New Distanzia - head shake

I replaced by rear stock tire with a 150/70 17 Distanzia yesterday , using the front stock tire until it wears out a bit more and it gets replaced by a Distanzia front. Around 65-70 on the Interstate I start picking up a slight head-shake. The bike has always been rock solid at speed before. Their are so many variables that could be causing this and I will be going into the shop tomorrow and try to locate the problem, but always want to cheat a little by getting some advice from some of the more knowledgeable riders here.

Stock Bridgestone on the front 29 psi
150/70 17 Distanszia rear. 29psi; good mount and balanced

I had lowered the forks 10 millimeters when I had lowered the rear, but raised them 5 millimeters because of the larger Avon Diameter.

I increased about a half turn the rear spring to put my sag at 3.5-3.75 inches ( Im 234 lbs) The rear is definitely higher and stiffer.

May be that front sock tire is just not going to work well with the Distanzia. but after a 50mile scrubbing ride I played in the twisties and the bike handled great.

Any wisdom is welcome.

Play with the air pressure a bit. Drop to 26 psi and see what happens.

I only ever experience mild twitchiness in bars at about 80mph and above.

I have posted where I can let go of the bars altogether at speeds approaching 60 mph with confidence.

Your using two very different tires with very different profiles.

You may need to drop psi lower than you think to get some kind of contact patch on the ground that finds a compromise between the two tires.


Before I'd futz with suspension and/or ride height I'd definitely play with psi in the tires.

Thanks Motokid. I want to take a tape to the bike and make sure that rear tire is on square, and then I'll drop pressure to 26 and take it for a ride. I was amazed at the differance in weight and thickness of the two tires. The stock tire is so thin, light and flexable compared to the Distanzia.The Avon is soooo nice!

You may also want to play with having a ratio between front and rear psi.

Front might need to be higher than rear - or visa-versa.

Since the front does more braking, and carries less weight (typically) I usually have the front one or two psi lower than the rear.

Not sure if that would solve any of your head-shake issues but again - you've mixed two radically different street tires.

Treating them the same regarding psi might not be the trick to happiness.

Just thinking out loud here.

Like you said the tires are radically different from each other. I'm off to the garage to see what I can do, but my gut feeling is that mixing these two tires will not work at high speed.

For the record, I don't know what the right answer is, but here's what I think:

If the rear end is "definitely higher and stiffer" you've got more weight on the front. Excessive weight on the front sounds bad (I've analysed my crash as much as possible, and I'm fairly certain I landed standing and leaning over the front causing the massive tank slapper).

And if you're getting some headshake at 65-70 you must be going in a nearly straight line, which would eliminate at least the mismatched tire profiles as the culprit.

I've gotten some advise from other members who run this tire an am going to play with the air pressure. Then I might raise my forks more then the 5mm I already have, which would put them back to stock( rear height lowered almost 2") If none of that works I going to go ahead now and get the Distanzia front instead of waiting.

Just to end this for anyone going this route is the future I fixed the head shake by running 30 psi in the Bridgestone and 35psi in the Distanzia.

mordicai wrote:

Just to end this for anyone going this route is the future I fixed the head shake by running 30 psi in the Bridgestone and 35psi in the Distanzia.

If you're happy and comfortable that's all that matters.


BUUTTTTT


35psi sounds really high. Really high.

You should check your psi after a short medium and long run to see what "hot" tire psi is.

I'd bet in California, over 90 degree days, you'll be up over 40 psi in no time.


Again - it's your call. No head shake is important.

I just feel way more "planted" and secure with psi under 30.

Motokid, Thanks for your input. You have helped me out many times . I think that psi is dependent on many issues and what works for one does not work for all. You are 155? lbs. I am 230lbs. You may ride more aggressively then me and need the extra traction that a lower psi affords. I do 100 miles a day, forty on the Interstate and need to get some milage out of these tires. Josh runs 39psi front and back and loves it. I finally opened it up on the twisties yesterday and had no slippage at all although were I am doing 50 you may be doing 70. As a final note I think the idea of using the original x tire on the front with the Distanzia on the back to save some money until the front wears out is bullshit. Tires are too important to screw around with. I'm going to order the 120/70R17 Distanzia and be done with it.

39 psi

Holy shit.


I had Cycle Gear mount my Distanzias on the wheels for me. They sent them home with me inflated to about 40 psi.

I did not think to check psi and bolted the wheels onto my X and took for my virgin ride on what I assumed would be heaven made out of rubber.


Well, needless to say I thought I'd made the biggest mistake of my motorcycling life. The "feel" I experienced was so awful I was almost ready to go postal.

Calmer heads prevail as the saying goes...... when I checked the tire pressure I was flabbergasted.

I immediately bled off 10 psi from both tires and brought them down to 30 psi. HUGE difference in feel.

Glad your happy.

It is really amazing how "personal" something like tire pressure can be.

Happy riding.

I know, I had the same reaction to 39 when he told me, but because of that ,I made the move to 35 which cured the headshake. The tires rated to 42, but I suspect that's for the big enduros.

I had a different compound in the 150/60/17 distanzia, but I ran 28 psi.

f3joel wrote:

I had a different compound in the 150/60/17 distanzia, but I ran 28 psi.

Yeah....I'm finding 24-26 front, 26-28 rear is real comfortable.