Topic: Tire Hop- Bent Rim or Something else?

[motorcycleclaude75]

Hi All,

My bike hops or vibrates especially at 30-40 MPH, higher speeds not as noticeable.  I know it could be many things, but are some tests that I could perform to diagnose this problem. You can feel the front go up and down quite noticably but is it the front that's causing the problem?

I know my rear tire had unusual wear, one section was more used than the rest of tire.

Should I just bring in both rims and get them checked out or is something I can do myself.  I had 2 new tires fitted and balanced so I want to avoid taking off the tires if I can.

Thanks for your input.

Claude

[dusterdude]

claude,mine does the same thing.now i attribute that to the fact i need to replace the fork seals in my front end and i also need a new tire.i hope this helps you out.

[Einyodeler]

If you just had tires put on and it started afterwards then most likely the tire isn`t seated right on the rim.

[bike54]

If you just had tires put on and it started afterwards then most likely the tire isn`t seated right on the rim.

or  balanced  properly

merv

[bob204bc]

I've had the same problem. It's probably a poorly seated bead causing a slight out of round condition. You can easily see this by proping the bike on its stand and spinning the tire. An out of balance tire usually doesn't bounce much at only 30-40 mph unless it has been forced out of balance.

I'd make the low spot. Take the wheel off, deflate it, work the pinched bead a bit with a rubber mallet and reinflate. That usually corrects the condition. I have heard some have recommended over inflating to "pop" the bead on the rim but I think that's a really unsafe idea.

[Uncle Ernie]

Occasionally, a tire is just "out of round" and needs to be replaced.  Many new dealers/shops don't know how to set the bead on an old-style tire. Could be balancing, but when that's happened to me it was because the tire wasn't seated.

[DammitDan]

Shot in the dark here, but have you trued the wheel and made sure all the spokes are tight?

I'm not sure if this would do what you're talking about, but it's still something to look at.

[Bodi]

I've had some trouble with tubeless tires on tube rims. It's supposed to be OK but the maximum speed allowable will not be as high as the tire rating because with a tube the tire runs hotter inside from friction. Really good tube-type tires are more or less unobtainable, there are Korean and Chinese tires that are at least as good as the best from the 70's era made to fit tube rims.
The problem is the tube type rim is very tight to the tire bead, a tubeless rim has a slightly different edge profile. You must use tire lube (soapy water is fine) on the bead and rim, inflate the tire to the sidewall maximum rating and deflate to your running pressure. Most tires have bead lines cast in the sidewalls, the lines should be equidistant from the rim edge all the way around.
Low speed pogoing is usually due to the bead improperly seated or a bad tire, or from water inside the tube. Water will collect in air compressor tanks and lines (unavoidable in fact, you need a proper air dryer to eliminate water in compressed air) and a surprising amount of liquid can be delivered  if you're unlucky and some trapped in the lines decides to pass out while you're inflating your tire. It tends to equalize at high speeds but through some voodoo resonance or something it can cause amazing wheel hopping at the speeds you describe.

[motorcycleclaude75]

Thanks for your input.

My brother suspects it may the the tire bead not set properly since the modern tires have a different bead.

My tires are tubeless type but I still have the tubes in each tire.

I'm gonna try deflating each tire and reinflating, and see if any improvements.

Claude

[Dennis]

Thanks for your input.

My brother suspects it may the the tire bead not set properly since the modern tires have a different bead.

.............
I'm gonna try deflating each tire and reinflating, and see if any improvements.

Claude

Before you go through all that trouble, why not just visually inspect the tires observing the bead line as BODI has suggested above?
That way "suspects" has nothing to do with it and you will know for sure if the bead is seated or not. Your way you are just playing with it and hoping the condition gets better.

[Badboy]

I have my bike up and on the road again,and it suddenly started this same hop. the tire is ,will not center on the rim[it is a contintental tubeless] no breaks that you can see,no weather cracks,etc. At first it did not do this as I can remember,it started al of a sudden. I could see the tire running out,tried deflating soaping ,reinflating still the line around the tire is not even. Is it posible to have a broken tire body and nothing you can see? A Yamaha dealer tried to seat it ,and they told me they couldn't seat it right either. they said the rim was okay. Are tubeless tires really compatable with these older rims anyhow?

[78_SaltLick]

my back tire has a wobble to it, took it to a shop and theres nothing that can be done other than replace the whole back rim, there are two broken spokes on it. Be sure to keep the spokes in mind when diagnosing a wobble.

[DammitDan]

I always thought spoked tires had to have an innertube?

[Gordon]

I always thought spoked tires had to have an innertube?

They usually do.  When they're talking about using a "tubeless" tire, they just mean the design of the tire.  You put a tube in regardless of what type of tire you are using. 

[78_SaltLick]

sorry to dredge this one up again, i am curious....my friend while riding behind me said he noticed a wobble on my back tire, i took it into a shop to have it trued but they told me the problem was a couple of broken spokes on the back wheel. Is this dangerous to ride around on a motorcycle with broken spokes? Is it cheaper to have the broken spokes replaced or just buy another back rim? Im wondering how he knows they are broken, there are two that are really loose, but not physically broken by what i can see. Is it as simple as tightening up the spokes like you would on a bicycle?

[Badboy]

It would seem to me that one or two loose or broken spokes would not in itself be dangeous ,if the tire is ok,and it does not run out to bad. But if there is something wrong with the tire that is something else. If it were me I would take a good look at it. If the spokes are just loose and not striped tighten them up,but be carefull you don't get it running out even worse. That is my two cents!

[swamprat]

Anything that spins has a critical point when the frequency of virbration in highest.  No matter how well balanced, true, or whatever.  I agree with all the posts on this topic...but spinning wheels will have a critical point that you can't do anything about.  Just my two cents worth. 

[Uncle Ernie]

First of all, you can go very fast all day with a tube in there. Yes it creates more heat, but not THAT much more. Having under-inflated tires will create more dangerous heat. 
Yes, broken spokes are dangerous.
If someone here is using tubeless tires on a spoked rim with no tube, I hope you carry a charged cell phone and cab fare.
Possible front-end problems; how long has the bike sat in one place and how old are the tires- you could quite possibly have flat spots from sitting.  When was the last time your antique forks were seriously flushed and the proper grade/amount of fork oil put in?  Check all around to make sure the bead is even. If it's not, put soapy water around the edges and blow the tire up to 90 lbs, or so. Let it sit a while and see if the bead pops out. That's about what I know to look for on verticle bouncing.