V11 Sport tire size? - 170 vs 180

[Gio]

+1 on the question of a 160 for your '01 ...

[LowRyter]

How would a smaller rear tire affect the high speed wobble on the red frame?  would it make it worse or improve it?

 

I know stiffening the rear and increasing air pressure at the rear (and decreasing it in the front) improves the wobble.

[docc]

How would a smaller rear tire affect the high speed wobble on the red frame?  would it make it worse or improve it?

 

I know stiffening the rear and increasing air pressure at the rear (and decreasing it in the front) improves the wobble.

With my RedFrame, I find that the rounder profile of the 160 is less likely to weave at high speed than the narrower contact patch of the more "pinched" 170. Same for tires built with a rounder profile. (The original equipment Pirelli Dragon Corsa on the early Sports were somewhat more "triangular" and contributed to the weave).

 

LowRyter, your Sport may have the earliest triple clamps that really contributed to the weave issue. What's the part number under the top triple clamp?

[LowRyter]

I have no idea what is the part number of the triple clamp.  I can't see it.  It what it is.

 

I just put on a brand new 170 tire.  I guess I'll just wait another year or so and experiment with a 160  By your theory, the more mileage on the tire, wearing down the center, the bike should be more stable?

 

In the meantime, the rear shock is set to stiff and I keep the rear tire aired up.  I might think about softening the front.   It's just much worse with the big HB jrs on there.  I really noticed it when I had the shop put on new front tire and they aired it really stiff (like 40lb) and the bike was weaving &  bouncing all over the road.  I usually keep the rear about 4-5 lb heavier (40 vs 36lb), I might up the difference (maybe 42 to 34).

[docc]

Unfortunately, it's the spring rates (especially the rear) that affect this the most. I run 40/35 psi rear/front, but changed my springs years ago and set the sags. That solved the weave entirely. The smaller 160 could allow your Sport to settle to the rear slighty more.

 

It's really all about the springs and sags.

 

That part number under the triple is hard to see, but the earliest triples were, reportedly 1/2 degree steeper and these V11 are going to be harder to stabilize. I remember your Sport having the early finned steel exhaust flanges which makes me wonder if it's in the early triple clamp range . . .

[LowRyter]

Docc,  did you re-spring the rear, front or both?  Of course I weight 210 (thanks for noticing that I've lost weight).  But I am sure it was sprung for a 160 lb rider.   How much spring did you add? 

 

I am thinking about one of the suspensions in a box a deal.  

[docc]

I re-sprung both ends. I'm about 185 pounds in full riding gear  . . .  (*these days* - "thanks for noticing " . . . )

 

I went a little stiff on the rear Öhlins spring since I always have the Teknos packed with tools and beer and a plug kit with air compressor and beer, and jumper cables and beer.

 

Your suspension company should question you on your weight, gear, luggage, and riding style before recommending the spring rate. Traxxion Dynamics nailed my fork springs first time (cheap and easy improvement) while Andy York pinned down my Öhlins at the time.

 

It was, truly, the final solution. You'll be thrilled with the change.

[LowRyter]

I wrote the hyperpro guy and asked him about the suspension in a box and explained by goals and concerns.  

[Jazzamoto]

Just my 2 cents, I've got a 170 on my 2004 Cafe Sport (5.5" rim) and it does turn in more quickly. Too quickly, in fact. After it's worn I'll go back to a 180.

[helicopterjim R.I.P.]

Just read this topic and I am surprised no one has taken into account tire bias!

 

I have tried a 160/60  and a 160/70 ....... I tried a 160/60 years ago and it wasn't all that spectacular and also made the speedometer error worse. Went to a 160/70 and found a much better tire! Turned quicker and speedometer error was less. Looked better too.