Chain tension

ThunderGuts · World Chat Champion Joined: 13 Nov 2018 Karma :

So the spec for my bike (VFR800X) says 30-40mm of tension. However, I am mechanically minded . . . I don't like to see undue stress on anything. When I set the tension to 35mm (yes, I did find the tightest point on the chain for setting this) and then sat on the bike and reached down to feel the chain, it felt just a bit too taut. I then slackened off to 40mm and it was still fairly taut but with a small amount of up/down movement. To me, this now seems acceptable (just about though!). The manual says not to ride with 50mm or more of slack (makes sense as if the suspension unloads over a bump don't want the chain jumping off the sprocket).

My question; why would the manual advocate 35mm or even 30mm if it's making the chain tension when the suspension is compressed so blinkin' tight? The adjustment is made on the side stand but otherwise unloaded - I have double checked this as I know there's some variation between different bikes. To me, having the chain really taut when sat on it is just going to accelerate wear on the output shaft of the gearbox.

Anyone else found this or have a different view?
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to v or not to v · World Chat Champion Joined: 24 Nov 2020 Karma :

sorry i dont know the answer to your question but i do know that its a lot easier to find neutral on my bike with a taut chain.

jaffa90 · World Chat Champion Joined: 06 Apr 2016 Karma :

I`ve always checked for chain slack when loaded, the KLR650 had a 50mm slack when unloaded, as said before watch them chains wag about on them MOTO GP bikes in action. (bollocks to the handbooks).

MCN · Super Spammer Joined: 22 Jul 2015 Karma :

If the OEM says set slack between 30 and 40 mm (unloaded) then that is the setting.
There's no need to over think this.

I continuously got the same argument from operators when I set up a system with no load.
They would cry that it needed load for set up.
I had to inform them that the setting I adjusted was OEM and that is the setting for the operational designed limits for the equipment

Write to the OEM and find out what they suggest?
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Disclaimer: The comments above may be predicted text and not necessarily the opinion of MCN.

stinkwheel · Bovine Proctologist Joined: 12 Jul 2004 Karma :

Remember that spec will be for setting up a brand new chain which doesn't have tight and slack spots.

You're happy with 40mm. Mr Honda is happy with 40mm. Everyone is happy. Very Happy

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pepperami · Super Spammer Joined: 17 Jan 2010 Karma :

I have no idea if it has any bearing on the matter.
One variable on chain tension with the rider on board is the weight of the rider.
Heavier rider = suspension is pushed further down = more tension on chain.
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jaffa90 · World Chat Champion Joined: 06 Apr 2016 Karma :

Nobby the Bastard · Harley Gaydar Joined: 16 Aug 2013 Karma :

One would think that the tension prescribed by the manufacturer of the fucking bike who spent fucking millions developing it would take into account the maximum length that would be possible due to the geometry of the rear end.

Just an idea. Not saying that people who weren't involved in the development of said bike don't know more than the people who did but.... yes, actually I am.
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Nobby the Bastard · Harley Gaydar Joined: 16 Aug 2013 Karma :

Ffs it's like saying the manufacturer didn't take into account the swinger geometry when fitting the shaft in a shaft drive and so you should fit a shorter one if you are a fat bloater.
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trevor saxe-coburg-gotha:"Remember this simple rule - scooters are for men who like to feel the breeze on their huge, flapping cunt lips."
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MCN · Super Spammer Joined: 22 Jul 2015 Karma :

stinkwheel · Bovine Proctologist Joined: 12 Jul 2004 Karma :

Nobby the Bastard · Harley Gaydar Joined: 16 Aug 2013 Karma :

I would imagine that the assumed weight would put the swingarm at it's maximum possible length of the chain when loaded. Why have suspension that could go past this?
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trevor saxe-coburg-gotha:"Remember this simple rule - scooters are for men who like to feel the breeze on their huge, flapping cunt lips."
Triumph Sprint ST 1050

chickenstrip · Super Spammer Joined: 06 Dec 2013 Karma :

Islander · World Chat Champion Joined: 05 Aug 2012 Karma :

Adjust it the way the manufacturer tells you to and stick to the range they give you. If it's 30-40mm and 40mm works best for you then all is good.

Don't worry about checking the slack when it's loaded - unless that's how the manufacturer tells you how to do it.

In short, don't overthink it. adjust it and ride it. Thumbs Up

MCN · Super Spammer Joined: 22 Jul 2015 Karma :

If the chain is adjusted to spec then tight when you sit yer big fat arse on the bike then the chain adjustment has not been done properly.
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Disclaimer: The comments above may be predicted text and not necessarily the opinion of MCN.

redeem ouzzer · World Chat Champion Joined: 06 Oct 2015 Karma :

I've yet to see a handbook yet that tells you to measure the tension under load.

Set as per manual, job done.

If I set my 1100 to the recommended 25-35mm slack under load rather than as specified by the manual it would flap around and take chunks out of the rubber buffer and also possibly the swing arm.
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jaffa90 · World Chat Champion Joined: 06 Apr 2016 Karma :

OK, i`ll try again, you need chain slack when loaded, i don`t mean 25mm,30mm,40mm. I mean not tight. On any new bike i check for the above and then note the chain slack when unloaded which may be up to 50mm on trail type bikes or bikes with long swing arm travel.
https://www.bikechatforums.com/viewtopic.php?t=303698

Islander · World Chat Champion Joined: 05 Aug 2012 Karma :

doggone · World Chat Champion Joined: 20 May 2004 Karma :

The worst thing done by those guessing and/or inexperienced is overtightening.
So follow what it says in the manual and if you don't have one try to look one up.
If that still can't be done it wants to still have a little bit of movement when shocks are well compressed e.g. Lie over the seat and check it, this will often seem rather slack when no weight is on it.

Overtight chain will wear much faster or even let go completely, and risks damaging other parts of the drive like gearbox and bearings.

ThatDippyTwat · World Chat Champion Joined: 07 Aug 2016 Karma :

Viffers are really picky about chain tension, you can feel it if it's wrong. It's largely a given that anyone that finds it's chuggy until 4K has set the tension on the sidestand. Funnily enough it's silky smooth when you set it, on the centre stand, to recommended 15-25mm (about 1" tops) and isn't otherwise.
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