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#1
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new chain, slack
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? -- underground experts united http://user.it.uu.se/~embe8573 |
#2
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new chain, slack
On Sun, 17 Dec 2017 22:43:17 +0100, 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? That's sort of asking "how long is a piece of string" :-) Bike chain, how many speeds, runs inside a chain case, how fast, how much power transferred, new cogs or old, lubricated, how frequently, etc., etc. -- Cheers, John B. |
#3
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new chain, slack
John B. wrote:
That's sort of asking "how long is a piece of string" :-) Actually, that was to be my very next question Bike chain, how many speeds, runs inside a chain case, how fast, how much power transferred, new cogs or old, lubricated, how frequently, etc., etc. OK, then let's assume a single speed bike, either Torpedo or Shimano. It does have a chain guard. Speed doesn't exceed 25 km/h. The person cycling weights in at 80 kg. The chainwheel and sprocket are 10-15 years old. The chain is lubricated one a month. -- underground experts united http://user.it.uu.se/~embe8573 |
#4
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new chain, slack
Bike chain, how many speeds, runs inside
a chain case, how fast, how much power transferred, new cogs or old, lubricated, how frequently, etc., etc. OK, then let's assume a single speed bike, either Torpedo or Shimano. It does have a chain guard. Speed doesn't exceed 25 km/h. The person cycling weights in at 80 kg. The chainwheel and sprocket are 10-15 years old. The chain is lubricated one a month. Oh yeah, the chain is the Shimano CN-NX10 1S chain which is 1/2*1/8. (silence) "Good specifications, Manny. In that case, I don't know" -- underground experts united http://user.it.uu.se/~embe8573 |
#5
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new chain, slack
On Mon, 18 Dec 2017 03:24:03 +0100, Emanuel Berg
wrote: John B. wrote: That's sort of asking "how long is a piece of string" :-) Actually, that was to be my very next question Bike chain, how many speeds, runs inside a chain case, how fast, how much power transferred, new cogs or old, lubricated, how frequently, etc., etc. OK, then let's assume a single speed bike, either Torpedo or Shimano. It does have a chain guard. Speed doesn't exceed 25 km/h. The person cycling weights in at 80 kg. The chainwheel and sprocket are 10-15 years old. The chain is lubricated one a month. One of the "etc's" has to be "and how far do you ride in a normal year, Sir?" -- Cheers, John B. |
#6
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new chain, slack
John B. wrote:
One of the "etc's" has to be "and how far do you ride in a normal year, Sir?" Wait, isn't that a function of the answer to *my* question (how many bike hours does a chain last) and the speed data? Obviously the average speed of urban cycling isn't 25 km/h. It is rather 15 or 10 km/h. Let's say 15 km/h to make the experiment more "fit" So now the data is: - A single speed bike, either Torpedo or Shimano. - It does have a chain guard. - The chain is the Shimano CN-NX10 1S which is 1/2*1/8. - Speed doesn't exceed 25 km/h; average speed is 15 km/h. - The person cycling weights in at 80 kg. - The chainwheel and sprocket are 10-15 years old. - The chain is lubricated one a month. -- underground experts united http://user.it.uu.se/~embe8573 |
#7
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new chain, slack
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 -- underground experts united http://user.it.uu.se/~embe8573 |
#8
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new chain, slack
On 17/12/17 22:43, 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? Fully enclosed hub/ss setup seem to last forever. My old dérailleur setup was a chain a year/ about 2,000kms. The current setup, with hub/open chain guard looks to be 3x that so far. One more year to make. |
#9
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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 |
#10
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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 |
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