#11
|
|||
|
|||
new chain, slack
avagadro wrote:
Riding over sand with factory lube wudnot produce slack for miles By the way you mean this figuratively? Because isn't 5 miles ~= 8 km? I think I ride that every day 365d/y $ units '5 miles' km * 8.04672 / 0.12427424 -- underground experts united http://user.it.uu.se/~embe8573 |
Ads |
#12
|
|||
|
|||
new chain, slack
On 12/18/2017 7:55 AM, Emanuel Berg wrote:
Another issue is - when does chain wear occur? Is it when pedalling forward or is it when starting and stopping, including the foot/coaster brake? Here we assume "normal" usage It's reasonable to assume that wear is proportional to the product of contact pressure and velocity. That would mean that stopping with a coaster brake would cause almost no wear on the chain. You need motion between the parts in contact to have wear. If you're starting from a stop by applying extra torque to the cranks (as is usual) you would get extra wear at that moment. But it's only for a moment. I suspect it has little overall effect. -- - Frank Krygowski |
#13
|
|||
|
|||
new chain, slack
Frank Krygowski wrote:
If you're starting from a stop by applying extra torque to the cranks (as is usual) you would get extra wear at that moment. But it's only for a moment. I suspect it has little overall effect. OK, so when and why does wear occur? And how long should you be able to go before the slack exposes you a fraud mechanic and/or the owner of crooked gear? -- underground experts united http://user.it.uu.se/~embe8573 |
#14
|
|||
|
|||
new chain, slack
Worn sprockets
Plato ? slowly I turned .... See utube on worn bicycle sproxkets or harris brown worn sprockets chain rings cassettes Chain chain ring replacement |
#15
|
|||
|
|||
new chain, slack
On 12/19/2017 12:05 AM, Emanuel Berg wrote:
Frank Krygowski wrote: If you're starting from a stop by applying extra torque to the cranks (as is usual) you would get extra wear at that moment. But it's only for a moment. I suspect it has little overall effect. OK, so when and why does wear occur? And how long should you be able to go before the slack exposes you a fraud mechanic and/or the owner of crooked gear? Take a couple of minutes to read Jobst Brandt's chain wear analysis in the purple text box he http://www.yellowjersey.org/3%2732.html -- Andrew Muzi www.yellowjersey.org/ Open every day since 1 April, 1971 |
#16
|
|||
|
|||
new chain, slack
On 12/19/2017 1:05 AM, Emanuel Berg wrote:
Frank Krygowski wrote: If you're starting from a stop by applying extra torque to the cranks (as is usual) you would get extra wear at that moment. But it's only for a moment. I suspect it has little overall effect. OK, so when and why does wear occur? 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. 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?) But for a bike with only one rear cog, I think can go much longer. I'd say if the chain on a single speed or hub gear bike doesn't skip when you pedal your hardest, it's probably OK. We'll see if others disagree. -- - Frank Krygowski |
#17
|
|||
|
|||
new chain, slack
Frank Krygowski wrote:
:On 12/19/2017 1:05 AM, Emanuel Berg wrote: : Frank Krygowski wrote: : : If you're starting from a stop by applying : extra torque to the cranks (as is usual) you : would get extra wear at that moment. But it's : only for a moment. I suspect it has little : overall effect. : : OK, so when and why does wear occur? :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. : 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 ne of those?) But for a bike with only one rear cog, I think can go :much longer. :I'd say if the chain on a single speed or hub gear bike doesn't skip :when you pedal your hardest, it's probably OK. We'll see if others disagree. The issue with going too much longer is that you wear the crank teeth and rear cog teeth. They cost more, and are harder to change, than a chain. Single speed and IGH bikes can use a wide chain, which will lost a long time (particularly if fitted with a good chain guard/case. -- sig 22 |
#18
|
|||
|
|||
new chain, slack
On 18/12/17 08:43, Emanuel Berg wrote:
It seems after putting on a new chain, it turns really slack after only 2-3 weeks. When you then restraighten it, it remains tight considerably longer. Is this so or does intuition play a trick on me? In general, how many bike hours does a chain last? 2-3 weeks seems like only a short amount of time under "normal" conditions. There are too many variables to quantify exactly "how long". 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? I'd expect at least 2000-6000km from a new chain to wear 1%, depending on the conditions and the rider. The Wippermann chain test shows more than a 3:1 wear rate from the best to worst chains they tested. (36 to 114 hours of their abusive test.) http://www.cantitoeroad.com/Wipperma...ained_b_2.html Standard bicycle chains measure 1/2 inch from pin centre to pin centre. There are something close to 100 half links or 50 inches of chain, so 1% is one half link or 1/2 inches of wear. That would mean the rear wheel would need to be moved 1/4 inches rearward to take up the slack from a worn out chain. (Actual number of links or half links depends on the length of chain stays and the crank and hub gear diameters.) -- JS |
#19
|
|||
|
|||
new chain, slack
On 12/19/2017 8:21 PM, James wrote:
On 18/12/17 08:43, Emanuel Berg wrote: It seems after putting on a new chain, it turns really slack after only 2-3 weeks. When you then restraighten it, it remains tight considerably longer. Is this so or does intuition play a trick on me? In general, how many bike hours does a chain last? 2-3 weeks seems like only a short amount of time under "normal" conditions.Â* There are too many variables to quantify exactly "how long". 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? I'd expect at least 2000-6000km from a new chain to wear 1%, depending on the conditions and the rider.Â* The Wippermann chain test shows more than a 3:1 wear rate from the best to worst chains they tested.Â* (36 to 114 hours of their abusive test.) http://www.cantitoeroad.com/Wipperma...ained_b_2.html Standard bicycle chains measure 1/2 inch from pin centre to pin centre. There are something close to 100 half links or 50 inches of chain, so 1% is one half link or 1/2 inches of wear.Â* That would mean the rear wheel would need to be moved 1/4 inches rearward to take up the slack from a worn out chain. (Actual number of links or half links depends on the length of chain stays and the crank and hub gear diameters.) Another factor: The geometry of the situation means it takes only a tiny change in length (or position of the axle relative to the cranks) to generate a noticeable amount of slack. 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. Conversely, if someone installed a chain and happened to have it at a low spot on the sprocket, then bolted the rear axle in place, the crank's high spot might over-tension the chain. It might even have enough leverage to pull the axle forward when a properly adjusted chain would never do so. Or the over-tensioned chain might wear more quickly, I suppose. (I learned about this problem in a related way back in my pre-BMW days, when my motorcycles had drive chains.) Finally, no matter what the situation, it seems the chain must have some microscopic roughness - peaks and valleys - on mating parts. The peaks would tend to wear off in the beginning generating at least some clearance. Once the peaks wore, further wear would be much slower. This is partly why engines are (or were) supposed to be carefully "run in" or "broken in" when new. -- - Frank Krygowski |
#20
|
|||
|
|||
new chain, slack
On Tuesday, December 19, 2017 at 4:07:53 PM UTC+1, Frank Krygowski wrote:
On 12/19/2017 1:05 AM, Emanuel Berg wrote: Frank Krygowski wrote: If you're starting from a stop by applying extra torque to the cranks (as is usual) you would get extra wear at that moment. But it's only for a moment. I suspect it has little overall effect. OK, so when and why does wear occur? 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. 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?) But for a bike with only one rear cog, I think can go much longer. I'd say if the chain on a single speed or hub gear bike doesn't skip when you pedal your hardest, it's probably OK. We'll see if others disagree. On a single speed you have the same wear criteria as with derailleur system if you want to replace the chain without replacing the cog or chainring. If you accept that you have to replace the cog and/or chainring when you replace the chain than you can go on until you can't tension the chain anymore or the teeth are completely gone. Lou |
Thread Tools | |
Display Modes | |
|
|
Similar Threads | ||||
Thread | Thread Starter | Forum | Replies | Last Post |
OBree uses a slack chain | someone | Techniques | 68 | September 16th 09 02:19 AM |
OBree uses a slack chain | Fred Fredburger[_6_] | Racing | 0 | September 15th 09 08:09 PM |
Advice On Slack In Kh-schlumpf? | Paulo | Unicycling | 4 | May 18th 08 07:57 PM |
Chain side slack | Pat and Bob Chambers | UK | 1 | September 8th 05 11:37 AM |
Chain Side Slack | Pat and Bob Chambers | Australia | 1 | September 8th 05 09:23 AM |