Author Topic: Chain tension (/slack)  (Read 7127 times)

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Offline bonne

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Chain tension (/slack)
« on: April 08, 2021, 21:43:58 »
Hello - I have always had my bike serviced regularly, thus never minding to check the chain tension for correct tension.

Now I want to care for it myself, and I want to understand its limits.

Manual says correct tension is 20-30 mm slack measured at the middle of the chain when the bike is on the side stand.

My chain slack is now 40 mm, and from my eyes to tell, this is the same tension level as when I was used to get my bike back from service. When I Summarise google results about the subject, I get that a chain should better be on the loose side than on the tight side as a tight chain will cause more wear. I read that better 30-40 mm on the DL1000 than 20-30 mm indicating that the 20 mm in the manual is incorrectly too tight.

Should I leave the tension on 40 mm or tighten it to say 30 mm? Or 25 mm?

I can guess that if the chain gets too loose, it will wear more on the sliding rubber on the chain guard and in worst case, it will slide off the sprockets and naturally cause serious damage. At which tension are we talking here? 80 mm? Because some bikes like off road bikes are suggested a slack of 70 mm

My bike is often loaded with a lot of weight.


Offline Ianmc

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Re: Chain tension (/slack)
« Reply #1 on: April 08, 2021, 21:54:49 »
Leave it, chains run better and last longer when they are a touch on the slack side rather than a touch on the tight side.If you want to make sure get someone to sit on the bike and move it backwards and forwards whilst you check the tension in a few different spots.
Ian Mc.

Offline Joe Rocket

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Re: Chain tension (/slack)
« Reply #2 on: April 08, 2021, 22:08:40 »
What Ianmc says.  :thumb:

The chain has to be greatly stretched and mal-adjusted to get anywhere near it having enough slack to ride off the rear sprocket. It probably needs to be at least two links longer, if not four!  :shock:
So how's it going so far then?

Offline Mr Nick

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Re: Chain tension (/slack)
« Reply #3 on: April 08, 2021, 22:21:46 »
What you are looking for is the chain to have just a bit of slack when the rear axle is at its furthest point from the front sprocket. The manufacturer has worked that out for you, but you can do the same by compressing the rear end until there's a straight line through the centre of the 2 sprockets and the swingarm pivot. You can do that by getting someone to put their weight on it until they line up, or use a ratchet strap if you have no handy friends.
The more suspension travel you have, the more slack you have to build in as the distance varies more. The slack on my KTM is to be 35-40mm but the suspension travel is 210mm compared to only 160mm on yours. A new chain can cope with more slack than an old one as the new chain resists side deflection more and is less likely to ride up on the sprocket.
Seems pearl asbo orange is faster after all....

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Offline Sea-Strom

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Re: Chain tension (/slack)
« Reply #4 on: April 08, 2021, 22:51:47 »
I'm a bit of a guesstimate merchant! With the chain I push it up in the middle - if it just touches the frame when stretched, it's OK. With the tyres, I knock with my middle finger knuckle ... I think the correct sound is just south of  F#  :icon_wink:

Ps also if there is a Yaris in front, and you are following, your speed will be about 20 mph.  :)

More 'university of life' gems of mine available on request!  :old:

Offline Mr Nick

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Re: Chain tension (/slack)
« Reply #5 on: April 08, 2021, 23:17:08 »
And if it's a Honda Jazz, you'll be doing 40 regardless of the speed limit in force...
Seems pearl asbo orange is faster after all....

'Don't believe all the quotes in forum signatures' - Aristotle

'Ehh, good enough' - Mediocretes

Orange Bikes Matter!

Offline bonne

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Re: Chain tension (/slack)
« Reply #6 on: April 09, 2021, 04:49:08 »
Sea-strom... this was actually exactly the tip I was waiting for. Because my chain IS in fact just touching the frame when I lift it, and I remember me thinking that if this is a valid guesstimate, this would be so much easier then measuring with a ruler

I am not sure about the tyres and tuning them that way... Think pressure gauge is quite easy, but I know of bike mechanics using tuning forks to tension spokes to the correct tension. (;

Offline Sea-Strom

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Re: Chain tension (/slack)
« Reply #7 on: April 09, 2021, 06:47:08 »
I'm sure most mechanics know if a chain is OK without ever picking up a ruler! Actually the tyre knock merely reassures me that no deflation has occurred. I tend to adjust pressure more with the seasons. I must confess I worry more about chain lubrication than tension. In winter a lube per outing is required in bad weather whereas chain slack is often good for much longer. I tend to use the 90 degree at a time tighten method as long as long as the wheel seems central. I also find that the transmission performs  better when the chain is at the tighter end of  the range than slacker. Chains tend to loosen rather than tighten in time as a general rule. Each to our own though!

Offline Gert

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Re: Chain tension (/slack)
« Reply #8 on: April 09, 2021, 07:54:29 »
For your own safety, stick to the setting in the manual. The setting is published for a good reason.  https://www.v-strom.co.uk/smf/index.php?topic=39042.0

Offline bonne

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Re: Chain tension (/slack)
« Reply #9 on: April 09, 2021, 13:51:35 »
I am aware of that and that is what I am afraid of. But what is understand on others in here, the slack on a new chain should be quite larger than my 40 mm.

Or?

Offline Gert

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Re: Chain tension (/slack)
« Reply #10 on: April 09, 2021, 20:26:45 »
Lets attempt to sketch a pix of the swing arm vs chain tension, for those new to chain drives. The chain tension / slack is tested while on the side stand or a center stand. While on these stands, the swing arm is not under any current load, while on any of these stands. When the rider sits with full weight (with or without any extra weight due to luggage / passenger / etc) the swing arm is now under load. This means that the swing arm moves from a slight inverted V to roughly a straight line between the front sprocket shaft and the rear axle, thereby causing the chain to effectively tighten. The chain slack has to allow for the swing arm to move under loaded weight, as part of the rear suspension. Too tight chain will either snap or wear faster, so run your swingarm through it's full travel and adjust to the tight spot. Too much slack may cause unplanned dismounts / lock ups / etc.
See https://www.vstrom.info/vsri-gallery/gallery/d/85994-1/chainslack.jpg for 20 -30mm suggested chain slack.
 

Offline bonne

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Re: Chain tension (/slack)
« Reply #11 on: April 10, 2021, 03:52:11 »
Yes, I understand the geometry of the bike. And that tension will be more tight when the bike is under load. I don't get your point on that regarding having a chain that is to slacked compared to the manual?

Looking at the video you posted, it seems that the chain is extremely loose.

Correction to my previous post. Slack on a new chain CAN (not should) be quite larger ... Sorry for my English

Offline Gert

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Re: Chain tension (/slack)
« Reply #12 on: April 10, 2021, 07:40:25 »
I tried to explain the reason for chain slack vs no slack vs how the swing arm pivot change influences the chain tension. The amount of slack is to a degree a personal preference. Some riders have reported that a slightly tighter chain makes for a smoother clutch / gear operation. An example, when coming to a stop and unable to shift into first gear without double clutching or increasing the rpm slightly. One would think that the clutch is out of adjustment in such cases, but chain tension also plays a role.

Offline RoadWarrior1978

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Re: Chain tension (/slack)
« Reply #13 on: April 10, 2021, 09:10:25 »

A brand new chain will have an initial elongation, however this is much less noticeable with modern chains. That will occur within short period, I.E after a short ride and that should be checked and in the unlikely event adjusted if necessary.

As for the day to day, 20-30mm is the correct book measurement in both owners manual and FSM, That said, I have found that to be insufficient and as a result I tend to run a little more. It seems to me that the manufacturer relies upon the cush drive rubbers deflecting as the swingarm travels through its arc to allow for a tighter tolerance.

Offline Mr Nick

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Re: Chain tension (/slack)
« Reply #14 on: April 10, 2021, 10:47:28 »
The cush drive doesn't allow fore/aft movement as it's on a bearing on the same axle as the wheel: it's there for damping the rotational shocks. If yours moves forwards then the bearing is stuffed.

Running too tight and too slack both cause issues. the slacker it is then the shock loading of coming on & off the throttle is greater as the system can take a longer 'run' at it each time. Too tight applies constant load to the chain and shaft bearings. The numbers developed by the manufacturer are based on more than just looking about right, but it's your bike so do whatever you think sounds better.
Seems pearl asbo orange is faster after all....

'Don't believe all the quotes in forum signatures' - Aristotle

'Ehh, good enough' - Mediocretes

Orange Bikes Matter!

Offline Mep

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Re: Chain tension (/slack)
« Reply #15 on: April 10, 2021, 10:58:10 »
With the tyres, I knock with my middle finger knuckle ... I think the correct sound is just south of  F#  :icon_wink:

If it's Ab then you're in trouble  :grin:

Offline Brockett

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Re: Chain tension (/slack)
« Reply #16 on: April 10, 2021, 11:02:17 »
Chain Adjustment - Just do what the "book" says. Suzuki don't guess this stuff. If there was a better way or more options then Suzuki would tell you.
This doesn't last forever, so do it while you can.

Offline UK_Vstrom650

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Re: Chain tension (/slack)
« Reply #17 on: April 10, 2021, 14:18:01 »
I always find the gears start to crunch when the chain is too slack, and it's noticable smoother shifting when set back to spec of 30mm

Offline RoadWarrior1978

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Re: Chain tension (/slack)
« Reply #18 on: April 10, 2021, 20:56:42 »
The cush drive doesn't allow fore/aft movement

I didn't think that one through properly  :shrug: my bad, for some reason I got it in my head the sprocket carrier had a self centering bearing allowing the carrier to pivot around it, must've been having a brain fart.

Thank's for reminding me that a cush drive is for taking up the shock loading of coming on & off the throttle, I'd totally forgotten its proper function  :grin:





Offline doboy

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Re: Chain tension (/slack)
« Reply #19 on: April 11, 2021, 22:57:01 »
Talking of chain tension my mate had an xj6 yamaha and he is a faffer , cannot leave well alone ..he put a new chain on his bike just before setting off for France . Set the slack as per manual but adjusted it a little more thinking I'll not have to adjust it while away then just a bit more tension ...anyway he only managed Calais and the rubber 0 rings were coming out of the chain due to the heat so he losted three days of travel ( as all bike shops in France are closed on mondays ) and paid through the nose for another new chain ...I can tell you he has had a very slack chain since then 😀😀😀