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14-12.-2004, 03:34 AM
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#16 |
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Guest
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Re: A problem with gears.
dkahn400 wrote:
> OIC. You mean the rotation of the link itself as it passes over the > sprocket. I thought you were referring to rotations of the complete > chain. That's right, sorry I didn't make it clearer. It's the kind of thing I find difficult to put into words, but that doesn't stop me being interested in the subject :-) ~PB |
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14-12.-2004, 08:33 AM
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#17 |
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Re: A problem with gears.
Pete Biggs wrote: > James Annan wrote: > >>You've just had it demonstrated to you why dirt must the main factor: >>compare the stress of a loaded tandem riding big hills in clean dry >>roads, to an MTB in muddy areas. > > > Do the tandems have the same gears as the MTB's, or do they have larger > cogs? The chain has to rotate more on smaller sprockets, causing more > wear. > Basically the same, although there is certainly a tendency to smaller granny rings for touring and hills. 18T is not unheard-of. We also like a large big ring for flat roads, but that is not really relevant to the discussion. > I don't know how the stresses compare anyway. Serious off-roaders apply > serious amounts of torque. > Actually, most of whon you are considering as "serious off-roaders" are probably skinny midgets who exert rather low forces and use unusually high gears. A pair of lardy yanks carrying a tent hauling ass up a hill in their granny gear, now THAT is a serious amount of torque, even though they are going at walking speed! > Not convinvced it's mostly down to dirt yet, Nevertheless, it is. Obviously load will also have some effect too, but it can not explain the order-of-magnitude (and more) differences in wear that are routinely found between clean and dirty use. James -- If I have seen further than others, it is by treading on the toes of giants. http://www.ne.jp/asahi/julesandjames/home/ |
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14-12.-2004, 09:59 PM
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#18 |
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Guest
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Re: A problem with gears.
On Mon, 13 Dec 2004 20:36:20 +0900, James Annan
<still_the_same_me@hotmail.com> wrote: >Martin Wilson wrote: > > >> >> Personally I think your not firing on all >> cyclinders if you think load isn't a factor with regard chain and >> cassette wear even if its not the main factor but hopefully if you >> read some real world experiences you might think differently. > >Personally I think you're not firing on all cyclinders if you prefer to >make up some feeble straw man rather than just read what I said, which >was neither ambiguous nor inaccurate. > Make up some straw man? Never heard of this before and frankly don't know what your talking about. I've seen enough of loads effecting chain wear to know its a factor even if its not the main factor its still significant in many situations. To almost eliminate load from the formula for chain wear just seems highly illogical. You know yourself that if that the load kept increasing there would at least come a point where it was significant. The OP has high levels of wear on the sprocket most used that has the most load applied. The wear on the other sprockets is much, much lighter and from the sound of it almost non existant. I assume the same grit and dirt moves with the chain and goes round all the sprockets and not just the smallest. I don't know the percentage of how much the smallest rear sprocket is used compared to the other gears. I suspect quite high but theres possibly more chain/teeth contact in the lower gears at any one time. Obviously cadence is factor too. Surely though if load wasn't a factor the wear and tear of the chain and sprocket teeth would be more general across the whole range of cassette gears. |
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14-12.-2004, 11:05 PM
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#19 |
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Guest
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Re: A problem with gears.
"Martin Wilson" <martin.w6@ukonline.co.uk> wrote in message
news:5tjtr09m9977k0k8v5cnp5jc8d48qqksft@4ax.com... > The OP has high levels of wear on the sprocket most used that has > the most load applied. This is almost certainly not true - what you've diagnosed as wear is probably the original shape. This puts the rest of your argument out. cheers, clive |
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14-12.-2004, 11:24 PM
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#20 |
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Re: A problem with gears.
Martin Wilson wrote:
> On Mon, 13 Dec 2004 20:36:20 +0900, James Annan > <still_the_same_me@hotmail.com> wrote: > >Personally I think you're not firing on all cyclinders if you > >prefer to make up some feeble straw man rather than just read > >what I said, which was neither ambiguous nor inaccurate. > > Make up some straw man? Never heard of this before and frankly don't > know what your talking about. James is suggesting, I think, that the argument you refuted was not the one he was putting forward but rather a superficially similar one you set up just so you could knock it down. That's my understanding of a "straw man". Whether that's what you were actually doing I'll leave for the two of you to sort out. > The OP has high levels of wear on the sprocket most used that has > the most load applied. The wear on the other sprockets is much, > much lighter and from the sound of it almost non existant. I assume > the same grit and dirt moves with the chain and goes round all the > sprockets and not just the smallest. I don't know the percentage of > how much the smallest rear sprocket is used compared to the other > gears. I suspect quite high but theres possibly more chain/teeth > contact in the lower gears at any one time. Obviously cadence is > factor too. Surely though if load wasn't a factor the wear and tear > of the chain and sprocket teeth would be more general across the > whole range of cassette gears. In the OP's case the wear is greatest on the smallest sprocket because that's the one he uses most of the time. First the chain wears causing it to "stretch". Once it has stretched sprocket wear begins to accelerate. The more stretched the chain, the faster the sprocket wears. The sprockets that wear most are the ones that are used most. I've personally worn out 2 and 3 in a 6 sprocket cluster by continuing to use a stretched chain. 4 was less worn and 1 (the largest) and 5 and 6 (the smallest) were hardly worn at all. I believe distance covered is far more significant in this than either load or cadence. No matter what gear you are in each tooth of the engaged sprocket meshes with a chain link once per wheel revolution. The point about the larger sprockets having more teeth in contact with the chain is misleading, I think, because the stretched chain no longer meshes properly with the teeth; the load is concentrated on the top teeth until the sprocket has worn sufficiently to conform to the stretched chain. -- Dave... |
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14-12.-2004, 11:25 PM
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#21 |
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Guest
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Re: A problem with gears.
Martin Wilson wrote: > On Mon, 13 Dec 2004 20:36:20 +0900, James Annan > <still_the_same_me@hotmail.com> wrote: > > >>Martin Wilson wrote: >> >> >> >>>Personally I think your not firing on all >>>cyclinders if you think load isn't a factor with regard chain and >>>cassette wear even if its not the main factor but hopefully if you >>>read some real world experiences you might think differently. >> >>Personally I think you're not firing on all cyclinders if you prefer to >>make up some feeble straw man rather than just read what I said, which >>was neither ambiguous nor inaccurate. >> > > > Make up some straw man? Never heard of this before and frankly don't > know what your talking about. The straw man is your suggestion that I, or anyone else, is claiming that load is not a factor at all in chain and cassette wear. Of course it's _a_ factor (I have already written "I agree that in principle, increasing the load will increase the wear"), just a small one in comparison to how clean or dirty the chain is. As has now been explained to you several times over, with supporting evidence. James -- If I have seen further than others, it is by treading on the toes of giants. http://www.ne.jp/asahi/julesandjames/home/ |
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15-12.-2004, 04:54 AM
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#22 |
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Re: A problem with gears.
On Tue, 14 Dec 2004 11:59:16 +0000, Martin Wilson
<martin.w6@ukonline.co.uk> wrote in message <5tjtr09m9977k0k8v5cnp5jc8d48qqksft@4ax.com>: >Make up some straw man? Never heard of this before and frankly don't >know what your talking about. http://www.datanation.com/fallacies/index.htm Guy -- "then came ye chavves, theyre cartes girded wyth candels blue, and theyre beastes wyth straynge horn-lyke thyngs onn theyre arses that theyre fartes be herde from myles around." Chaucer, the Sheppey Tales |
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15-12.-2004, 07:58 AM
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#23 |
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Re: A problem with gears.
Martin Wilson wrote:
> I assume the same grit and dirt moves with the > chain and goes round all the sprockets and not just the smallest. I > don't know the percentage of how much the smallest rear sprocket is > used compared to the other gears. I suspect quite high but theres > possibly more chain/teeth contact in the lower gears at any one time. > Obviously cadence is factor too. Surely though if load wasn't a factor > the wear and tear of the chain and sprocket teeth would be more > general across the whole range of cassette gears. Grit on the sprocket will not actually wear it, this is not a corrosion effect. The wear comes when that grit is ground into the sprocket by the chain. It doesn't matter how much shite is on the other sprockets if the chain never touches them. Jon |
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15-12.-2004, 08:18 AM
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#24 |
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Re: A problem with gears.
Jon Senior wrote:
> Martin Wilson wrote: >> I assume the same grit and dirt moves with the >> chain and goes round all the sprockets and not just the smallest. I >> don't know the percentage of how much the smallest rear sprocket is >> used compared to the other gears. I suspect quite high but theres >> possibly more chain/teeth contact in the lower gears at any one time. >> Obviously cadence is factor too. Surely though if load wasn't a >> factor the wear and tear of the chain and sprocket teeth would be >> more general across the whole range of cassette gears. > > Grit on the sprocket will not actually wear it, this is not a > corrosion effect. The wear comes when that grit is ground into the > sprocket by the chain. It doesn't matter how much shite is on the > other sprockets if the chain never touches them. I think most sprocket wear is caused by chain elongation. The argument goes that grit within the chain wears it out and elongates it. ~PB |
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15-12.-2004, 07:56 PM
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#25 |
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Guest
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Re: A problem with gears.
On Mon, 13 Dec 2004 20:36:20 +0900, James Annan
<still_the_same_me@hotmail.com> wrote: >Martin Wilson wrote: > > >> >> Personally I think your not firing on all >> cyclinders if you think load isn't a factor with regard chain and >> cassette wear even if its not the main factor but hopefully if you >> read some real world experiences you might think differently. > >Personally I think you're not firing on all cyclinders if you prefer to >make up some feeble straw man rather than just read what I said, which >was neither ambiguous nor inaccurate. > >James So how exactly have I moved the goalposts to create this so called feeble straw man? All I've ever said is load is a factor, not the main factor but an important factor and obviously under certain conditions (extreme weight or gearing perhaps the major factor especially where a chain hasn't been well maintained). I've never argued against grit/dirt being a major factor. However there seems to be plenty of examples of people where load has been the main factor for them in excessive chain and sprocket wear and other sources where dirt and grit are the main factor. ">The chain almost certainly has stretched, but this has nothing to do >with the weight of the rider or the amount of hill climbing done." This statement clearly states that the writer does not perceive load to be a factor at all in chain roller wear. |
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15-12.-2004, 08:48 PM
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#26 |
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Guest
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Re: A problem with gears.
Martin Wilson wrote: > ">The chain almost certainly has stretched, but this has nothing to > > do with the weight of the rider or the amount of hill climbing > > done." > > This statement clearly states that the writer does not perceive load > to be a factor at all in chain roller wear. That was me, I think. I still don't believe that load is a significant factor in chain wear in normal bicycle riding. When the rollers are full of grinding paste (oil + grit) they will wear rapidly with any rider. If they are clean and lubricated inside they will wear much more slowly with any rider. -- Dave... |
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15-12.-2004, 10:55 PM
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#27 |
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Guest
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Re: A problem with gears.
dkahn400 wrote:
> Martin Wilson wrote: > >>">The chain almost certainly has stretched, but this has nothing to >> >>>do with the weight of the rider or the amount of hill climbing >>>done." >> >>This statement clearly states that the writer does not perceive load >>to be a factor at all in chain roller wear. > > > That was me, I think. I still don't believe that load is a significant > factor in chain wear in normal bicycle riding. When the rollers are > full of grinding paste (oil + grit) they will wear rapidly with any > rider. If they are clean and lubricated inside they will wear much more > slowly with any rider. > Load creates the normal force on the bearing surface. This is one the fundamental factors in determining wear rates. It's quite basic engineering knowledge. Look up "tribology" references. -- Joe * If I cannot be free I'll be cheap |
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15-12.-2004, 11:14 PM
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#28 |
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Guest
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Re: A problem with gears.
Martin Wilson wrote: > On Mon, 13 Dec 2004 20:36:20 +0900, James Annan > <still_the_same_me@hotmail.com> wrote: > > >>Martin Wilson wrote: >> >> >> >>>Personally I think your not firing on all >>>cyclinders if you think load isn't a factor with regard chain and >>>cassette wear even if its not the main factor but hopefully if you >>>read some real world experiences you might think differently. >> >>Personally I think you're not firing on all cyclinders if you prefer to >>make up some feeble straw man rather than just read what I said, which >>was neither ambiguous nor inaccurate. >> >>James > > > So how exactly have I moved the goalposts to create this so called > feeble straw man? By posting - as a follow-up to me - a message saying "I think your not firing on all cyclinders if you think load isn't a factor with regard chain and cassette wear" when not only had I not said such a thing, I had clearly stated that on the contrary I believe that load IS a factor. I know from my own experiences (not just reading about others) that tandem chains wear out faster than single bike chains under similar riding conditions. However, this very large difference in load still has a relatively small effect compared to the dirtiness of the chain, which can certainly cause a factor of 10 difference in life (even without going as far as enclosed oil baths or extremely dirty MTBing - I'm just talking about a fair weather rider who cleans the chain every time versus someone who rides on the road in all weather with minimal maintenance). James -- If I have seen further than others, it is by treading on the toes of giants. http://www.ne.jp/asahi/julesandjames/home/ |
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16-12.-2004, 01:46 AM
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#29 |
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Re: A problem with gears.
JLB wrote: > Load creates the normal force on the bearing surface. This is one the > fundamental factors in determining wear rates. It's quite basic > engineering knowledge. Look up "tribology" references. If there's no load the chain won't turn at all so there'll be no wear. Is that your point? -- Dave... |
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16-12.-2004, 03:13 AM
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#30 |
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Guest
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Re: A problem with gears.
dkahn400 wrote:
> JLB wrote: > > >>Load creates the normal force on the bearing surface. This is one the >>fundamental factors in determining wear rates. It's quite basic >>engineering knowledge. Look up "tribology" references. > > > If there's no load the chain won't turn at all so there'll be no wear. > Is that your point? You are missing the point. Perhaps you cannot visualise the forces on individual components of the chain that are moving in relation to one another. You wrote earlier "That was me, I think. I still don't believe that load is a significant factor in chain wear in normal bicycle riding. When the rollers are full of grinding paste (oil + grit) they will wear rapidly with any rider. If they are clean and lubricated inside they will wear much more slowly with any rider." The load is a *necessary* but *not* *sufficient* condition, and where bearing surfaces in relative motion make contact, wear rate will increase with increased load. Note also that where foreign particles like bits of grit are present, the contact points of the grit and the chain components is part of the bearing area; it is the area on which the load bears. The wear that occurs is due to huge local stresses, easily above the yield stress, acting on tiny areas of the components as the rough surfaces from earlier damage and bits of grit are pushed into and dragged across other surfaces. At a microscopic level the effect is like chisels digging into the metal surface. And of course the damage is related to the load; just as you cannot chisel chunks out of a block of wood unless you drive the chisel into the wood. Your statement "I still don't believe that load is a significant factor in chain wear" suggests you refuse to accept basic mechanical engineering knowledge. -- Joe * If I cannot be free I'll be cheap |
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