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#21
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Mid & rear engine placement safety implications
On Wednesday, September 4, 2013 7:13:40 AM UTC+3, jim beam wrote:
> On 09/03/2013 08:48 PM, T0m $herman wrote: > > > On 9/3/2013 10:20 PM, jim beam wrote: > > >> On 09/03/2013 08:10 PM, T0m $herman wrote: > > >>> On 9/3/2013 8:23 PM, jim beam wrote: > > >>> > > >>>> see above retard. now, stop avoiding the question - go find a single > > >>>> rear engine car with less than 16" of crush space out front. > > >>>> > > >>>> > > >>> VW Type II? > > >>> > > >>> <http://silodrome.com/wp-content/uploads/2012/02/Volkswagen-Type-2-Kombi-Van.jpg> > > >>> > > >>> > > >>> > > >>> > > >> > > >> yeah, not the best. #12 in that diagram is a freakin' unfunny JOKE. > > >> > > >> > > > As a child in Quebec City, I spent time in the back of a VW Type IV - > > > snowmobile suit, mittens and boots were mandatory for any trip over 15 > > > minutes long, even with the optional auxiliary heater. > > > > > > > can't imagine. i had to wear every single piece of clothing i owned, > > including socks over my shoes, and that was just in oregon/seattle. > beats me how you survive in the giant air conditioner by the bay so you were implying never buy /read jobst book or that was not was you implying? I have other people do the wheel assembly and tensioning for me so I wonder about the need vs want vs just for laughs besides, I think I'll go mtb where wheel quality is of lesser importance than on a road bike |
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#22
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Mid & rear engine placement safety implications
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#23
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Mid & rear engine placement safety implications
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#25
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engine onnatop placement implications
>>>
>>> unfortunately, i don't think there's any one magic bullet on >>> wheel building books. jobst's book will allow you to >>> calculate spoke length from first principles [although, not >>> allow for the elongation that happens as they tension], >>> lace, true and tension, but it'll also have you >>> over-tension, bend spokes unnecessarily, and he gives you a >>> very iffy "stress relief" method. you'll also have no >>> initial clue on how to position a hub so the label aligns >>> with the valve hole, as per conventional practice. >>> >>> gerdt schraner's book will solve the hub label position >>> problem, and have you stress relieve better, but you'll be >>> reliant on others for spoke length. his lacing method is >>> also unnecessarily complicated. >>> >>> sheldon brown's online guide is very good on lacing, hub >>> positioning, but repeats a lot of the garbage that jobst >>> bullied into him. and his stress relief method blows chunks. >>> >>> if you can find it online, the mavic wheelbuilding guide is >>> pretty good. absolutely the best stress relief method. but >>> it tells you nothing about spoke length calculation, >>> presumably because if you're rebuilding a mavic wheel, >>> you're already using spokes of predetermined length. >>> >>> so, "don't read that book in isolation" is my advice. and >>> if you're thinking you want to understand wheel mechanics >>> and don't already have a strong understanding of mechanical >>> principles and materials, it'll badly **** you up because a >>> lot of what he says is just plain wrong. >>> >>> as to building wheels for yourself, we've discussed this >>> before. there are definitely benefits to learning in that >>> most people don't have access to a good builder. >>> statistically, that includes you. once you can build >>> yourself, and you take the time to do it right, which most >>> shops seldom invest, you can have a wheel that remains true >>> and stable almost indefinitely. that's a rare beastie in >>> "other people built" wheels. my mtb wheels, complete with >>> unconventional rear spoking pattern*, have remained >>> completely true despite some fearful abuse. same for my >>> townie fixie on san fran's pot-holed, cable car tracked >>> streets. >>> >>> >>> * convention is that you go >>> trailing-leading-leading-trailing when looking at the four >>> hub sides, theory being that this allows the spokes with >>> increasing tension from drive torque to distort the wheel's >>> dish less. with a disk braked rear, if you're following >>> this principle, you need to lace >>> leading-trailing-leading-trailing because braking reaction >>> opposes drive torque. it's a little more complicated to >>> lace, but it's specified in the shimano hub manual. >>> >>> >> >> Good overview. >> That rear spoking pattern for disc/drum rears is also the preferered >> 'old guy' way for fronts, which need no particular bias. > thanks for the comprehensive wrapup, took the time to setup thunderbird w eternal september again so I can crosspost at will ;-) My CXP-33 is laced over-4 whatever that means and the ceramic open pro is over-3 not sure how that meshes with leading-trailing-leading-trailing and trailing-leading-leading-trailing For next year cross competition I wonder if I'd reuse my roadbike to get a 26"er or 29"er. Though the latter is a bit too portly for competitions, I think > interesting. > > in that vein, old guys used to tie and solder. jobst went out of his way > to pour scorn on that practice, but doesn't do it in what is an actually > scientific way, just a pseudo-scientific way - i.e. the scientific way > is "objective, methods, results, conclusions". he just leaps from method > to conclusions, omitting actual results. yet he blithely accepts spoke > interleaving as "stabilizing the spoke structure" with no analysis > whatsoever. > > [i know, broken record, but i really can't understand why other people > don't see this stuff when reading - you don't need to be an engineer to > have logical inconsistency slap you in the face.] it's the "blond gene". you don't have to understand it, just accept "as is" |
#26
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engine onnatop placement implications
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#27
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engine onnatop placement implications
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#28
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engine onnatop placement implications
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#29
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engine onnatop placement implications
On Saturday, September 7, 2013 2:10:56 AM UTC+3, jim beam wrote:
> On 09/06/2013 08:33 AM, AMuzi wrote: > > > On 9/6/2013 9:17 AM, jim beam wrote: > > >> On 09/06/2013 02:19 AM, wrote: > > >>>>>> > > >>>>>> unfortunately, i don't think there's any one magic > > >>>>>> bullet on > > >>>>>> wheel building books. jobst's book will allow you to > > >>>>>> calculate spoke length from first principles [although, > > >>>>>> not > > >>>>>> allow for the elongation that happens as they tension], > > >>>>>> lace, true and tension, but it'll also have you > > >>>>>> over-tension, bend spokes unnecessarily, and he gives > > >>>>>> you a > > >>>>>> very iffy "stress relief" method. you'll also have no > > >>>>>> initial clue on how to position a hub so the label aligns > > >>>>>> with the valve hole, as per conventional practice. > > >>>>>> > > >>>>>> gerdt schraner's book will solve the hub label position > > >>>>>> problem, and have you stress relieve better, but you'll be > > >>>>>> reliant on others for spoke length. his lacing method is > > >>>>>> also unnecessarily complicated. > > >>>>>> > > >>>>>> sheldon brown's online guide is very good on lacing, hub > > >>>>>> positioning, but repeats a lot of the garbage that jobst > > >>>>>> bullied into him. and his stress relief method blows > > >>>>>> chunks. > > >>>>>> > > >>>>>> if you can find it online, the mavic wheelbuilding > > >>>>>> guide is > > >>>>>> pretty good. absolutely the best stress relief method. but > > >>>>>> it tells you nothing about spoke length calculation, > > >>>>>> presumably because if you're rebuilding a mavic wheel, > > >>>>>> you're already using spokes of predetermined length. > > >>>>>> > > >>>>>> so, "don't read that book in isolation" is my advice. and > > >>>>>> if you're thinking you want to understand wheel mechanics > > >>>>>> and don't already have a strong understanding of > > >>>>>> mechanical > > >>>>>> principles and materials, it'll badly **** you up > > >>>>>> because a > > >>>>>> lot of what he says is just plain wrong. > > >>>>>> > > >>>>>> as to building wheels for yourself, we've discussed this > > >>>>>> before. there are definitely benefits to learning in that > > >>>>>> most people don't have access to a good builder. > > >>>>>> statistically, that includes you. once you can build > > >>>>>> yourself, and you take the time to do it right, which most > > >>>>>> shops seldom invest, you can have a wheel that remains > > >>>>>> true > > >>>>>> and stable almost indefinitely. that's a rare beastie in > > >>>>>> "other people built" wheels. my mtb wheels, complete with > > >>>>>> unconventional rear spoking pattern*, have remained > > >>>>>> completely true despite some fearful abuse. same for my > > >>>>>> townie fixie on san fran's pot-holed, cable car tracked > > >>>>>> streets. > > >>>>>> > > >>>>>> > > >>>>>> * convention is that you go > > >>>>>> trailing-leading-leading-trailing when looking at the four > > >>>>>> hub sides, theory being that this allows the spokes with > > >>>>>> increasing tension from drive torque to distort the > > >>>>>> wheel's > > >>>>>> dish less. with a disk braked rear, if you're following > > >>>>>> this principle, you need to lace > > >>>>>> leading-trailing-leading-trailing because braking reaction > > >>>>>> opposes drive torque. it's a little more complicated to > > >>>>>> lace, but it's specified in the shimano hub manual. > > >>>>>> > > >>>>>> > > >>>>> > > >>>>> Good overview. > > >>>>> That rear spoking pattern for disc/drum rears is also > > >>>>> the preferered > > >>>>> 'old guy' way for fronts, which need no particular bias. > > >>>> > > >>> > > >>> > > >>> thanks for the comprehensive wrapup, > > >>> took the time to setup thunderbird w eternal september > > >>> again so I can > > >>> crosspost at will ;-) > > >>> > > >>> My CXP-33 is laced over-4 whatever that means and the > > >>> ceramic open pro > > >>> is over-3 > > >> > > >> "three cross" is conventional with an open pro. "4x" on a > > >> cxp33 is not something i'd do because it's not got as much > > >> socket angle available as the open pro - which is precisely > > >> what "4x" requires. i'd therefore expect spokes to be more > > >> likely to break at the threads. > > >> > > >> presumably the builder was looking to make the cxp33 a > > >> slightly "softer" ride - the cxp33 is very deep and thus > > >> rigid so it can ride "harsh" compared to others. ["4x" > > >> spokes are longer and thus theoretically slightly more > > >> elastic.] i'd have gone with a lower spoke count and "2x" > > >> personally. > > >> > > >> > > >> [another criticism of "the book" - jobst has succeeded in > > >> making most people think of "spoke crossing count" as one of > > >> the parameters for spoke length calculation. this is > > >> somewhat misleading since you can compute a result for > > >> 2.7179 "crossings", even though no such thing is possible. > > >> the fact is, the "crossing" number is in fact the number of > > >> hub hole offsets from the "key" position, and this doesn't > > >> have to be an integer.] > > >> > > >> > > >>> not sure how that meshes with > > >>> leading-trailing-leading-trailing > > >>> and trailing-leading-leading-trailing > > >> > > >> doesn't for "crossing" count. > > >> > > >> > > >>> > > >>> For next year cross competition I wonder if I'd reuse my > > >>> roadbike > > >>> to get a 26"er or 29"er. Though the latter is a bit too > > >>> portly > > >>> for competitions, I think > > >>> > > >>> > > >>>> interesting. > > >>>> > > >>>> in that vein, old guys used to tie and solder. jobst went > > >>>> out of his way > > >>>> to pour scorn on that practice, but doesn't do it in what > > >>>> is an actually > > >>>> scientific way, just a pseudo-scientific way - i.e. the > > >>>> scientific way > > >>>> is "objective, methods, results, conclusions". he just > > >>>> leaps from method > > >>>> to conclusions, omitting actual results. yet he blithely > > >>>> accepts spoke > > >>>> interleaving as "stabilizing the spoke structure" with no > > >>>> analysis > > >>>> whatsoever. > > >>>> > > >>>> [i know, broken record, but i really can't understand why > > >>>> other people > > >>>> don't see this stuff when reading - you don't need to be > > >>>> an engineer to > > >>>> have logical inconsistency slap you in the face.] > > >>> > > >>> it's the "blond gene". you don't have to understand it, > > >>> just accept "as is" > > >> > > >> cringe. > > >> > > >> > > > > > > Not enough information. > > > > > > 4x 48 spokes builds to an optimal spoke angle. 4x 40h is good, better > > > than 3x. > > > 4x with 32h is a clusterf**k. 4x 36 is failure prone, far from ideal, > > > not recommended. And yet guys do it with 50-50 results, despite our > > > admonition. > 4x36 was developing figure8th before I changed the wheelbuilder and last guy apparently did a faitly good job, that or I haven't ridden long enough after the last rebuild > > > indeed. so as we know the rim is cxp33, 4x is inappropriate given that > > it's either 28 or 32 hole. > it is a 36 hole cxp-33 I could recount the spokes but I belive I did ask for 36 and that's what I got. In fact the open pro is similarly overbuilt being 36-holy (but cross 2) can't get cxp-33 in 40 or 48 hole versions. I think. for 40 or 48 I guess I'd have to get some sort of a touring rim not that it's a bad thing since I value reliability over weight/speed what are my options for mtb rims in 26" and 28" in 40 or 48? (if any) |
#30
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engine onnatop placement implications
On Friday, September 6, 2013 6:33:48 PM UTC+3, AMuzi wrote:
> On 9/6/2013 9:17 AM, jim beam wrote: > > > On 09/06/2013 02:19 AM, wrote: > > >>>>> > > >>>>> unfortunately, i don't think there's any one magic > > >>>>> bullet on > > >>>>> wheel building books. jobst's book will allow you to > > >>>>> calculate spoke length from first principles [although, > > >>>>> not > > >>>>> allow for the elongation that happens as they tension], > > >>>>> lace, true and tension, but it'll also have you > > >>>>> over-tension, bend spokes unnecessarily, and he gives > > >>>>> you a > > >>>>> very iffy "stress relief" method. you'll also have no > > >>>>> initial clue on how to position a hub so the label aligns > > >>>>> with the valve hole, as per conventional practice. > > >>>>> > > >>>>> gerdt schraner's book will solve the hub label position > > >>>>> problem, and have you stress relieve better, but you'll be > > >>>>> reliant on others for spoke length. his lacing method is > > >>>>> also unnecessarily complicated. > > >>>>> > > >>>>> sheldon brown's online guide is very good on lacing, hub > > >>>>> positioning, but repeats a lot of the garbage that jobst > > >>>>> bullied into him. and his stress relief method blows > > >>>>> chunks. > > >>>>> > > >>>>> if you can find it online, the mavic wheelbuilding > > >>>>> guide is > > >>>>> pretty good. absolutely the best stress relief method. but > > >>>>> it tells you nothing about spoke length calculation, > > >>>>> presumably because if you're rebuilding a mavic wheel, > > >>>>> you're already using spokes of predetermined length. > > >>>>> > > >>>>> so, "don't read that book in isolation" is my advice. and > > >>>>> if you're thinking you want to understand wheel mechanics > > >>>>> and don't already have a strong understanding of > > >>>>> mechanical > > >>>>> principles and materials, it'll badly **** you up > > >>>>> because a > > >>>>> lot of what he says is just plain wrong. > > >>>>> > > >>>>> as to building wheels for yourself, we've discussed this > > >>>>> before. there are definitely benefits to learning in that > > >>>>> most people don't have access to a good builder. > > >>>>> statistically, that includes you. once you can build > > >>>>> yourself, and you take the time to do it right, which most > > >>>>> shops seldom invest, you can have a wheel that remains > > >>>>> true > > >>>>> and stable almost indefinitely. that's a rare beastie in > > >>>>> "other people built" wheels. my mtb wheels, complete with > > >>>>> unconventional rear spoking pattern*, have remained > > >>>>> completely true despite some fearful abuse. same for my > > >>>>> townie fixie on san fran's pot-holed, cable car tracked > > >>>>> streets. > > >>>>> > > >>>>> > > >>>>> * convention is that you go > > >>>>> trailing-leading-leading-trailing when looking at the four > > >>>>> hub sides, theory being that this allows the spokes with > > >>>>> increasing tension from drive torque to distort the > > >>>>> wheel's > > >>>>> dish less. with a disk braked rear, if you're following > > >>>>> this principle, you need to lace > > >>>>> leading-trailing-leading-trailing because braking reaction > > >>>>> opposes drive torque. it's a little more complicated to > > >>>>> lace, but it's specified in the shimano hub manual. > > >>>>> > > >>>>> > > >>>> > > >>>> Good overview. > > >>>> That rear spoking pattern for disc/drum rears is also > > >>>> the preferered > > >>>> 'old guy' way for fronts, which need no particular bias. > > >>> > > >> > > >> > > >> thanks for the comprehensive wrapup, > > >> took the time to setup thunderbird w eternal september > > >> again so I can > > >> crosspost at will ;-) > > >> > > >> My CXP-33 is laced over-4 whatever that means and the > > >> ceramic open pro > > >> is over-3 > > > > > > "three cross" is conventional with an open pro. "4x" on a > > > cxp33 is not something i'd do because it's not got as much > > > socket angle available as the open pro - which is precisely > > > what "4x" requires. i'd therefore expect spokes to be more > > > likely to break at the threads. > > > > > > presumably the builder was looking to make the cxp33 a > > > slightly "softer" ride - the cxp33 is very deep and thus > > > rigid so it can ride "harsh" compared to others. ["4x" > > > spokes are longer and thus theoretically slightly more > > > elastic.] i'd have gone with a lower spoke count and "2x" > > > personally. > Maybe I have cross 2 in front and cross 3 in the back. Tell me how to count and I'll tell for sure :^) I wanted higher rigidity for the rear to I asked for higher cross count for the rear wheel. To tell the truth it's probably an overkill for the amount of power I deliver to the wheel anyway, but ferrari owners don't use even half of the capacity also. So what the heck. |
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