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Chain Rub on SM set up

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Whats up fellas, ran into a slight issue with the Supermoto set up on my 2019 ktm 500. I have a 17x5” rear wheel, 160/60/r17 conti-attack sm tires, and a cush drive. I switched the front sprocket from 14t to 15t and noticed i had chain rub with my oem D.I.D o-ring chain. I picked up a new non o-ring chain thinking it would fix the chain rub issue. Unfortunately, I still have a slight rub. So when adjusting the rear axle blocks, i off-set the alignment about 1/8 inch to the brake side. Not noticeable by looking at the rear tire or chain, but by looking at the adjustments markers you can see it’s off a bit. That relieved the chain rub, but I’m curious to see what the negative effects of this can be.....if there is any. Like i said, not a whole lot, just a little bit, 1/8inch to 1/4inch at the most. Any thoughts or other ideas to fix the rub issue? Thanks guys.

DB8A3952-4801-4798-B31B-A5F52531E3A4.jpeg

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The misalignment at best will destroy your chain and sprockets in short order.  Worse it will cause you to throw a chain.  The rear rim needs to be offset more to the brake side for better clearance.  If there is not room to move the rim over you may need to run a different tire.  Some 160 street tires are very wide.  For example I can run 165/170 slicks on my YZ450 no problem but a 160 Q3 will not fit and rubs the swingarm.

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If it’s pretty minimal, I never worry about it. However I did get a 4.25” rim and 150 tire setup to avoid it. It can wear your chain a bit but in my experience the tire performance is not adversely affected.
There are chain blocks you can add to your swing arm to keep the chain in line. But it requires drilling into your swing arm. Toxic Moto Racing sells them.
Offsetting your wheel or picking a different tire can also solve the issue.

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All of the above.

If you want to keep what you have your best bet is to offset the rim by adjusting the spokes. You’ll probably still get a little rub as the chain will move side to side some as you ride. I wouldn’t worry about some occasional contact, just keep an eye on the tire and chain for excessive wear.

Definitely get the rear axle alignment back in though. You don’t want to have one side different from the other like you do now. 

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I switched from a DID ERV3 chain to the VT2 Narrow chain and that helped a lot.

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Its probably chain whip, unless you see it rubbing while sitting in the garage.

And what it takes to fix, are Guides, to keep the chain from whipping over and hitting the tire.

 

What I use is a TMD upper slide with side Bar guide and the Oem Chain guard

Now if its touching or close to touching in the garage , then you have other issues.

YOUR CHAIN Looks tight, not productive for good life

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54 minutes ago, Spud786 said:

Its probably chain whip, unless you see it rubbing while sitting in the garage.

And what it takes to fix, are Guides, to keep the chain from whipping over and hitting the tire.

 

What I use is a TMD upper slide with side Bar guide and the Oem Chain guard

Now if its touching or close to touching in the garage , then you have other issues.

YOUR CHAIN Looks tight, not productive for good life

Chain is definitely tight in that picture, still making adjustments to see what i can do about the rub. Figured I’d ask on here before i ride it and make the final adjustment. I actually measured from axle nut to peg on each side of the bike, which was exactly the same both sides, and looking down the chain, looks dead straight, i think the marks on the aftermarket axle blocks aren’t reliable.

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28 minutes ago, AntmanAce said:

Chain is definitely tight in that picture, still making adjustments to see what i can do about the rub. Figured I’d ask on here before i ride it and make the final adjustment. I actually measured from axle nut to peg on each side of the bike, which was exactly the same both sides, and looking down the chain, looks dead straight, i think the marks on the aftermarket axle blocks aren’t reliable.

Heres what I do as final test for perfect chain alignment ,   sit down behind the bike (wheel) level off the ground, and spin the wheel, look for a gap on both sides of the chain and the sprocket, it takes several times of doing this for insurance .

If the chain tends to have no gap on one side, then adjuster is too far out on that side. The adjuster marks are close , but not always perfect.  But having these gaps are what gives perfect chain alignment.

 

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11 hours ago, Spud786 said:

Heres what I do as final test for perfect chain alignment ,   sit down behind the bike (wheel) level off the ground, and spin the wheel, look for a gap on both sides of the chain and the sprocket, it takes several times of doing this for insurance .

If the chain tends to have no gap on one side, then adjuster is too far out on that side. The adjuster marks are close , but not always perfect.  But having these gaps are what gives perfect chain alignment.

 

When you say gaps, are you talking about gaps between chain and chain guide as the wheel spins? 

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2 hours ago, AntmanAce said:

When you say gaps, are you talking about gaps between chain and chain guide as the wheel spins? 

Im talking about gaps on both sides of the sprocket teeth.   There's close to 2mm play to work with, to equal out, so chain is not always touching one side of the sprocket. 

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15 hours ago, Spud786 said:

Heres what I do as final test for perfect chain alignment ,   sit down behind the bike (wheel) level off the ground, and spin the wheel, look for a gap on both sides of the chain and the sprocket, it takes several times of doing this for insurance .

If the chain tends to have no gap on one side, then adjuster is too far out on that side. The adjuster marks are close , but not always perfect.  But having these gaps are what gives perfect chain alignment.

 

I read this on another thread and tried it when i went to a 13T. Just made sense. I was not really surprised at how inaccurate the marks are on the stock blocks. I was very surprised at how sensitive the adjustments are on the stock blocks. I thought my bike was a smooth roller around the shop before the front sprocket swap. Now my 4yo niece could roll the bike around. It took some time but an Amazing difference for sure. Maybe it is me but i noticed less chain slap too boot. This is how i will do my adjustments on any bike i have. Thanks for the tip Spud786

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Thanks CMBThumper, don't think it will fix the OP's clearance issues ,as it will take more than that, but atleast can verify prefect chain alignment.

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there is a factory chain guide that goes on the top of the swingarm on the SMR models. The chain has to be taken apart to fit thru the solid piece on this one.

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This is what I use along with oem Chain guard, it takes something like this to keep chain side whip at bay , when doing high speed work.

You need both , cause they both take on wear , Both together greatly reduce all the wear on one, and being $79, you want it to be a life time item. I have like 45,000 miles on mine, but do have to replace the oem guard about every 20 or 25,000 miles

https://www.tmdesignworks.com/p-499-baja-endurance-front-chain-slider-pn-ktm-br1.aspx

I trim the oem guard slighty to fit(cause TND slider is longer than oem and I ty wrap the front part of oem guard to the swingarm  

but you need something similar, there may be other aftermarket stuff to use, but I keep it simple ,  Otherwise high speed work, I was routinely chunking off entire (chain side) knobs from chain whipping over and hitting the tire.

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