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Tansoo

Back tire rubbing on chain

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Had my fe 450 husqvarna converted to supermotard and the chain rubs on the back tire.  The set up is correct and lined up properly.

Can i drive like this or need swap to smaller size tire ?

thx   

 

 

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You want tore up contact with the road where you need it most? Smaller size me thinks. :excuseme:

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Ride it til the tire wears out, if you notice any performance difference, you can always try a narrower tire.

I've seen this plenty on supermoto bikes, mine included its nothing to worry much about.

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If everything is in alignment the only thing you can do is go smaller on the tire. Well it's not the ONLY other thing you can do but I'm not going there 😉

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I had the same problem with my KTM 500 EXC-F with both supermoto and ice tire set up. I found this upper swing arm guide from ToxicMotoRacing.com

Problem solved.image.png.63b78af8b0235693a2c44b0cbd7ebad4.png

image.png

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Posted (edited)

How is a chain guide going to help?  You would have to push the chain sideways, which would put a bend in the chain to be away from the tire.

Make sure your spokes are tight and the wheel is true then I would check your alignment with the front wheel.  Read a 'how to' or watch a video on how to do this with string.  You will need a helper, and if the tire is too chewed up by the chain the string method won't work.

I would not ride long term or even a weekend with the chain rubbing.  Being a tight ass myself, I would try sanding the tire where it is rubbing till it didn't rub.  You might only need to take 1mm of rubber off to stop rubbing, and your rear tire is still in line with the front.  When you think you've taken enough rubber off paint the tire where you've sanded and go for a 5 mile ride.  If the paint strip is intact you are good to go.  

The vast majority of riders never get to the edge of their tires when cornering.  

Buy a narrower tire next time.

Edited by OFS

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OFS, you are correct if you try to force the chain to run anything but perfectly straight sprocket to sprocket. That force would quickly wear out the guide and be really hard on the chain. In my case, the chain was not touching the tire statically. It was only hitting from the slight side play of the chain. The more the chain is worn, the worse that gets. That is why an upper swing arm chain guide such as the one I installed from ToxicMotoRacing.com worked for me. My supermoto tire looked just like the one in Tansoo's photo before I installed the upper swing arm guide. Adding the guide completely cured my issue. No more SM tire contact. No more ice tire screws destroyed. I couldn't tell from his photos if the chain was in contact all the time, or just from side whip like in my case.

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Sprocket alignment must be as close to perfect as possible. Using a high strength 520 chain and sprockets only helps if it gains space outboard from the sprocket mating surfaces. Don't use plain ole washers for this. They would need equal thickness, snug I.D. fit, and slightly larger O.D. than whatever they are in between. The outboard surfaces should be no further out than your current sprockets. Next option is to consider if retrueing the rims to one side a little will still let your brake discs work within the play limits of the calipers. If you are OCD, it will help. 

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Thanks for all the advise.  Will try to True the wheel and see if that solves it.  Will post the result.

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I used to see this a lot on custom H-D bikes back in the day. Guys would do chain conversions to run a fat rear tire and end up with the chain rubbing on the edge of the tire much like you have or much worse. 

Some guys would listen to reason and run a narrower profile but a few wanted to keep the tire they were currently running. Two common solutions that were done where I was at was grinding down the tire edge to clear the chain, or in the case of a laced wheel, changing the rim offset slightly by messing with the spokes. The second option changed wheel alignment and would have drastic effects on handling but since these were chromed out road slugs that didn’t handle worth a shit to begin with, the guys didn’t seem to notice. 

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