built right. Most of these rims are 26" as well, which makes it less of an issue. It's not hard to find 28-hole hubs. If you want to build a bargain wheel that's worth riding, match the hub to the rim and build it conventionally. Making a mismatch can be an interesting exercise when you have scrap bits lying around and nothing better to do, but when the object is to build a finished product that you're going to ride, the better plan is to stick with what's designed to work properly. -- Typoes are a feature, not a bug. Some gardening required to reply via email. Words processed in a facility that contains nuts. |
#6
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28 hole rim / 36 hole hub stuff
The prices I'm talking about are in the $5-10US range for relatively
high end rims that originally were in the $45-60 range. Lots and lots of this is available, seemingly all the time. The same isn't really true for 28H hubs. |
#7
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28 hole rim / 36 hole hub stuff
On 11 Jan 2006 09:37:44 -0800, "Nate Knutson"
wrote: The prices I'm talking about are in the $5-10US range for relatively high end rims that originally were in the $45-60 range. Lots and lots of this is available, seemingly all the time. The same isn't really true for 28H hubs. Any time you see last season's Hot Thing getting dumped cheap, consider the concept that if it was really all that good of a product, there would have been adequate demand for it to keep that from taking place. -- Typoes are a feature, not a bug. Some gardening required to reply via email. Words processed in a facility that contains nuts. |
#8
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28 hole rim / 36 hole hub stuff
In article . com, Nate
Knutson wrote: There are some really deeply discounted, nice 28 hole rims around. I'd like to use some to build up some cheap wheels, but of course there aren't many 28 hole hubs laying around at all. I read the "Perverse Wheelbuilding" article on Sheldon's site (http://www.sheldonbrown.com/mismatch/). My questions: 1. Has anyone built up any of these? Any insights that aren't mentioned in the article? I haven't used the approach outlined in sheldonbrown.com/mismatch, but I've built up wheels with mismatched hubs and rims[1]. My advice: if the purpose is the project itself, go ahead; if it's to build a durable wheel, where possible, use components designed for each other. Luke 1. http://groups.google.ca/group/rec.bi.../thread/ced77b f71f69de4e/eca63d2eebf1b21b?q=mismatched+hub+rim+luke&rnum=1# eca63d2eebf 1b21b or http://tinyurl.com/c9q8s |
#9
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28 hole rim / 36 hole hub stuff
Werehatrack wrote:
On 11 Jan 2006 03:06:55 -0800, "Nate Knutson" wrote: There are some really deeply discounted, nice 28 hole rims around. I'd like to use some to build up some cheap wheels, but of course there aren't many 28 hole hubs laying around at all. [...] and there is no way that you can do it with equal spoke tension. As a result, under load, the wheel is likely to experience cyclic lateral deflection in the area where the greatest spoke unloading occurs, which is in the area of road contact. How can uneven spoke tension cause uneven rim deflection? If the spoke is tight enough not to reach zero, then why would the stiffness be any different to a wheel with evenly tensioned spokes? 2. Anyone built up any as rears, or as disc wheels? Anything exciting happen if so? Given the known need for unequal left/right tension, and the already noted uneven tension within a side in the wheel under discussion, I believe that this is a bad idea. It is likely that the wheel would be difficult to get true and properly dished with adequate spoke tension everywhere.. My experience with 24 spokes in a 36H hub was easy. Sure, there are uneven tensions, but I don't see an issue with that in practice. There's a range of tension in any tensioned spoked wheel. The loosest spoke only has to be tight enough, then the tightest spoke is what it is. The range in a strange wheel might be a bit larger, but other than theoretically shorter rim life (due to the higher tension in the tightest spoke) there's no functional down side I see. Am I missing something? 3. Anyone have any insights about whether there would theoretically be any problems with torsional strength using this lacing pattern as a rear or disc wheel? Braking forces are seldom at the magnitude of forward accelerations in a low gear on a hill. This is opposite my hunch, but I admit we might be coming at this from different assumptions. I've always observed quicker rates of deceleration than acceleration, but it's not been gauged. It's be nice to make some measurements of accelerations/decelerations to find out. For example, I can stop hard eough to raise the rear tire, but I can't pedal hard enough to raise the front tire (unless I also jerk on the bars). [...T]he typical disc hub has less flange offset than a rim-brake hub. In theory, this might actually make the proposed rear wheel easier to attempt since the left/right spoke tension imbalance is reduced, Right, this is important to consider on any front disc wheel: no doubt the front hub's disc-side flange is closer to center than a similar non-disc brake hub's. But the rear hub's disc-side flange (on hubs I've checked, anyway) has about the same offset as the non-disc version, so for me it wouldn't normally be a consideration for the rear wheel. |
#10
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28 hole rim / 36 hole hub stuff
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