Tire pressure affects vibration?

[Dennis in NH]

Hm... so I'm aware our bikes vibrate -- a lot.

In fact, I remember removing my GPS because it vibrated so much on the highway, the USB power connection continued to work it's way out of the hole and I would have to keep pressing it back in.

I even mounted a Formotion thermometer onto the handle bars and it vibrated so bad, the liquid moved and vibrated out (making for an interesting display on the face of the thermometer) -- I didn't even know they were liquid filled until I got it on my bike and on the highway. The thermometer has since moved to the fairing and attached by a fairing bolt (much better now).

Anyway, to my point, ...
Last night, I checked my tire air pressures (getting colder in NH) and found I was low by about 7lbs. I put air in the tires and rode last night. First of all, I think the bike was really happy because I think the front wheel almost came off the ground on hard acceleration onto the highway. Does air really make that big of a difference? holy smokes -- I shall check more often.

But one really interesting thing is on my commute this morning, the handlebar vibrations were significantly reduced. I rode at 8K and 10K RPM and still the vibrations were quite tame. My GPS power cable stayed put and the GPS didn't feel like it vibrated that much. I thought I read one of the things to help vibration was tire pressure but didn't think it mattered. So it really does? how?

Thanks,

Dennis
ps.
Last night, I also removed my grip puppies -- somehow, I think they take away from the "feel" of the bike? with vibrations reduced maybe they are not as useful anymore.

Now that the S. NH temps are above 50F, I hope many folks folks took their bikes out :rockon:

 

[chihuahuastud]

How much PSI are you running?

 

[Dennis in NH]

I think I'm close to 36/40 front/rear; that was last night in about 60F. This morning was about 50F.

I "think" above because I have 2 different pressure gauges but one is 3psi lower than the other. The psi numbers above are from the gauge I trust (as I've been using it in my cars for several years); the other one is new and easier to use but not sure I trust it.

Dennis

 

[RJ2112]

Dennis, your FZ seems like it vibrates a lot more than mine..... The only time my mirrors get blurry, is when I'm romping on the throttle, and the tach goes past about 6K. and then we're talking about a little bit fuzzy, still useable image in the mirror.... up to about 9K. By that point, I'm not spending a whole bunch of time checking mirror image quality.

I've been running 33/36 for the past 4 years in at least 4 different tire sets, without any change in vibration..... are you sure it's road vibration? Does this happen when the bikeis on the centerstand as well? (sounds simplistic, but I've found it's important to make sure we're solving the right problem.....)

 

[Dennis in NH]

In town, I keep it below 6K RPM (maybe less) so no vibration to even notice there (I'm sure there is some but not enough to care). On the highway, if I'm relaxing, 6K RPM (about 74 indicated MPH) -- minimal vibration. I noticed vibrations late Summer when I took a long trip on the highway and I was cranking it at 8K RPM and above. This was when I noticed the unhappy thermometer and unhappy GPS.

I haven't checked tire pressure for a while -- since the bike "felt good" I didn't bother. Last night, I felt it was cold so I'd better check pressures and found they were low. I added air and now the vibrations seem very small.

Who knows. Nothing on the bike changed except air. Either way, the bike felt pretty good with minimal vibration this morning. But I just wish I knew what did it so I can keep doing it. The bike feels more comfortable this way and I can actually use my GPS on the highway without worrying about it running out of battery.

Dennis

 

[Motogiro]

I had BT-020's that came with the bike and was getting vibration and noticed the front tire had cupping, It almost seemed to follow the tread design as apposed to being a mechanical problem. Is your front tire cupping? Is it a BT021?

 

[RJ2112]

8K on the freeway in top gear works out to around 80 MPH, right? What's the vibration like, when you rev it to 8K in neutral? (trying to sort out if it's road speed related, or engine vibes) Obviously, if you run it at that RPM for extended periods, it can't hurt to do so in neutral for comparison.... except for if it PO's the neighbors.....

 

[Dennis in NH]

I'm running RoadSmart tires.

And at this point, most of the annoying vibration is gone. I'm sensitive to this stuff so I'll keep an eye out for any changes. The vibration is most noticeable in the handlebars -- hm..., I just thought of something that changed -- my gloves are my winter gloves (as opposed to my thinner Spring/Summer gloves). Maybe that's the difference.

When I'm in a lonely place, I'll give the 8K RPM a try in neutral. With Scorpions, I think it will annoy my neighbors .

Dennis