Topic: jumpy front end

[mono]

i googled and got some results for "wobbly front end" end, but my issue is not with alignment (i checked it with a laser level and it's straight).

when i hit about 30MPH, the front starts to bounce a bit as though the tire is off-balance, and becomes less of a problem at 50ish -- haven't gone on the highway yet because of the bouncing, though...  ha. 

i just had it pro-mounted and balanced.  i don't think it was balanced on a high-speed balancer, though.  he said the tire was true also, even though i have a small dent in the rim.

before getting the new tire/tyre, this was not an issue.

bad balance job?  other ideas?

thanks

[flybox1]

service your forks.  long way - remove. rebuild. refill. 
fast way -  drain, rinse with mineral spirits, until it comes out clean, and refill.
do one side at a time.

[KurtK]

I had a front tire that did this.  I replaced and the problem went away.

[mono]

I had a front tire that did this.  I replaced and the problem went away.

LOL.  thanks.

[mono]

service your forks.  long way - remove. rebuild. refill. 
fast way -  drain, rinse with mineral spirits, until it comes out clear, and refill.
do one side at a time.

yeah, i have new seals but my current ones aren't leaky and i seemed to have good resistance on the front end.   guess i'll have to give in and do this. 

[TwoTired]

Tires are supposed to be round, but not all are.  Jack up the front and spin the wheel.  Does the tread appear uniform as it spins?

Also. mounting tubeless tires on the tube type rim takes some skill and attention.
I'm not sure why you chose to use a bent rim, but there is a molded line on the tire near the rim bead, and that line should be equidistant all around the rim.

Do check the rim itself for run out, too.

[2wheels]

+1 on new oil in the forks.
It is easy to do and it is what caused my problem which is just about the exact same as you are feeling.

Measure how much comes out of each fork, they should be the same.

[Rigid]

Check your bead alignment line around the rim I've had shops not seat the tire properly on the rim causing bouncing at certain speeds

[jakecb420]

i wouldnt rule out a bad steering stem bearing.  when i replaced mine on my 750k3, it seemed to smooth it out quite a bit.  since then, my front wheel has been trued and balanced, and progressive fork springs/ new seals in the front. my bike is smooth as glass now. i recommend you replace all the crap the front end and enjoy how nice your bike will handle.

[camelman]

I'd put money on a bad mounting job.  Check the molded line as mentioned previously to make sure it lines up consistently around the rim.  I'd also deflate the tire and push it away from the rim to make sure the tube wasn't pinched anywhere.  I found out my front tire had a pinched tube after taking it to one of the "pros" where I live.  I was able to push the tube back inside the tire, refill and carry on.  My wobble definitely decreased after that and I've put about 6000 miles on the tires since.

Camelman

[phil71]

Steering head bearings?

[mono]

I'm not sure why you chose to use a bent rim, but there is a molded line on the tire near the rim bead, and that line should be equidistant all around the rim.

Do check the rim itself for run out, too.

the rim has a tiny ding in it.  the show owner said it was true and that it should not cause a problem.  he's been doing this for 20-some years, so i believed him.  it is a tubeless tire with a tube in it.  he also balanced the tire, but i'll check it for shape.   

EDIT: -- TT, if the tire is slightly "unround" is that something that will go away as the tire wears?  my brain tells me "probably not", but you guys have all the real-life experience. 

[mono]

Steering head bearings?

not trying to be contrary, but you guys keep talking about the bearings in the steering stem -- wouldn't that just affect the L-R motion of the bars?  just curious - i know regular logic doesn't always apply to motorcycles though 

definitely feels like a balance/suspension issue. 

last season my 36-year-old front wheel had no bounce to it, so for now i'm ruling out the rim.  for the same reasons i'm suspect to think it's the forks (were also working A-1 when parked), but i'll do that 1st since i already have the stuff for it.

possible suspects:
- not round tire
- fork oil levels
- bad balance job
- pinched inner tube
- bearings?

[ChuckG750f1]

Check your bead alignment line around the rim I've had shops not seat the tire properly on the rim causing bouncing at certain speeds

I would do this first as well as make sure the tire is not way over filled.  Sometimes people put a very high PSI in the tire to seat the bead and forget to lower it to a normal pressure when they're done.

[phil71]

mono, if you ride a 36 year old motorcycle, and you do not know the condition of the steering head bearings, it's definitely time to change them. Yes, they can create all kinds of unsafe conditions that aren't obvious , or intuitive .

[TwoTired]

Do check the rim itself for run out, too.

EDIT: -- TT, if the tire is slightly "unround" is that something that will go away as the tire wears?  my brain tells me "probably not", but you guys have all the real-life experience. 

It's funny trying to imagine how an un-round tire can be made round with wear.  Perhaps if you only let it contact the road at its high points...  But, then there will be the out of balance thing as you wear off just the high side of the tire.

 It's not that hard to spin the front tire with it raised off the ground and watch for height variation.

Reminds of the guy getting a flat near the insane asylum fence, drawing attention of the residents.  As the guy gets out to look at the flat and ponder, a voice from the other side says, "it's only flat on the bottom".

Cheers,

[mono]

Do check the rim itself for run out, too.

EDIT: -- TT, if the tire is slightly "unround" is that something that will go away as the tire wears?  my brain tells me "probably not", but you guys have all the real-life experience. 

It's funny trying to imagine how an un-round tire can be made round with wear.  Perhaps if you only let it contact the road at its high points...  But, then there will be the out of balance thing as you wear off just the high side of the tire.

 It's not that hard to spin the front tire with it raised off the ground and watch for height variation.

Reminds of the guy getting a flat near the insane asylum fence, drawing attention of the residents.  As the guy gets out to look at the flat and ponder, a voice from the other side says, "it's only flat on the bottom".

Cheers,

OK OK OK... I'm laughing my butt off and hiding my face in shame at the same time.   haha thanks for clarifying. 

[mono]

mono, if you ride a 36 year old motorcycle, and you do not know the condition of the steering head bearings, it's definitely time to change them. Yes, they can create all kinds of unsafe conditions that aren't obvious , or intuitive .

they looked to be in good condition when i repacked them about 2 months ago.  the races were not notched, and the bearings looked like new.  when i reseated them they allowed for smooth travel, no crunchy sounds or looseness.   

[CycleRanger]

Tire rotation direction correct? i.e. tire isn't mounted backwards.

[mono]

Tire rotation direction correct? i.e. tire isn't mounted backwards.

yeah it's correct.  the little front/rear directional arrows say so.   

[phil71]

OH, so you do know the condition of the bearings. Great! Doublecheck the pre load on them, just to be safe.

[Brantley]

I had this exact problem two years ago (and I wouldn't have if I, or rather my shoulders, didn't hate mounting new tires). Are you seeing anything that looks like liquid being flung from your rim onto the sidewall of the tire? Kinda like if the rim was the letter "O" in a horror movie title? Happened to me; could not figure it out. Deflated and over way inflated several times to get the bead proper. Water started bubbling out around the stem. Try that. I think your installer may have used too much soapy water/ install lube. Leaving Fix-A-Flat in your car tires too long exhibits the same symptoms.

[mono]

I had this exact problem two years ago (and I wouldn't have if I, or rather my shoulders, didn't hate mounting new tires). Are you seeing anything that looks like liquid being flung from your rim onto the sidewall of the tire? Kinda like if the rim was the letter "O" in a horror movie title? Happened to me; could not figure it out. Deflated and over way inflated several times to get the bead proper. Water started bubbling out around the stem. Try that. I think your installer may have used too much soapy water/ install lube. Leaving Fix-A-Flat in your car tires too long exhibits the same symptoms.

now that you mention it, i think i did.  i'll check the tire again when i get home to be sure, but i wiped them down the other day and recall noticing that.