It is impossible to overhaul, or even repair a dreaileur while it is attached to a bike that is sitting on the ground (especially for professional mechanics). If you hoist the bike, upright, into a purpose-built work stand you will find that the bike practically repairs itself.
> It is impossible to overhaul, or even repair a dreaileur while it is > attached to a bike that is sitting on the ground (especially for > professional mechanics). If you hoist the bike, upright, into a > purpose-built work stand you will find that the bike practically > repairs itself.
It's been sitting on a wall mounted bike rack for weeks now, and the damn thing still isn't running! :-)
It would be nice to have a work stand, but other things are occupying that spot in my budget right now.
> > Dear Zeppo: If I understand you correctly, you get a lot of satisfaction > > from making something work, in spite of the fact that you may be earning > > only 10 cents an hour for the effort. You cannot put a price on the > > satisfaction in making something work after it might have been > > "condemned." Keep at it.
> Thanks Leo. It is a kick bringing something 'back from the dead'. But it's > also a chance to bond with my teenage son. As he's > now a freshman in college, those moments are getting few and far between. > He's living at school, but close enough to hop the > regional rail to spend a day at home working on his new bike with his dad. > Devious, but it works.
> So I was able to confirm the rear derailleur is fine. I didn't have time > last night to play with the front (World Series) but I'll look at it > tonight. > However, the front is very corroded and pitted and might give me more piece > of mind to replace it anyway. We'll see. I'm picking up new brake > and derailleur cables on the way home this evening.
The rather extreme upside to all of this is that you get to fiddle on something that, should it break, won't set you back more than a Hamilton or so.
On Tue, 03 Nov 2009 10:54:42 -0500, Zeppo wrote: >> Err, if this is for son, why isn't he doing it?
> He is helping out, when he's home.
good to hear.
> He might not normally make this much 'together' time with Dad, but he's > liking the idea of having a bike on campus. As campus is in North > Philly, having a beat-up, rusting but serviceable bike is a big plus.
LBS owner sobbed when he saw the paint job I had applied to a brand new shiny quality bike frame I purchased of him. Really crappy job, but it stopped the bike being nicked for the four years I was at uni.
>> Looking to rebuild an old mountain bike someone gave us for my son to use >> at >> college. He is at an inner city campus so the condition of the bike (beat >> up, some rust, flaking paint) is a distinct advantage. The bike was left >> outdoors for the last year and is in pretty bad shape. It's a 2001 >> Performance M207 mountain bike.
>> I cleaned up the tires, replaced the tunes, brake pads and chain. The >> derailleurs seem to be frozen as were the idler pulleys on the rear. I >> was >> able to disassemble the pulleys and clean them up and they are OK now.
>> How tough is it to rebuild the derailleurs? I adjusted them before but >> have >> never taken one apart. Are there decent instructions somewhere on the web >> you could point me too? A Google search hasn't turned up anything useful >> yet. Would it be more cost effective to look for a used set on eBay and >> just >> replace them? I don't have a ton of cash to put into this (2 kids in >> college) so I'm looking to tap the wealth of your experience.
>> Thanks in advance for any help you can give.
> I could suggest you post the make and model of the derailleurs. That > might help.
> When you say frozen. Where? They don't move when you shift them or you > cant even move them by hand?
OK, so the cables are definitely shot and 2 days in WD-40 hasn't helped the front derailleur at all. It moves, but grudgingly, and not the full range. It's really corroded. The adjustment screws are pretty much rusted off.
The derailleur is a Shimano STX-RC, Model FD-MC38, a top-pull, top-swing model that fits a 31.8 tube.
> >> Looking to rebuild an old mountain bike someone gave us for my son to use > >> at > >> college. He is at an inner city campus so the condition of the bike (beat > >> up, some rust, flaking paint) is a distinct advantage. The bike was left > >> outdoors for the last year and is in pretty bad shape. It's a 2001 > >> Performance M207 mountain bike.
> >> I cleaned up the tires, replaced the tunes, brake pads and chain. The > >> derailleurs seem to be frozen as were the idler pulleys on the rear. I > >> was > >> able to disassemble the pulleys and clean them up and they are OK now.
> >> How tough is it to rebuild the derailleurs? I adjusted them before but > >> have > >> never taken one apart. Are there decent instructions somewhere on the web > >> you could point me too? A Google search hasn't turned up anything useful > >> yet. Would it be more cost effective to look for a used set on eBay and > >> just > >> replace them? I don't have a ton of cash to put into this (2 kids in > >> college) so I'm looking to tap the wealth of your experience.
> >> Thanks in advance for any help you can give.
> > I could suggest you post the make and model of the derailleurs. That > > might help.
> > When you say frozen. Where? They don't move when you shift them or you > > cant even move them by hand?
> OK, so the cables are definitely shot and 2 days in WD-40 hasn't helped the > front derailleur at all. It moves, but grudgingly, and not the full range. > It's really corroded. The adjustment screws are pretty much rusted off.
> The derailleur is a Shimano STX-RC, Model FD-MC38, a top-pull, top-swing > model that fits a 31.8 tube.
> Can you suggest a low cost replacement for this?
> Thanks, > Jon
Your original is likely to be the best choice. I've never seen a front der in a condition from non accidental causes where it cannot be revived. I would dunk it in diesel for 48 hours, mount it on a pole/ tube and scrub it with the head of a yard brush. Dont touch the limit screws, they're likely set right and its best not to move them unless necessary after full cleaning. after brushing swill it in clean fuel/ kerosene and oil it generously. Leave it for a day, then actuate it.
> >> Looking to rebuild an old mountain bike someone gave us for my son to use > >> at > >> college. He is at an inner city campus so the condition of the bike (beat > >> up, some rust, flaking paint) is a distinct advantage. The bike was left > >> outdoors for the last year and is in pretty bad shape. It's a 2001 > >> Performance M207 mountain bike.
> >> I cleaned up the tires, replaced the tunes, brake pads and chain. The > >> derailleurs seem to be frozen as were the idler pulleys on the rear. I > >> was > >> able to disassemble the pulleys and clean them up and they are OK now.
> >> How tough is it to rebuild the derailleurs? I adjusted them before but > >> have > >> never taken one apart. Are there decent instructions somewhere on the web > >> you could point me too? A Google search hasn't turned up anything useful > >> yet. Would it be more cost effective to look for a used set on eBay and > >> just > >> replace them? I don't have a ton of cash to put into this (2 kids in > >> college) so I'm looking to tap the wealth of your experience.
> >> Thanks in advance for any help you can give.
> > I could suggest you post the make and model of the derailleurs. That > > might help.
> > When you say frozen. Where? They don't move when you shift them or you > > cant even move them by hand?
> OK, so the cables are definitely shot and 2 days in WD-40 hasn't helped the > front derailleur at all. It moves, but grudgingly, and not the full range. > It's really corroded. The adjustment screws are pretty much rusted off.
> The derailleur is a Shimano STX-RC, Model FD-MC38, a top-pull, top-swing > model that fits a 31.8 tube.
> Can you suggest a low cost replacement for this?
Almost all front derailleurs are low cost. Find some that fit, and see. Sorry, I cannot recommend a specific model.
>> >> Looking to rebuild an old mountain bike someone gave us for my son to >> >> use >> >> at >> >> college. He is at an inner city campus so the condition of the bike >> >> (beat >> >> up, some rust, flaking paint) is a distinct advantage. The bike was >> >> left >> >> outdoors for the last year and is in pretty bad shape. It's a 2001 >> >> Performance M207 mountain bike.
>> >> I cleaned up the tires, replaced the tunes, brake pads and chain. The >> >> derailleurs seem to be frozen as were the idler pulleys on the rear. I >> >> was >> >> able to disassemble the pulleys and clean them up and they are OK now.
>> >> How tough is it to rebuild the derailleurs? I adjusted them before but >> >> have >> >> never taken one apart. Are there decent instructions somewhere on the >> >> web >> >> you could point me too? A Google search hasn't turned up anything >> >> useful >> >> yet. Would it be more cost effective to look for a used set on eBay >> >> and >> >> just >> >> replace them? I don't have a ton of cash to put into this (2 kids in >> >> college) so I'm looking to tap the wealth of your experience.
>> >> Thanks in advance for any help you can give.
>> > I could suggest you post the make and model of the derailleurs. That >> > might help.
>> > When you say frozen. Where? They don't move when you shift them or you >> > cant even move them by hand?
>> OK, so the cables are definitely shot and 2 days in WD-40 hasn't helped >> the >> front derailleur at all. It moves, but grudgingly, and not the full >> range. >> It's really corroded. The adjustment screws are pretty much rusted off.
>> The derailleur is a Shimano STX-RC, Model FD-MC38, a top-pull, top-swing >> model that fits a 31.8 tube.
>> Can you suggest a low cost replacement for this?
> Almost all front derailleurs are low cost. > Find some that fit, and see. > Sorry, I cannot recommend a specific model.
> -- > Michael Press
Not a problem Michael. From what I've been reading almost any top-pull derailleur that will fit the seat tube can be made to work. I picked up one on eBay for $10 that will do fine. Same configuration, just a newer model.
>> >> How tough is it to rebuild the derailleurs? I adjusted them before but >> >> have >> >> never taken one apart. Are there decent instructions somewhere on the >> >> web >> >> you could point me too? A Google search hasn't turned up anything >> >> useful >> >> yet. Would it be more cost effective to look for a used set on eBay >> >> and >> >> just >> >> replace them? I don't have a ton of cash to put into this (2 kids in >> >> college) so I'm looking to tap the wealth of your experience.
>> >> Thanks in advance for any help you can give.
>> > I could suggest you post the make and model of the derailleurs. That >> > might help.
>> > When you say frozen. Where? They don't move when you shift them or you >> > cant even move them by hand?
>> OK, so the cables are definitely shot and 2 days in WD-40 hasn't helped >> the >> front derailleur at all. It moves, but grudgingly, and not the full >> range. >> It's really corroded. The adjustment screws are pretty much rusted off.
>> The derailleur is a Shimano STX-RC, Model FD-MC38, a top-pull, top-swing >> model that fits a 31.8 tube.
>> Can you suggest a low cost replacement for this?
>> Thanks, >> Jon
> Your original is likely to be the best choice. I've never seen a > front der in a condition from non accidental causes where it cannot be > revived. I would dunk it in diesel for 48 hours, mount it on a pole/ > tube and scrub it with the head of a yard brush. Dont touch the limit > screws, they're likely set right and its best not to move them unless > necessary after full cleaning. after brushing swill it in clean fuel/ > kerosene and oil it generously. Leave it for a day, then actuate it.
I soaked it in WD-40 for a few days and that didn't loosen it up. Then 2 days in diesel, and it still wouldn't loosen. Picked up a used Shimano STX on eBay.
> >> >> How tough is it to rebuild the derailleurs? I adjusted them before but > >> >> have > >> >> never taken one apart. Are there decent instructions somewhere on the > >> >> web > >> >> you could point me too? A Google search hasn't turned up anything > >> >> useful > >> >> yet. Would it be more cost effective to look for a used set on eBay > >> >> and > >> >> just > >> >> replace them? I don't have a ton of cash to put into this (2 kids in > >> >> college) so I'm looking to tap the wealth of your experience.
> >> >> Thanks in advance for any help you can give.
> >> > I could suggest you post the make and model of the derailleurs. That > >> > might help.
> >> > When you say frozen. Where? They don't move when you shift them or you > >> > cant even move them by hand?
> >> OK, so the cables are definitely shot and 2 days in WD-40 hasn't helped > >> the > >> front derailleur at all. It moves, but grudgingly, and not the full > >> range. > >> It's really corroded. The adjustment screws are pretty much rusted off.
> >> The derailleur is a Shimano STX-RC, Model FD-MC38, a top-pull, top-swing > >> model that fits a 31.8 tube.
> >> Can you suggest a low cost replacement for this?
> >> Thanks, > >> Jon
> > Your original is likely to be the best choice. I've never seen a > > front der in a condition from non accidental causes where it cannot be > > revived. I would dunk it in diesel for 48 hours, mount it on a pole/ > > tube and scrub it with the head of a yard brush. Dont touch the limit > > screws, they're likely set right and its best not to move them unless > > necessary after full cleaning. after brushing swill it in clean fuel/ > > kerosene and oil it generously. Leave it for a day, then actuate it.
> I soaked it in WD-40 for a few days and that didn't loosen it up. Then 2 > days in diesel, and it still wouldn't loosen. Picked up a used Shimano STX > on eBay.
> Many thanks for you help.
> Jon
Did you not try to persuade it first? Pry bar, lump hammer, etc.
This subject runs into a common failure from which many bicycle components suffer, which is dissimilar metals exposed to corrosive fluids like sweat and rain-and-sweat. For example, classically quill stems fail preeminently from this because they are poorly designed, because the stem is retained by expanding in the steertube at its bottom end, allowing the upper end to sway from side-to-side. Fortunately, we have threadless steertubes today so this problem belongs to out fathers.
Aluminum head bearing shells have similar problems as do aluminum derailleurs on steel (chromed) pivots. Once aluminum oxide has frozen the parts in place, frame builders generally saw off the offending component, bore out the shaft to a thin walled shell and use a Dremel tool to cut it down one side to pull it out. Solvents do not dissolve aluminum oxide adequately to free the part and especially enough to make it work again.
I have pictures and collections of such parts, bu the bicycle industry is exceedingly slow to recognize the failure and how to fix it. As you see the threadless steer tube did it so but left hand BB (right cup) and pedal threads remain a point of failure. Left hand pedal threads have been explained here at length but the manufacturers don't seem to read or comprehend what appears here.
Wherever you find a left hand thread that is not part of a turnbuckle, you are looking at a faulty design. Threads are intended to hold parts together, not to support radial loads, something they cannot properly do. Bicycle companies have not discovered that because they don't hire qualified engineers, believing a bicycle is an inexpensive and simple device.
Likewise, after years of repairing failed inner tube patch failures and teaching riders how to avoid it is similarly useless, as we see from the responses in the tire patch threads. Although bicycle shops sell "the Bicycle Wheel" they generally avoid reading it, so customers know more about wheels than the mechanics who build them.
Science is a strange field, as we have seen in the "hot water freezes faster than cold water" thread that we had here recently. That story is ultra ancient and all my explanations never make it to the reader. It reminds me of "how do you ride a bicycle on a frozen lake?":
On Nov 11, 1:21 pm, Jobst Brandt <jbra...@sonic.net> wrote:
> Wherever you find a left hand thread that is not part of a turnbuckle, > you are looking at a faulty design. Threads are intended to hold > parts together, not to support radial loads, something they cannot > properly do.
Do you deem the left hand thread on the arbor of a radial arm saw to be a faulty design?
On Nov 11, 2:21 pm, Jobst Brandt <jbra...@sonic.net> wrote:
> Science is a strange field, as we have seen in the "hot water freezes > faster than cold water" thread that we had here recently. That story > is ultra ancient and all my explanations never make it to the reader.
Dear Jobst,
Dunno what you think is "recently" or what your "explanations" were.
Heck, I can't even tell from your post what you think.
Tom Ace wrote: >> Wherever you find a left hand thread that is not part of a >> turnbuckle, you are looking at a faulty design. Threads are >> intended to hold parts together, not to support radial loads, >> something they cannot properly do. > Do you deem the left hand thread on the arbor of a radial arm saw to > be a faulty design?
I don't have one of those so I cannot inspect its function. A turnbuckle is an adjustment device that works under pure tension. If that is what your saw does, it passes the test, while the left hand thread on a left pedal, a right BB cup or an old fashioned auto lug nut on left side wheels do not. Re-read (>>) the statement above and I think you will see whether your saw uses threads correctly.
I don't see where this is ambiguous. You must have missed the thread on left hand bicycle pedal crank failures and why they occur.
Carl Fogel wrote: >> Science is a strange field, as we have seen in the "hot water >> freezes faster than cold water" thread that we had here >> recently. That story is ultra ancient and all my explanations >> never make it to the reader. > Dunno what you think is "recently" or what your "explanations" were. > Heck, I can't even tell from your post what you think. > But for anyone curious:
You needn't be so condescending, the cause for the more rapid freezing of warm water than for cold water is insulation, especially in pipes where there is no evaporation. I explained how hot water makes the glass clear ice cubes one gets at soft drink dispensers, while whitish ice, made in one's home refrigerator from cold water is white with entrapped air that insulates. The "Mpemba Effect" is a hoax, as are many other such "discoveries".
I am disappointed in Wikipedia for that one.
> It's a widely observed and measured effect, with most suggested > explanations involving flaws in the experiments ruled out in the > original paper.
Hot (mostly devoid of entrapped air) water pipes burst sooner than cold (aerated) water pipes, but they both burst from freezing water. Also a widely observed effect. Let's put the cause where it belongs not on folklore. Just because someone with an oddly spelled name writes an unsupported paper doesn't make it a fact.
>>> Wherever you find a left hand thread that is not part of a >>> turnbuckle, you are looking at a faulty design. Threads are >>> intended to hold parts together, not to support radial loads, >>> something they cannot properly do.
>> Do you deem the left hand thread on the arbor of a radial arm saw to >> be a faulty design?
> I don't have one of those so I cannot inspect its function. A > turnbuckle is an adjustment device that works under pure tension. If > that is what your saw does, it passes the test, while the left hand > thread on a left pedal, a right BB cup or an old fashioned auto lug > nut on left side wheels do not. Re-read (>>) the statement above and > I think you will see whether your saw uses threads correctly.
> I don't see where this is ambiguous. You must have missed the thread > on left hand bicycle pedal crank failures and why they occur.
> Jobst Brandt
Saws, grinding wheels, etc. all tend to have left hand threads where the rotation of the blade/wheel will tend to tighten the arbor nut and not loosen it. e.g. my bench grinder has a RH thread on the right side and a LH thread on the left side (the shaft rotates counterclockwise as you look at it end on from the RH side, so the faces of the wheels are moving down as you face it.) I really can't imagine it being any other way; otherwise whenever you developed any significant torque on the LH wheel it would loosen the nut.
Carl Fogel wrote: >> Science is a strange field, as we have seen in the "hot water freezes >> faster than cold water" thread that we had here recently. That story >> is ultra ancient and all my explanations never make it to the reader. > Dunno what you think is "recently" or what your "explanations" were. > Heck, I can't even tell from your post what you think.
For someone who searches the web for minutia and offers links to them, you are trying hard to be disparaging in your reply instead of addressing the subject. I hope you construe further responses to clarifying the subject rather than ridiculing others.
This is beginning to sound like a jim beam exchange.
Nate Nagel wrote: >>>> Wherever you find a left hand thread that is not part of a >>>> turnbuckle, you are looking at a faulty design. Threads are >>>> intended to hold parts together, not to support radial loads, >>>> something they cannot properly do. >>> Do you deem the left hand thread on the arbor of a radial arm saw >>> to be a faulty design? >> I don't have one of those so I cannot inspect its function. A >> turnbuckle is an adjustment device that works under pure tension. >> If that is what your saw does, it passes the test, while the left >> hand thread on a left pedal, a right BB cup or an old fashioned >> auto lug nut on left side wheels do not. Re-read (>>) the >> statement above and I think you will see whether your saw uses >> threads correctly. >> I don't see where this is ambiguous. You must have missed the >> thread on left hand bicycle pedal crank failures and why they >> occur. > Saws, grinding wheels, etc. all tend to have left hand threads where > the rotation of the blade/wheel will tend to tighten the arbor nut > and not loosen it. e.g. my bench grinder has a RH thread on the > right side and a LH thread on the left side (the shaft rotates > counterclockwise as you look at it end on from the RH side, so the > faces of the wheels are moving down as you face it.) I really can't > imagine it being any other way; otherwise whenever you developed any > significant torque on the LH wheel it would loosen the nut.
That's because they are, like bicycle pedals, doing what others have without proper analysis. You'll note that Shimano no longer transmits pedaling torque to the back wheel through screw-on sprockets because it was a horrible design. The same goes for saws and grinding wheels that are not properly located and tend to get tighter with torque.
That fits the description of a faulty design.
Have you noticed how small hyper-crackers are in comparison to chain whips to remove rear wheel sprockets? They are an example of improvement and a proper design.
On 3 Nov, 16:13, thirty-six <thirty-...@live.co.uk> wrote:
> If the cables are without the plastic tube between the inner wire and > outer spral wrap housing, then(sorry, lost it, feels like I'm > programming)
For cables without liners use a regular grade of oil or grease. The reliable long service method is to use graphited grease pumped in to the housing with a special applicator for bowden wires. The case of grease is warmed and a pump applied to pressurise the 'piston', the cable moved to and fro until the grease appears at the other end. It's a neat device if you can use it.
>>>>> Wherever you find a left hand thread that is not part of a >>>>> turnbuckle, you are looking at a faulty design. Threads are >>>>> intended to hold parts together, not to support radial loads, >>>>> something they cannot properly do.
>>>> Do you deem the left hand thread on the arbor of a radial arm saw >>>> to be a faulty design?
>>> I don't have one of those so I cannot inspect its function. A >>> turnbuckle is an adjustment device that works under pure tension. >>> If that is what your saw does, it passes the test, while the left >>> hand thread on a left pedal, a right BB cup or an old fashioned >>> auto lug nut on left side wheels do not. Re-read (>>) the >>> statement above and I think you will see whether your saw uses >>> threads correctly.
>>> I don't see where this is ambiguous. You must have missed the >>> thread on left hand bicycle pedal crank failures and why they >>> occur.
>> Saws, grinding wheels, etc. all tend to have left hand threads where >> the rotation of the blade/wheel will tend to tighten the arbor nut >> and not loosen it. e.g. my bench grinder has a RH thread on the >> right side and a LH thread on the left side (the shaft rotates >> counterclockwise as you look at it end on from the RH side, so the >> faces of the wheels are moving down as you face it.) I really can't >> imagine it being any other way; otherwise whenever you developed any >> significant torque on the LH wheel it would loosen the nut.
> That's because they are, like bicycle pedals, doing what others have > without proper analysis. You'll note that Shimano no longer transmits > pedaling torque to the back wheel through screw-on sprockets because > it was a horrible design. The same goes for saws and grinding wheels > that are not properly located and tend to get tighter with torque.
> That fits the description of a faulty design.
> Have you noticed how small hyper-crackers are in comparison to chain > whips to remove rear wheel sprockets? They are an example of > improvement and a proper design.
> Jobst Brandt
It may be inelegant, but "faulty" is a bit of a stretch... I've used bench grinders inherited from my great-grandfather that used the same design and managed to hold together all these years. (my dad has one bolted to a workbench into his barn that is likely older than he, although I think I replaced the motor sometime back when I was in high school, the grinder head just got a clean up and some fresh oil - it's a belt driven head so you can hide the motor under the bench and have more access to the wheels for odd shaped parts.)
I am trying to think of an alternative method (not using the rotation of the wheel to keep a nut tight) to keep the wheel from loosening its attachment mechanism without adding parts or complexity, and am coming up dry.
>>> Science is a strange field, as we have seen in the "hot water >>> freezes faster than cold water" thread that we had here >>> recently. That story is ultra ancient and all my explanations >>> never make it to the reader.
>> Dunno what you think is "recently" or what your "explanations" were.
>> Heck, I can't even tell from your post what you think.
>You needn't be so condescending, the cause for the more rapid freezing >of warm water than for cold water is insulation, especially in pipes >where there is no evaporation.
Dear Jobst,
Nope, two containers, same freezer, well-known phenomenon.
>>>>>> Wherever you find a left hand thread that is not part of a >>>>>> turnbuckle, you are looking at a faulty design. Threads are >>>>>> intended to hold parts together, not to support radial loads, >>>>>> something they cannot properly do.
>>>>> Do you deem the left hand thread on the arbor of a radial arm saw >>>>> to be a faulty design?
>>>> I don't have one of those so I cannot inspect its function. A >>>> turnbuckle is an adjustment device that works under pure tension. >>>> If that is what your saw does, it passes the test, while the left >>>> hand thread on a left pedal, a right BB cup or an old fashioned >>>> auto lug nut on left side wheels do not. Re-read (>>) the >>>> statement above and I think you will see whether your saw uses >>>> threads correctly.
>>>> I don't see where this is ambiguous. You must have missed the >>>> thread on left hand bicycle pedal crank failures and why they >>>> occur.
>>> Saws, grinding wheels, etc. all tend to have left hand threads where >>> the rotation of the blade/wheel will tend to tighten the arbor nut >>> and not loosen it. e.g. my bench grinder has a RH thread on the >>> right side and a LH thread on the left side (the shaft rotates >>> counterclockwise as you look at it end on from the RH side, so the >>> faces of the wheels are moving down as you face it.) I really can't >>> imagine it being any other way; otherwise whenever you developed any >>> significant torque on the LH wheel it would loosen the nut.
>> That's because they are, like bicycle pedals, doing what others have >> without proper analysis. You'll note that Shimano no longer transmits >> pedaling torque to the back wheel through screw-on sprockets because >> it was a horrible design. The same goes for saws and grinding wheels >> that are not properly located and tend to get tighter with torque.
>> That fits the description of a faulty design.
>> Have you noticed how small hyper-crackers are in comparison to chain >> whips to remove rear wheel sprockets? They are an example of >> improvement and a proper design.
>> Jobst Brandt
> It may be inelegant, but "faulty" is a bit of a stretch... I've used > bench grinders inherited from my great-grandfather that used the same > design and managed to hold together all these years. (my dad has one > bolted to a workbench into his barn that is likely older than he, > although I think I replaced the motor sometime back when I was in high > school, the grinder head just got a clean up and some fresh oil - it's a > belt driven head so you can hide the motor under the bench and have more > access to the wheels for odd shaped parts.)
> I am trying to think of an alternative method (not using the rotation of > the wheel to keep a nut tight) to keep the wheel from loosening its > attachment mechanism without adding parts or complexity, and am coming > up dry.
On 11 Nov 2009 21:21:32 GMT, Jobst Brandt <jbra...@sonic.net> wrote:
>I have pictures and collections of such parts, bu the bicycle industry >is exceedingly slow to recognize the failure and how to fix it. As >you see the threadless steer tube did it so but left hand BB (right >cup) and pedal threads remain a point of failure. Left hand pedal >threads have been explained here at length but the manufacturers don't >seem to read or comprehend what appears here.
>Wherever you find a left hand thread that is not part of a turnbuckle, >you are looking at a faulty design. Threads are intended to hold >parts together, not to support radial loads, something they cannot >properly do. Bicycle companies have not discovered that because they >don't hire qualified engineers, believing a bicycle is an inexpensive >and simple device.
More likely they understand it perfectly well but are uninterested in attempting to introduce a new standard that replaces pedals and crank arms. It doesn't matter how many of what kind of engineers they hire, they would first have to convince riders that there is a problem and that this is the solution. Then they get to convince buyers that they won't find themselves with an orphan crankset that no pedal will fit in five years.
Perhaps Shimano could pull this off. If they tried very hard and invested a huge amount of money. Nobody else has the breadth of pedal types and market levels to even think about it.
The threadless headset is simpler, less expensive and requires less labor to install than the system it replaces, regardless of its other advantages. That won't be true of your new pedal system.
> >>>>> Wherever you find a left hand thread that is not part of a > >>>>> turnbuckle, you are looking at a faulty design. Threads are > >>>>> intended to hold parts together, not to support radial loads, > >>>>> something they cannot properly do.
> >>>> Do you deem the left hand thread on the arbor of a radial arm saw > >>>> to be a faulty design?
> >>> I don't have one of those so I cannot inspect its function. A > >>> turnbuckle is an adjustment device that works under pure tension. > >>> If that is what your saw does, it passes the test, while the left > >>> hand thread on a left pedal, a right BB cup or an old fashioned > >>> auto lug nut on left side wheels do not. Re-read (>>) the > >>> statement above and I think you will see whether your saw uses > >>> threads correctly.
> >>> I don't see where this is ambiguous. You must have missed the > >>> thread on left hand bicycle pedal crank failures and why they > >>> occur.
> >> Saws, grinding wheels, etc. all tend to have left hand threads where > >> the rotation of the blade/wheel will tend to tighten the arbor nut > >> and not loosen it. e.g. my bench grinder has a RH thread on the > >> right side and a LH thread on the left side (the shaft rotates > >> counterclockwise as you look at it end on from the RH side, so the > >> faces of the wheels are moving down as you face it.) I really can't > >> imagine it being any other way; otherwise whenever you developed any > >> significant torque on the LH wheel it would loosen the nut.
> > That's because they are, like bicycle pedals, doing what others have > > without proper analysis. You'll note that Shimano no longer transmits > > pedaling torque to the back wheel through screw-on sprockets because > > it was a horrible design. The same goes for saws and grinding wheels > > that are not properly located and tend to get tighter with torque.
> > That fits the description of a faulty design.
> > Have you noticed how small hyper-crackers are in comparison to chain > > whips to remove rear wheel sprockets? They are an example of > > improvement and a proper design.
> > Jobst Brandt
> It may be inelegant, but "faulty" is a bit of a stretch... I've used > bench grinders inherited from my great-grandfather that used the same > design and managed to hold together all these years. (my dad has one > bolted to a workbench into his barn that is likely older than he, > although I think I replaced the motor sometime back when I was in high > school, the grinder head just got a clean up and some fresh oil - it's a > belt driven head so you can hide the motor under the bench and have more > access to the wheels for odd shaped parts.)
> I am trying to think of an alternative method (not using the rotation of > the wheel to keep a nut tight) to keep the wheel from loosening its > attachment mechanism without adding parts or complexity, and am coming > up dry.
Vibration will shake pretty much anything loose and that is why the screw fastening is the correct one.
On Nov 11, 2:39 pm, Jobst Brandt <jbra...@sonic.net> wrote:
> >> Wherever you find a left hand thread that is not part of a > >> turnbuckle, you are looking at a faulty design. Threads are > >> intended to hold parts together, not to support radial loads, > >> something they cannot properly do. > > Do you deem the left hand thread on the arbor of a radial arm saw to > > be a faulty design?
> I don't have one of those so I cannot inspect its function.
I can't imagine you haven't seen this kind of arrangement. Millions of saws in the USA use a threaded 5/8" arbor. A pic (with the nut loosened a bit) is at http://minortriad.com/rsaw.jpg
You said in another response that "The same goes for saws and grinding wheels that are not properly located and tend to get tighter with torque."
Tightening in use is a non-issue. The nut comes off with a short hand tool, with the same torque I put it on with.
If this is a faulty design, describe one that would be better. Keep in mind that it has to be able to mount one blade or a whole stack (for dado or rabbet joints).
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