Tire hopping troubles!

[TW_rider]

Recently replaced the front tire on my TW. Everything seemed OK for the past week or so, but when I went out the other day, I noticed a bit of a "bounce" to the front end that wasn't there previously.
I had stuck a patch on a weak-spot in the tube, so I thought maybe this was the cause. Also hadn't lined up the BALANCING MARK with the valve stem.
Bought a new tube today, took out the old one, aligned the BALANCING MARK and went out for a test drive...no change!

Then I got to thinking...maybe it has to do with the valve stem. There are TWO nuts on the stem, so I left one on the inside and one on the outside...should I have only used one?
This "bounce" occurs at about 50kmh till about 70kmh...at which point it either vanishes completely, or is so fast I can no longer detect it.
Tire is brand new...tube is brand new...tube is NOT pinched or twisted...tire is fully seated...

Feels like I'm riding down the railroad tracks...this isn't "normal"...what is going on?

 

[c337b]

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Tire is out of balance. Take wheel off and stick a rod thru were the axle goes and prop it between to items ( chairs will work ) Spin it real real slow and it it is out of balance. Mark were it stops each time If it keeps going to the same spot its out of balance.

 

[TW_rider]

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...and then what?

 

[dirtrider]

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put the bike on a stand, pry the brake pads so they dont touch, spin the wheel and see where it stops. Mark the spot at 12:00...spin it again and if it keeps stoping at the same place get some stick on wheel weights and add weight to the opposite side until the wheel never stops in the same place...



Hint....tape the weights on until you find the correct amount and the place to put the weight...usually the weight is needed opposite the rim lock or valve stem...



in a pinch you can use solder....and wrap it around the spokes...

 

[TW_rider]

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OK...sounds easy enough to do.
What about the "two" nuts on the valve stem? Do I need one on the inside? Can I leave it the way it is? Where can I get some honest-to-goodness spoke weights?

 

[bigmac]

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Fishing weights work good. Hit up a sporting goods store. They come in a bunch of sizes.:hb:

 

[old trials guy]

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TW_rider wrote:

What about the "two" nuts on the valve stem? Do I need one on the inside? Can I leave it the way it is? Where can I get some honest-to-goodness spoke weights?

You only need the inside nut if you intend on tightening the outside stem nut to the rim. Personally, I never use the outside nut other than to jam up against the valve cap for storage as it comes in handy when changing tires or fixing flats.

I leave it off the eliminate the possibility of the stem getting ripped out of the tube. Even though I use rim locks I have seen the tire rotate slightly on the rim. A tight valve stem nut could have resulted in a torn stem and a flat.

IMO spoke weights are not as reliable as tape weights. I buy tape weights at Lordco or any auto store and I mount two set of them at 120 degrees to the rim lock or heavy spot as that improves balance.

otg

 

[Summit Seeker]

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I know this may sound stupid but I have found some paved roads to have washboard and other defects which could lead to tire hopping

 

[TW_rider]

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Summit Seeker wrote:

I know this may sound stupid but I have found some paved roads to have washboard and other defects which could lead to tire hopping

This is what I thought at first, since I had taken a road that I don't normally take for my test drives...
When I repeated the test on one of my usual runs, the result was the same...

Thanks to all for the tips and suggestions....I'll let you know how I made out whenever I can get back to it. :cross:

 

[Sparkle]

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Not all tire hopping iscausedby balance problems. Have a close look at the bead where the rubber meets the rim and make sure it is seated evenly all around on both sides. Sometimes a new tire has trouble seatingfully especially if the beadlock is hung up on the tire bead. If it's not seated, loosen the beadlock fully, and use a mallet or rubber hammer to true it up. Let some air out if necessary. There is usually a thin lip or rubber line on the tire sidewall that should be exactly even with the rim all the way around, both sides.

Also, it's not unheard of for anew tireto NOT be round. Spin the wheel using a stick or pencil to gaugethe runout.

I'd look for the bead to not be seated first.

Sparkle