Chain adjustment - why is it loose so soon afterwards?

[Morph 257]

I've adjusted the tension on my NC750X DCT chain twice now, in two weeks, and just returned from a 300 mile trip... to find its loose again.  What am I doing wrong here??

 

I put the bike on its center stand, find the place where its most loose by rotating the rear wheel.  Loosen the two axle nuts slightly (1/4-1/2 turn.  Then adjust the swing arm lock nuts, making sure they are both in the same tick position, then tighten up the lock nuts.  I use a ruler to ensure its about 35mm chain drop.

 

I then tighten the axel nuts back to where they were (I left some tippex on the nut and arm to make sure).  The nut hasn't moved.  The swing arm nuts are still locked, but the dang chain is whacking against the swing arm again!

 

Its only done about 12K miles from new.  Has OEM chain.  I'm not an aggressive rider - the sprockets don't seem to have any damage or hooking that I can see.

 

Do I just accept the chain is somehow weakened and swap it out?

 

Mike

Edited July 3, 2022 by Morph

[ted 5,759]

I've always tightened my chains, with it on its wheels and someone of similar weight as me sat on it.

[Skidt 1,332]

I stand to be corrected, but I was under the impression that you checked and adjusted the chain for tightness at the chains tight spot, rather than the loosest spot? 
My personal view is that the OEM chain is of dubious quality and perhaps part of the cost cutting measures employed to deliver the NC at its budget price point.
Mine, like yours, is only at just over 12k now. Ive also adjusted the chain several times over a short period. This is despite having a Scottoiler fitted, plus regular cleaning and additional regular lubrication. I guess if the bike (chain) had a poor maintenance regime in the 8k miles before I bought it, that could have caused irreparable damage.

I’ll soon be investing in a quality replacement. Hoping for a far better wear rate when that happens. 

[Morph 257]

Thanks for the replies. What's puzzling me is it is definitely tight enough when I finish doing the maintenance and then weirdly loosens up within a short period. So I believe a new chain is called for. 

 

I think it's also recommended to replace sprockets at the same time... But I'll ask my mechanic friend to have a good look when he does it.

[Skidt 1,332]

Absolutely. Personally I’d always replace both at the same time.

[Slowboy 20,648]

On my NC700x the OEM chain only lasted 12K, even with a chain oiler.  The DID replacement lasted well over 20k. The tell tale sign was a series of quick adjustments.

[shiggsy 529]

11k ws all i got out of the OEM chain. More than double after going to DID VX

[Xactly 5,499]

You should really use a torque wrench to tighten the axle nut. How do you know it was properly tightened in the first place? As others have said, you adjust the chain at its tight spot. The OEM chain may well have more than one. Are the rear wheel bearings ok, they are one of the few weak areas on these bikes if water has got in eg by pressure washing the bike?

[Morph 257]

when I last took it for a service I made those two tippex marks on the axle so I've just put it back to where the mechanic did.  he definitely used a torque wrench because I heard the telltale click when he was adjusting the wheel.

 

I don't think I'm mechanically qualified to tell whether the bearings are ok. But I'm really careful about using a jet washer anywhere near the chain/bearings ... I typically just use it on the bodywork and underside of the bike to get rid of the crud, and certainly nowhere near full power.

 

If anyone's got a good recommendation of an appropriate torque wrench set I'd be happy to hear it.

[ted 5,759]

2 hours ago, Morph said:

he definitely used a torque wrench because I heard the telltale click when he was adjusting the wheel.

 

They do that with their tongue when you're not looking.

[MatBin 5,115]

Just replaced my chain and sprockets (DID etc from Wemoto, with a split link 😱) at 12k, the OEM was shot, could have been lack of oiling etc by previous owner, but tbh I think the OEM is just a piece of old knicker elastic. Sprockets were ok(ish) but whilst it's apart I thought I would do it all.

Curiously my new chain varies in terms of up/down movement dimension depending on wheel rotation. I measure the total deflection i.e I pull chain up as far as it will go and then push it down to get the 35mm recommended at the tightest point, not the loosest, otherwise it will be too tight at the tight spot if you measure at its loosest.

[RC166 701]

Mine also has done about 12k miles and ready for replacement. A few stiffish links and tight spots. Original is a DID o ring, VO stamped on links. I’m replacing with the much better DID VX3 chain x ring and JT sprockets. 

[Steveg 1,049]

Still had original chain on my 2019 when I sold it at 22000 miles , surprised how long it lasted as was a poor quality chain , used gear oil in loobman 

 

Needed replacing soon when I sold it 

 

Recon would get 30k + on a decent quality chain 

[trisaki 2,029]

Tight spot on chain not loose spot - halfords torque wrench- they were on offer  

[listener 11,293]

20 hours ago, ted said:

 

They do that with their tongue when you're not looking.

 

You've been watching Rainman Ray's Repairs, haven't you?! 

 

 

[ted 5,759]

South Main Auto is my favourite.