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Weight on the back improves handling?

Discussion in 'New Riders and Riding Tips' started by Sooty, Apr 8, 2009.

  1. Today I had to cart a cordless drill and batteries/charger in the rackbag, probably 5kg? I normally carry a 2ltr bottle of water and some other stuff too so say I had 7kg sitting on the back of the bike today. For reference I weigh 75kg.

    The difference it made to the stability and handling was positive. I loved it - bike felt planted, grip on tap, falling into corners was nice. When coming to a stop it no longer dropped the front - I always switch to rear only and ease off in the last meter or so and it would still drop.

    I was expecting worser handling.

    So if I had a better bike with adjustable suspension - would I expect similar differences given correct adjustment? Or maybe my existing shocks are dodgy?
  2. mate, if you put 150 kilos on the back and it starts singing, call it a day :grin:
  3. need a bigger rack. no wait...
  4. after reading some of the 'twist of the wrist II', the weight distribution when cornering should be 40-60, in favor of the rear, so by adding some weight i would think it would feel more 'grippy', not sure if there would be a limit as too how much before these numbers change?
  5. Is your rear preload setup correctly for you when you aren't carrying all that gear on the back?
  6. Non-adjustable :|
  7. I don't believe you.

    It's unlikey to have compression or rebound adjustments but I'm quite sure rear preload is adjustable on you bike (as it is on anything more advanced than a 1990 Repco moutain bike). Look more closely. :)
  8. Mountain bike 1, GPX250 0.

    Double checked the service manual - Rear Shock Absorber Adjustment: The spring preload can not be adjusted.

    Others have swapped it out for one off another make of bike. A new aftermarket shock will set me back $700AUD (Hagon, preload+damping adj)

    Although a shock from an '08 model is a drop in replacement and has preload adjustment. Might be lucky to find one off a wrecked bike?
  9. Oh welll.... just gaffa tape some bricks to the back then. :)
  10. The 40-60 weight balance talked about in TOW is about your breaking and throttle control (Fundamentally) if you need greater weight at the rear to be stable in corners you can apply a little more throttle (Or apply it a little earlier) to achieve similar goals. I found that when I could roll on earlier on the ZZR it stabilised the bike nicely through the turn.
    Now as for the preload thing… Are you absolutely certain the GPX doesn’t have it? The ZZR did and I thought the shocks were the same for the two bikes.
  11. I'll give it a closer look but I think it's one of the main gripes of the GPX250.
  12. +1 to F-L

    The manual for my ZZR also says that the preload is factory set and not adjustable, but when I was servicing the bike on the weekend I looked at the rear shock and it appeared to have a twistable-collar type thing that looked awfully like some kind of adjustment mechanism, so I figured it would be for rear preload.

    Is that what preload adjustment would look like, and so is there the possibility that the owners manual is wrong about it with the GPX/ZZR?

    F-L - what year was your ZZR that did have preload adjustment?
  13. I would be a little wary of the effect you are feeling...
    ...more weight on the rear could indeed have a positive effect on straight line stability...but it comes at a cost in ohter areas...

    I'd suggest that the weight being up high is allowing the bike to tip in more easily, because it has effectively destabilized the bike a little bit...(And may be that's what it needed - who knows)...but that destabilizing effect could also take you to the limits of the bikes geometry/suspension package in other ways, when pushed.

    Try it for a while...may be it WILL turn out to be something that you like and can adjust to - then keep it. :)...or not...depending on how it feels after a few weeks.

    Note...more weight on the rear, does not automatically equate to better handling...there is far more going on, and that need to be taken into account.

  14. The rego year was 99, though the 2000 model
  15. +1 to this.

    The static weight distribution of a motorcycle is around 50/50, which is fine - TOTW is talking about managing the bike's dynamic weight distribution using the throttle and brakes. :)
  16. I have a Kawa manual for an 87 GPX and in section 12 page 8 it clearly shows an adjustable (pre load) Unitrack shock. I can scan the page if you like. :wink:
  17. [​IMG]
    Excerpt from my manual

    Photo taken of top part of rear shock

    Doesn't appear adjustable - no notches or thread?
  18. Wasn't so much the tip in than how much more 'planted' it felt on the road. I could feel what tyres were doing on the road. Normally I receive very little feedback from the tyres and it's not exactly confidence building. I'm apprehensive about weighing down the rear - as you say who knows what its doing to the rest of the bike. I would rather achieve the same effect by adjusting the suspension instead of the blunt approach of adding dead weight.
  19. I always thought the GPXs were non-adjustable too. I stand to be corrected, but that was my assumption throughout 2 years of owning one, and mine was an 88 import.

    Later GPXs and the ZZR may have gained preload adjustment, or some older bikes may have had newer shocks put in when the originals crapped out.

    2wheelsagain I don't have my manuals anymore, but I never saw anything about adjusting suspension, and I had a couple of different versions covering EX/GPX/GPZ/Ninja250.

    Would have loved to be able to adjust it when I had it, both ends were a bit squishy and I'm only 75kgs!
  20. i just checked my service manual for the ZZR too - and the service manual clearly outlines the adjustment of the preload for the rear shock, even though the owners' manual says it is non adjustable.

    so looks like the owners' manual is clearly wrong in a lot of cases!