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Offline cnrcpla

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Chain tension
« on: April 23, 2013, 10:28:32 PM »
What's the best tension for a chain? I was doing 3 fingers between chain and swing arm on my old chain, but since I got a new, different one, it's fallen off twice now and more recently has caused me to wreck. I'd like to be able to trust it again, but I don't want to over tighten it... Two fingers maybe?  :-
« Last Edit: December 31, 1969, 04:00:00 PM by ' »

Offline asr524

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Chain tension
« Reply #1 on: April 23, 2013, 10:31:07 PM »
try calling the service department at a dealer that sells the brand that you have. they should be able to give you an actual spec distance for your bike.
« Last Edit: December 31, 1969, 04:00:00 PM by ' »

Offline _X_

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Chain tension
« Reply #2 on: April 24, 2013, 12:30:02 AM »
i do the old three finger trick, from the back of the slider. where are you checking it at?
« Last Edit: December 31, 1969, 04:00:00 PM by ' »

Offline cnrcpla

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Chain tension
« Reply #3 on: April 24, 2013, 01:31:12 AM »
At the back of the slider as well. It was holding up fine up until my last woods ride, it slipped off, jammed up in the swing arm, and locked my rear tire. Wiped out and had a fantastic time getting the thing off. My sprockets are literally brand new too. I don't think chain brand should have anything to do with tension, but I'll try and see what I can find about the specific brand. It's a D.I.D X ring.
« Last Edit: December 31, 1969, 04:00:00 PM by ' »

Offline msambuco

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Chain tension
« Reply #4 on: April 24, 2013, 02:34:35 AM »
Maybe covering something's you already know but here we go. First the wheel must be aligned directly with the counter sprocket by on a crate with the bike in gear put reverse tension on the chain. Eyesight from the rear sprocket looking up to the counter should have the chain looking like a straight line. Once this is correct when adjusting tension turn each adjuster bolt counting 1/6 turns and turning the other side by the same number of 1/6 turns to maintain the original alignment. As for the actual slack the best way to figure for any bike is to remove the shock and lift the rear wheel to the point where the most slack is needed to avoid over tension. Adjust to "not tight ,not loose". Install the shock back on and now find a 2 or 3 finger spot to gauge things by as a baseline and use this going forward. repeat for each bike you own as the are all close but slightly different (modern bikes). Occasionally check the alignment from the rear to the countershaft (and after any crash) and you should be good. I have never thrown a chain since my 78 RM100 so I think my methods (which is just chains 101) works.
« Last Edit: December 31, 1969, 04:00:00 PM by ' »
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Offline cnrcpla

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Chain tension
« Reply #5 on: April 24, 2013, 02:46:41 AM »
I'll double check the alignment, I've wiped out a few times since. I'll also do that shock trick. Thanks guys  :)
« Last Edit: December 31, 1969, 04:00:00 PM by ' »

Offline evo550

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Chain tension
« Reply #6 on: April 24, 2013, 03:27:01 AM »
Where is it derailing ?
from front or rear sprocket?
Tension or alignment will usually cause a front sprocket derailment, chain guide problems usually cause rear sprocket derailments.
« Last Edit: December 31, 1969, 04:00:00 PM by ' »

Offline cnrcpla

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Chain tension
« Reply #7 on: April 24, 2013, 03:30:30 AM »
Its been derailing from the rear. Maybe the chain guide is bent?  :-
« Last Edit: December 31, 1969, 04:00:00 PM by ' »

Offline evo550

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Chain tension
« Reply #8 on: April 24, 2013, 05:35:55 AM »
Good place to start looking, as most derailments occur when chain enters the sprocket, and the system runs counterclockwise (at least in the southern hemisphere) a front derailment would happen on the top of front sprocket and bottom of rear (chain guide area).
Also check chain and sprocket have the same pitch..
« Last Edit: December 31, 1969, 04:00:00 PM by ' »

Offline asr524

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Chain tension
« Reply #9 on: April 24, 2013, 02:04:45 PM »
At the back of the slider as well. It was holding up fine up until my last woods ride, it slipped off, jammed up in the swing arm, and locked my rear tire. Wiped out and had a fantastic time getting the thing off. My sprockets are literally brand new too. I don't think chain brand should have anything to do with tension, but I'll try and see what I can find about the specific brand. It's a D.I.D X ring.

I meant brand of bike. If you call the dealer and tell the service department what model bike you have they can look in the service manual for you. All service manuals have a chain slack measurement that can be checked with a ruler.
« Last Edit: December 31, 1969, 04:00:00 PM by ' »

Offline SachsGS

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Chain tension
« Reply #10 on: April 24, 2013, 02:38:01 PM »
As your rear suspension travels thru. it's arc the tightest point will be when the countershaft sprocket,swingarm pivot and rear axle are all in a straight line. You want to adjust your chain tension for this position. Are your swingarm pivot bearings getting loose? 
« Last Edit: December 31, 1969, 04:00:00 PM by ' »

Offline eprovenzano

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Chain tension
« Reply #11 on: April 24, 2013, 03:04:32 PM »
SachsGS I agree, most incorrectly check chain tension while the bike is on the stand...  The correct way is to remove the rear shock, cycle the tire up to find the point where the chain is the tightest.  Set the chain / wheel adjusters correctly and then re-install the shock. 

That's what I've always done, but I've then taken it one step farther.  Once its set correctly I'll make a measuring block. I'll put the bike on the stand, letting the tire droop on the stand.  I'll take a block of wood and use it to create a tool that I can use to quickly check the chain slack.   
« Last Edit: December 31, 1969, 04:00:00 PM by ' »
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Offline Micahdogg

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Chain tension
« Reply #12 on: April 24, 2013, 04:33:10 PM »
Last time I had a derailment issue it ws due to the swingarm pivot bearings being smoked.  Just a little play in those bearings translates to a LOT of play at the back wheel.
« Last Edit: December 31, 1969, 04:00:00 PM by ' »
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Offline cnrcpla

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Chain tension
« Reply #13 on: April 24, 2013, 07:47:12 PM »
Nope the swing arm bearings all got replaces recently. Linkage, pivots, and even wheel bearings were all done along with new sprockets and the chain this winter. I'll be doing the shock trick and making a tool to measure the slack once I have it dialed in, thanks for the ideas guys ;D
« Last Edit: December 31, 1969, 04:00:00 PM by ' »

Offline cnrcpla

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Chain tension
« Reply #14 on: April 25, 2013, 02:22:15 AM »
Rear chain guide was bent  ><img src=" title="Angry" class="smiley"> Got it all straightened out now, so hopefully no more derailment. I feel stupid not to have noticed that  :-[  Also set it to the right tension with the swing arm in the correct place. Its about two fingers from the top of the chain guide on top.
« Last Edit: December 31, 1969, 04:00:00 PM by ' »