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new chain, slack



 
 
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  #1  
Old December 17th 17, 10:43 PM posted to rec.bicycles.tech
Emanuel Berg[_2_]
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Posts: 1,035
Default 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?

--
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  #2  
Old December 18th 17, 02:02 AM posted to rec.bicycles.tech
John B.[_3_]
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Posts: 5,697
Default 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  
Old December 18th 17, 03:24 AM posted to rec.bicycles.tech
Emanuel Berg[_2_]
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Posts: 1,035
Default 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  
Old December 18th 17, 03:43 AM posted to rec.bicycles.tech
Emanuel Berg[_2_]
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Posts: 1,035
Default 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  
Old December 18th 17, 06:18 AM posted to rec.bicycles.tech
John B.[_3_]
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Posts: 5,697
Default 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  
Old December 18th 17, 01:06 PM posted to rec.bicycles.tech
Emanuel Berg[_2_]
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Posts: 1,035
Default 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  
Old December 18th 17, 01:55 PM posted to rec.bicycles.tech
Emanuel Berg[_2_]
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Posts: 1,035
Default 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  
Old December 18th 17, 07:07 AM posted to rec.bicycles.tech
Tosspot[_3_]
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Posts: 1,563
Default 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  
Old December 20th 17, 02:21 AM posted to rec.bicycles.tech
James[_8_]
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Posts: 6,153
Default 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  
Old December 20th 17, 03:20 AM posted to rec.bicycles.tech
Frank Krygowski[_4_]
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Posts: 10,538
Default 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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