#21
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new chain, slack
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#22
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new chain, slack
Frank Krygowski wrote:
Chain wear happens inside the chain's pivots. The wear is on the pins, the rollers and any surface between them. The wear happens when the pivot is under tension and the two links connected by that pivot are either bending or straightening. OK...? Do you have a picture that illustrates this or at least identifies the parts refered to? I have this http://user.it.uu.se/~embe8573/bike/...erminology.jpg but "pivot" isn't mentioned... And how long should you be able to go before the slack exposes you a fraud mechanic and/or the owner of crooked gear? For derailleur bikes, many people recommend replacing a chain when it's worn (or "stretched") so it's one half percent longer than when new. (This is most easily measured with a ruler marked in inches. Do you have one of those?) Eheh... what's next, you going to ask Picasso if he has a brush? Of course I have folding rule, ruler, measuring tape, and calipers in inches as well as cm. But you have to remove the chain to do this, right? So it is not so fast after all. Even less so with a chain guard which is very common on these bikes. The method I use is: see if the chain is slack. If it is, move the wheel back. If it can't be done, get a new chain. Some people remove links but chains are so cheap anyway. -- underground experts united http://user.it.uu.se/~embe8573 |
#23
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new chain, slack
James wrote:
Is it possible the rear axle nuts were simply not done up quite tight enough and the axle slipped forward in the drop out slots? Well, yeah, maybe! Shimano says, somewhere (?), dome nuts or wheel axle nuts should be 28-32 Nm. I have my torque wrench permanently at 30 Nm as this is the only application I found so far, sadly -- underground experts united http://user.it.uu.se/~embe8573 |
#24
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new chain, slack
Frank Krygowski wrote:
This has a couple possible implications. Here's one: sprockets (especially chainrings on less expensive bikes) are seldom perfectly round. Usually you can notice the change in tension (i.e. change in visible slack) as you turn the cranks with the bike on a stand. I suppose it's possible that the first estimate of chain "tightness" happened with the chain on a high spot, the next one on a low spot. That's true! What spot should you choose, then? I always put the crank vertically, the one where I can pull the most. I haven't thought of the possibility of overstretching at the other end. But you have to pull really tight for that to happen, right? -- underground experts united http://user.it.uu.se/~embe8573 |
#25
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new chain, slack
On Friday, December 22, 2017 at 6:53:15 PM UTC-5, Emanuel Berg wrote:
Frank Krygowski wrote: Chain wear happens inside the chain's pivots. The wear is on the pins, the rollers and any surface between them. The wear happens when the pivot is under tension and the two links connected by that pivot are either bending or straightening. OK...? Do you have a picture that illustrates this or at least identifies the parts refered to? I have this http://user.it.uu.se/~embe8573/bike/...erminology.jpg but "pivot" isn't mentioned... By pivot, I meant the pin and the plates attached to it. The part that acts as a hinge. The point is, to get wear in the chain, you need pressure on the surfaces in contact, and you need relative motion between those surfaces. And how long should you be able to go before the slack exposes you a fraud mechanic and/or the owner of crooked gear? For derailleur bikes, many people recommend replacing a chain when it's worn (or "stretched") so it's one half percent longer than when new. (This is most easily measured with a ruler marked in inches. Do you have one of those?) Eheh... what's next, you going to ask Picasso if he has a brush? Of course I have folding rule, ruler, measuring tape, and calipers in inches as well as cm. Well, I didn't know. In the U.S. it's not unheard of for people to have no ruler that measures in centimeters. But you have to remove the chain to do this, right? Not usually. It's most easily done with the chain on the bike. Just use the cranks to apply a little tension. So it is not so fast after all. Even less so with a chain guard which is very common on these bikes. If the chainguard totally encloses the chain, then yes, it's more trouble. OTOH, if you have a totally enclosed chain, it will probably last as long as the bike. - Frank Krygowski |
#26
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new chain, slack
On Friday, December 22, 2017 at 7:01:07 PM UTC-5, Emanuel Berg wrote:
Frank Krygowski wrote: This has a couple possible implications. Here's one: sprockets (especially chainrings on less expensive bikes) are seldom perfectly round. Usually you can notice the change in tension (i.e. change in visible slack) as you turn the cranks with the bike on a stand. I suppose it's possible that the first estimate of chain "tightness" happened with the chain on a high spot, the next one on a low spot. That's true! What spot should you choose, then? I always put the crank vertically, the one where I can pull the most. I set the cranks in the position where the chain is tightest, and make sure there's at least a tiny amount of slack there. I haven't thought of the possibility of overstretching at the other end. But you have to pull really tight for that to happen, right? You won't literally stretch the chain no matter what you do. I suppose you might cause extra wear, though, if you had it excessively tight. - Frank Krygowski |
#27
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new chain, slack
On 12/22/2017 11:01 PM, Frank Krygowski wrote:
On Friday, December 22, 2017 at 7:01:07 PM UTC-5, Emanuel Berg wrote: Frank Krygowski wrote: This has a couple possible implications. Here's one: sprockets (especially chainrings on less expensive bikes) are seldom perfectly round. Usually you can notice the change in tension (i.e. change in visible slack) as you turn the cranks with the bike on a stand. I suppose it's possible that the first estimate of chain "tightness" happened with the chain on a high spot, the next one on a low spot. That's true! What spot should you choose, then? I always put the crank vertically, the one where I can pull the most. I set the cranks in the position where the chain is tightest, and make sure there's at least a tiny amount of slack there. I haven't thought of the possibility of overstretching at the other end. But you have to pull really tight for that to happen, right? You won't literally stretch the chain no matter what you do. I suppose you might cause extra wear, though, if you had it excessively tight. - Frank Krygowski Overly tight chain will destroy hub and crank bearings before significant chain wear. -- Andrew Muzi www.yellowjersey.org/ Open every day since 1 April, 1971 |
#28
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new chain, slack
On Saturday, December 23, 2017 at 8:59:06 AM UTC-5, AMuzi wrote:
On 12/22/2017 11:01 PM, Frank Krygowski wrote: On Friday, December 22, 2017 at 7:01:07 PM UTC-5, Emanuel Berg wrote: Frank Krygowski wrote: This has a couple possible implications. Here's one: sprockets (especially chainrings on less expensive bikes) are seldom perfectly round. Usually you can notice the change in tension (i.e. change in visible slack) as you turn the cranks with the bike on a stand. I suppose it's possible that the first estimate of chain "tightness" happened with the chain on a high spot, the next one on a low spot. That's true! What spot should you choose, then? I always put the crank vertically, the one where I can pull the most. I set the cranks in the position where the chain is tightest, and make sure there's at least a tiny amount of slack there. I haven't thought of the possibility of overstretching at the other end. But you have to pull really tight for that to happen, right? You won't literally stretch the chain no matter what you do. I suppose you might cause extra wear, though, if you had it excessively tight. - Frank Krygowski Overly tight chain will destroy hub and crank bearings before significant chain wear. -- Andrew Muzi www.yellowjersey.org/ Open every day since 1 April, 1971 I seem to recall manuals for 3-speed or coaster brake bicycles stating that cthere should be 1/8th of an inch slack in the chain at its tightest point. That was from the 1970s or thereabouts. Does that still hold true? CHeers |
#29
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new chain, slack
On 12/23/2017 9:00 AM, Sir Ridesalot wrote:
On Saturday, December 23, 2017 at 8:59:06 AM UTC-5, AMuzi wrote: On 12/22/2017 11:01 PM, Frank Krygowski wrote: On Friday, December 22, 2017 at 7:01:07 PM UTC-5, Emanuel Berg wrote: Frank Krygowski wrote: This has a couple possible implications. Here's one: sprockets (especially chainrings on less expensive bikes) are seldom perfectly round. Usually you can notice the change in tension (i.e. change in visible slack) as you turn the cranks with the bike on a stand. I suppose it's possible that the first estimate of chain "tightness" happened with the chain on a high spot, the next one on a low spot. That's true! What spot should you choose, then? I always put the crank vertically, the one where I can pull the most. I set the cranks in the position where the chain is tightest, and make sure there's at least a tiny amount of slack there. I haven't thought of the possibility of overstretching at the other end. But you have to pull really tight for that to happen, right? You won't literally stretch the chain no matter what you do. I suppose you might cause extra wear, though, if you had it excessively tight. Overly tight chain will destroy hub and crank bearings before significant chain wear. I seem to recall manuals for 3-speed or coaster brake bicycles stating that cthere should be 1/8th of an inch slack in the chain at its tightest point. That was from the 1970s or thereabouts. Does that still hold true? At minimum: http://www.yellowjersey.org/chainchk.html -- Andrew Muzi www.yellowjersey.org/ Open every day since 1 April, 1971 |
#30
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new chain, slack
Frank Krygowski wrote:
By pivot, I meant the pin and the plates attached to it. The part that acts as a hinge. The point is, to get wear in the chain, you need pressure on the surfaces in contact, and you need relative motion between those surfaces. OK, but is there a reason why you bring this up in such detail? Because isn't this just what one would expect to happen from pulling something in a chain? Well, I didn't know. In the U.S. it's not unheard of for people to have no ruler that measures in centimeters. Altho the metric system is completely prevalent here in general, it seems almost all specific fields has some or many conventions using the old English system. Not just bikes: boxing gloves, downpipes, drums... -- underground experts united http://user.it.uu.se/~embe8573 |
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