Saving a chunking knob...?

12 replies to this topic
  • malignity

Posted April 30, 2012 - 05:45 AM


I just put some new Kenda 760's on my XR650L, and went and did a 150 mile dual sport ride yesterday; 75 miles of which were some of the roughest trails I've ridden in my 23 years of dirt biking.

Long story short, the extremely rocky terrain caused a partial chunking of my central section in a row of knobs. It's about 65% still connected, but has what appears to be a fairly deep tear. The tire has less than 500 miles on it, and I really don't want to scrap it since the tread is still good. I was thinking if I got some sort of tire glue, I could possibly save the section and not have to immediately replace the tire.

Any suggestions as to what kind of glue to use to try and repair the knob?


Posted April 30, 2012 - 08:54 AM


yes. you can glue more rubber on the broken off knobs..

.. uh, no. :banghead: you can't. It's junk, ride it like it is or get another. One thing that many don't comprehend. Hard terrain tires are SOFT COMPOUND RUBBER. Soft terrain tires are HARD COMPOUND RUBBER. You need softer rubber knobs to bend and flex on hard terrain, downside is the sharp edges wear down faster than the hard compound soft terrain tires.. but the soft terrain tires will chunk if you get into some hard terrain or seriously rooty stuff. Pick your poison.

  • malignity

Posted April 30, 2012 - 10:15 AM


The knob is still intact. I'm not asking if I can glue knobs on.. I know that's not possible. Lol.

I'm saying that at the base of the knob there is a tear starting. I'd like to be able to fix the tear before the knob gets completely chunked off, because it appears the way the tear is going, it appears like it's going to tear off more knobs with it if not properly fixed.

For what it's worth, the other two riders with me rode the exact same terrain with the exact same tires (ironically we all ride Kenda 760 rears) and they had no chunking or splitting at the base of the knob done to theirs. I just happened to be unlucky.

Edited by malignity, April 30, 2012 - 10:16 AM.


Posted April 30, 2012 - 11:15 AM


no, if there is a tear, the next ride or two that knob will chunk off as the others that already did. See that every time my ms3 begins chunking. when new it is fine, but with after a fair # of rides you see one or 2 chunk, with tears on others. those soon follow. Ask what psi those guys used if it was the same tire. I also find just like in roadracing, you use more tires the faster you go.. A rekluse clutch could help with your tire chunking some, as you will have less tire spin in some sections if your not slipping the clutch perfect by hand.

  • malignity

Posted April 30, 2012 - 02:40 PM


Of course everything looks 10x worse in the moment than in actuality when its sitting in the garage. Lol. It's actually not nearly as bad as I anticipated. I put some patch glue on it, some simple rubber cement and we'll see if it holds. I almost considered using contact cement. If the knob chunks, I think ill be fine regardless. Though it does seem to wear somewhat quickly, especially on freeway usage, I am EXTREMELY happy with the Kenda k760 off road.

I made it 50 miles home on the freeway and it didn't chunk, so hopefully it stays with the life of the tire.

Edited by malignity, April 30, 2012 - 02:41 PM.

  • tribalbc

Posted April 30, 2012 - 07:07 PM


You might get a little more life out of them using Shoe Goo. I use it on all forms of plastic and rubber repairs on the bike and gear. Just a couple days ago the night before hitting the MX track I noticed a big gash to the cords on the sidewall of my front tire. Didn't feel like swapping tires in the cold so globed some Shoe Goo in there. Lasted 2hrs of engine time pounding out fast laps at the MX track.

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  • CBus660R

Posted May 01, 2012 - 07:05 AM


The glue will not really work (don't let your 50 mile freeway ride fool you). Either the glue won't be as strong as the rubber so the tear will break back open again (the glue will fail), or the glue will be even stronger than the rubber, and the tire will tear just above or below the original problem spot. Anyways, I think the real issue is you probably got an older tire that was sitting in a warehouse for a while and started to dry out. That's why your buddies with the same tire didn't have the same issue.

  • stlavsa

Posted May 01, 2012 - 10:01 AM


Gluing isnt like welding. IF the knob able to be torn when it was a single solid piece, think about how easily it will be torn with glue as a fastner.. wont work.

  • malignity

Posted May 03, 2012 - 04:53 PM


I tried rubber cement and it didn't even hold up for 3 miles. LOL

My dad is insisting that if I use contact cement, it'll hold. I'm not sure if I should go with shoe goo, contact cement, or maybe even 3M 5200 Polyurethane adhesive. I hear that 3M crap holds damn near anything in place. Worst case scenario, I just cut the row of knobs off. Would rather not though if I don't have to.

Edited by malignity, May 03, 2012 - 04:53 PM.

  • adam728

Posted May 04, 2012 - 03:15 AM


Just ride it. No glue or cpntact cement is going to hold on knobs that are half torn off. That being said, you might be surprised how much of a tear it takes before you'll lose a knob. I went thru a lot of tires living in Arizona, now in Michgan I can't hardly believe how long a knobbie will last (running a Kenda 760 rear, oddly enough).

You say your buddies had no issues. You either have an older tire, an heavier bike, a more powerful bike, or just twist the throttle harder!

  • orangehorse101

Posted May 04, 2012 - 08:22 AM


Get snow where your at? do this with your old tire and get a new one for the dirt!

Posted Image

Edited by orangehorse101, May 04, 2012 - 08:25 AM.

  • stlavsa

Posted May 04, 2012 - 10:49 AM


I tried rubber cement and it didn't even hold up for 3 miles. LOL

My dad is insisting that if I use contact cement, it'll hold. I'm not sure if I should go with shoe goo, contact cement, or maybe even 3M 5200 Polyurethane adhesive. I hear that 3M crap holds damn near anything in place. Worst case scenario, I just cut the row of knobs off. Would rather not though if I don't have to.

IF you have any of that shit laying around that what i would use. I definitely wouldnt go out and buy any because im completely certain that you will be wasting your time and money.

  • jqueen

Posted May 04, 2012 - 10:56 AM


if it's just a crack so far, have you thought about trimming the knob so that you cut just the cracked portion off? You'd end up with a smaller knob with no tear. Not sure why you would think about cutting the whole row of knobs off.

I don't think you'll find any kind of glue that will hold. It MIGHT slow down progression of the crack, just a tiny little bit. But it won't stop it.

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