Fork service ?

Discussion in '7th Generation 2010-Present' started by glory racing, Jul 2, 2013.

  1. lshark

    lshark New Member

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    what is spec for the front sag ???
     
  2. glory racing

    glory racing New Member

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    This question can get as many different answers as which tire/oil should I run. For the forks you will hear anywhere from 10 - 30 free and 25 -50 rider sag. I am running 15 and 25. No top out problems last weekend.


    To start and really know what you are working with, I would see what your actual "range" of free/static sag you have available. Therefore, what the spring does just holding up the bike with full preload and zero preload. Then you can set the more important rider sag when you have some help. Some may say that static sag doesn't really matter, but this is what determines how well your spring is matched to your bike.

    Let us know if you have more questions and how it turns out.
     
  3. JamieDaugherty

    JamieDaugherty New Member

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    Guys, please do not bother with static/free sag! The only number you should ever measure or care about is total rider sag. Being too concerned about a bunch of numbers only gets you confused. In every case I have seen guys end up with the wrong spring rate because they were spinning in circles with static and rider sag numbers.

    Forget about static sag. Use a knowledgeable suspension person to help you determine the correct spring rate for your application. There is so much involved with generating the correct spring rate. A little bit of trust in someone and setting your rider sag is all you will ever need.
     
  4. lshark

    lshark New Member

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    yeah it feels good !!! but just went out to garade to maybe fiddle with it a little and i noticed that the rebound damping was set differently on each leg....made the adjustment and will take it to work later....but it felt more controlled and handle those infamous Jersey potholes much better
     
  5. glory racing

    glory racing New Member

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    I understand that rider sag trumps static...but why would you not want to know the figure and how well the spring supports the bike? Especially when the stock bike offerings (VFR 1200) are so undersprung. Its not really that confusing.
     
  6. glory racing

    glory racing New Member

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    Tried to quote lshark's last post...but I suck.

    Good job catching. Remember humans worked on your bike and they make mistakes. Some of them quite often. Another reason to check static sag...that human may have installed the wrong springs as well.
     
  7. lshark

    lshark New Member

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    i supplied the Ohlins springs that i purchased online
     
  8. JamieDaugherty

    JamieDaugherty New Member

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    Ok, this gets pretty complicated, but let me give you some things to think about on this topic:

    1) The bike always has a rider. Why would you care what it does when no rider is aboard?

    2) Using the so-called "suggested" static sag and rider sag values you can end up with just about any spring rate. Take a look at what you state in post #42 and you'll see what I mean.

    3) Rider sag is a value that leaves most of the travel to absorb a bump (compressing the suspension). The amount of travel in the rebound direction (i.e. the sag measurement) is used when the road "falls away" but mostly to control over travel when the suspension rebounds after hitting a bump. That leads us to the most important aspect...

    4) The actual calculation for the proper spring rate also includes the damping force, and is a very complicated equation. It looks at how much the suspension deflects when hitting a bump of a certain size. That's what is important: you only have a set amount of suspension travel but you want to use as much as you can. That's why different applications, be it street, track, etc., end up with different spring and damping rates - the speed of the impulse is different and therefore generates a different resulting suspension deflection. You'll notice that nowhere in this calculation does the motorcycle weight by itself ever come into play.


    I know this is a difficult topic to understand, but I hope this helps shed some light on it.
     
  9. lshark

    lshark New Member

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    so i've gotten some riding in and there is def an improvement...best way to describe it; on known bad sections of roads on the ride to work where i would prepare for it to get a little out of shape, the bike is much more controlled, the wheel seems to stay on the road instead of bouncing over the bumps
     
  10. glory racing

    glory racing New Member

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    Congrats! Glad you are experiencing some improvement. Did you happen to determine/remember your free sag and/or rider sag numbers? (guess I am one of those who does care what the bike does without a rider) :)
     
  11. azi

    azi New Member

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    Jamie do you have a rule of thumb for motorcycle rider sag? Coming from the mountain bike world, I have always used 25-33% of total travel as a starting point, maybe 20% in racing context. Nice thing about MTBs is you just pump in or remove some air.

    Another thing is that trying to find out suspension travel specs on motorcycles isn't always easy.
     
  12. lshark

    lshark New Member

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    preload adjuster at factory default setting, rebound 2 clicks shy of max...don't have the time or someone to help with the sag measurements i'm going old school, heading up to the mountains tomorrow with my 14mm wrench and flat screwdriver and fine tune it like we did our MX bikes
     
  13. glory racing

    glory racing New Member

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    Sounds like fun...enjoy!
     
  14. JamieDaugherty

    JamieDaugherty New Member

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    Yep, you got it. Motorcycle are very much the same, in fact I've always assumed mountain bikes get their values from what motorcycles have proven over the years.

    In the case of the VFR1200 I would shoot for 35mm of total rider sag. Anything in the range of 30-40mm is considered good.
     
  15. glory racing

    glory racing New Member

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    Remember, the VFR 1200 only has 106mm ,slightly over 4 inches, of total fork travel. If you ever ride the bike a bit on the sporty side you may want to consider a bit less sag.

    Again, I am running at 25mm rider sag with a 1.2kg spring and have not experienced any topping out issues. Just fyi...my stock springs used up 45mm of the travel just to hold itself up! That's no rider weight, just the bike. Pretty hard to get rider sag at 25 when you are starting at 45!
     
  16. JamieDaugherty

    JamieDaugherty New Member

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    Correction - the VFR1200 has 120mm of front suspension travel. The VFR800's have 109mm.
     
  17. glory racing

    glory racing New Member

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    Not according to the service manual...108 for the VFR 1200! Perhaps it is a misprint?
     
  18. Dangerous Dave

    Dangerous Dave New Member

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    I actually couldn't find fork travel in the service manual. But the press info stickied at the top of this forum says 4.7" travel, which translates to 119.38mm. Where did you find that spec of 108mm?
     
  19. azi

    azi New Member

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  20. JamieDaugherty

    JamieDaugherty New Member

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    My notes and all other sources I've found says 120mm, so I'm confident of that number.
     
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