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Discussion Starter · #1 · (Edited)
I remember reading a thread somewhere about leading edge/trailing edge cupping and how it relates to your suspension settings. I can't find that thread so I'm someone can ELI5 what is going on here.

I'm on the stock OEM rear shock setup one click from full stiff. (I'm ~195lbs geared up). I understand how to set sag with the preload, but I have no clue how to dial in the rebound setting. I have it set roughly at 75% in the 'fastest' direction. How do I set it up?

Aside from that question, below you see a picture of my rear tire. You can see the rear wheel hugger on the right side so the direction of travel is left to right. I believe the side of the tread that is badly cupped is the leading edge because it hits the ground first. Is that correct? Why is the leading edge so cupped and the trailing edge is untouched?

Front:34psi
Rear:40psi

 

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Leading edge wear is sometimes caused by the rebound setting not being set correctly. You need to slow down the rebound. Do this by increasing the amount of rebound (turn the rebound adjustment screw clockwise). The additional or increase of rebound setting keeps the shock from rebounding quite as quickly and instead of the leading edge of the tire groove hitting first (on a rebound stroke), more of the area between the grooves makes contact instead of the leading edge. It's just the opposite if the trailing edge of the tire groove was worn lower than the leading edge.

On a side note, I'd lower tire pressure unless you are only commuting or carrying almost full rated capacity of the bike.....somewhere around 387 pounds.
 
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Discussion Starter · #3 ·
so am I correct, that is the leading edge that is cupping?
 

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I've used good old trial and error. Take your preload as an orientation for the rebound. If you are almost maxxed out on preload, you might want to try out 90% rebound and see how it feels. I have my preload on max and set the rebound to 1/4 turn from max. I'm heavier than you though (250 @ 6ft4). Bike feels great and very stable in bumpy curves, where it used to almost throw me off before I made the adjustments. Did you work on the front fork as well?
 

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Discussion Starter · #6 ·
I've used good old trial and error. Take your preload as an orientation for the rebound. If you are almost maxxed out on preload, you might want to try out 90% rebound and see how it feels. I have my preload on max and set the rebound to 1/4 turn from max. I'm heavier than you though (250 @ 6ft4). Bike feels great and very stable in bumpy curves, where it used to almost throw me off before I made the adjustments. Did you work on the front fork as well?
Thanks for the tip. I'll set up for sag and go from there. No I have not touched the front yet however now that I have my service manual, I'm going to stiffen that up all the way when I make my rear adjustments.


Leading edge wear is sometimes caused by the rebound setting not being set correctly. You need to slow down the rebound. Do this by increasing the amount of rebound (turn the rebound adjustment screw clockwise). The additional or increase of rebound setting keeps the shock from rebounding quite as quickly and instead of the leading edge of the tire groove hitting first (on a rebound stroke), more of the area between the grooves makes contact instead of the leading edge. It's just the opposite if the trailing edge of the tire groove was worn lower than the leading edge.

On a side note, I'd lower tire pressure unless you are only commuting or carrying almost full rated capacity of the bike.....somewhere around 387 pounds.

Thanks. That is helpful. I will try going a bit stiffer and see how that helps. Regarding tire pressure, I know this is a debate topic covered in another thread, but if I'm only riding solo and around 195lbs geared up, How low should I go? 30/34?
 
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