Help reading tire wear

[atwater]

Ok so got a question for the suspension gurus. I installed a nitron r3 this spring to finish up the suspension on the bike and after a few days of spirited riding trying to read my tires to see what’s going on. Looks like the trailing edge of the tread is jagged and chunking out, Ignore the outer edges of the tire that was from a track day on the stock shock. Stock pilot road 3’s 34psi cold front and back. Did my best to balance the rebound between the front/rear. Rear Sag is 10-15mm free, 35ish rider think one step heaver spring would be ideal but close enough. This a normal for these tires or am I missing something. 

[stickshift]

Doesn't look like much to be concerned about to me, but your rear pressure is on the low side for road riding.

 

Manual recommends 33f/36r psi (cold).

[gregjet]

First that's the leading edge ( it will be on the other side on the bottom) on acceleration. An abrasive surface will do it under hard acceleration load. But I agree ,it seems a little chuncky. Giving it heaps on a sharp microsurface when cold will do it.

What's the manufacture date on the tyre?

[c3tkeyo]

Watched this last night, pretty interesting 

 

[fzar]

On 7/26/2018 at 10:20 AM, c3tkeyo said:

Watched this last night, pretty interesting 

 

Heres mine. I know its minimal. The video addresses it @ 5:03 - 5:21 I just don’t understand too HARD- TOO SOFT rebound. I have a stock shock 2015 set at 5 clicks out from previous owner, factory is 3 I think, so +2 from factory. Any thoughts or insight would be helpful. 

[mossrider]

Just now, fzar said:

Heres mine. I know its minimal. The video addresses it @ 5:03 - 5:21 I just don’t understand too HARD- TOO SOFT rebound. I have a stock shock 2015 set at 5 clicks out from previous owner, factory is 3 I think, so +2 from factory. Any thoughts or insight would be helpful. 

I think you may be confusing 'rebound' which on  the stock 2015 shock is non adjustable with 'preload' which is the big ramped collar that ratchets up or down the amount of preset pessure on the coil spring.

 

'Too hard' or 'too much' rebound means the suspension can't return (extend) fast enough from repeated, rapid compressive movement, ie it falls behind in its ability to recover or rebound  so it packs up, loses travel with each succesive compression and hammers the bike.

 

Conversely 'too little' or 'too soft' rebound means the componant is returning too quickly to its original condition, ie is slapping back at the ground which tends to make the bike bounce or float.

 

Ideally you'd want a balance of controlled resistance to both compressive force (compression damping) and extensive force (rebound damping) for a smooth controlled ride. This keeps the tires in contact with the road surface the highest percentage of riding time to maximized traction.

 

Both conditions can cause loss of traction and handling problems that can be seen or 'read' in the tires. See video above or any of the many similar ones on the web. The stock shock is notorious for having too little rebound damping for most people or applications, regardless of where the preload collar is positioned. Under normal street riding conditions the effect is acceptable to most people. It is only under very hard street conditions (or track) that it is most noticeable, it usually takes the entire life of a street riden tire to see any ill effects manifested.

 

As you can see this is a black art that few, including me, really understand. 

 

Hope this helps.

[elmo]

At the end of my last track day asked Dave Moss his thoughts on my tire ware. While there is other variables, he keep it simple.  Front- high leading edge = less dampening (quicker) and Rear- low leading edge = add damping (slower).  Similar to video.

 

I also have 2015, for myself it was easy as I have Penske shock and Matris fork inserts with adjustable rebound. However if  stock shock and fork you  have neither. Oil wt. change in forks could help, not sure it anything can be done for the shock. Stock shock clicks are for spring per-load only,  no help with rebound.

 

[elmo]

FYI- Something worth noting from Dave’s comments. The shiny area of the sidewalls is not the location to make your assessment for rebound. Since this shiny area is usually at max lean and not under a heavy load. Rebound adjustments should be based on the remaining area of the tire that's usually under heavier braking or acceleration loads.