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Discussion Forks - RWU Vs USD

Discussion in 'Motorcycle Racing and Track Days' started by jmw76, Jan 11, 2023.

  1. jmw76

    jmw76 Well-Known Member

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    @Frankster I think the general idea of the USD forks was to reduce the unsprung weight and add a bit more stiffness.
    That said the cbr250rr and others have done very well with standard forks. For a drag bike, I can not see any real advantage. Running lighter RWU forks just might help you.
     
    jmw76, Jan 11, 2023
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  2. Murdo

    Murdo The Good Doctor Staff Member Contributing Member Ride and Events Crew

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    How can a heavy steel pipe reduce unsprung weight over an alloy tube? I have never weighed any but the alloy sliders always feel lighter to hold than steel legs.
    Fashion fads to sell more bikes?
     
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    Murdo, Jan 11, 2023
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  3. jmw76

    jmw76 Well-Known Member

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    jmw76, Jan 11, 2023
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  4. ruckusman

    ruckusman White Mans Magic Master Premium Member Dirty Wheel Club

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    I've wondered the same and I do actually have sets of conventional and USD forks apart at the moment, so I'll weigh some uppers and lowers.

    It won't be a truly apples:apples comparison as there's years between the manufacture, but 96 YZF600 RWU -v- 2006 ZX6R USD should be relatable. One thing is that earlier ZX6R RWU forks were 46mm upper stanchions for rigidity, whereas the USD are 41mm lower stanchion so it would seem that for 'equivalent' rigidity USD forks can be thinner
     
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    ruckusman, Jan 11, 2023
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  5. Murdo

    Murdo The Good Doctor Staff Member Contributing Member Ride and Events Crew

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    Murdo, Jan 12, 2023
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  6. Frankster

    Frankster Grey Pride...Adventure before Dementia Staff Member Premium Member Ride and Events Crew

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    If anyone has a ZZR250 bike or front end can you PM me or post the dimensions of everything (fork size, triple tree length, centre to centre etc) please. Thanks

    upload_2023-1-12_10-10-11.png
     
    Last edited: Jan 12, 2023
    Frankster, Jan 12, 2023
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  7. Frankster

    Frankster Grey Pride...Adventure before Dementia Staff Member Premium Member Ride and Events Crew

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    I remember you telling me when the first USD fork was used on a bike when we were discussing MotoGP suspension a few years back. When was it again?

    upload_2023-1-12_10-42-17.png
     
    Frankster, Jan 12, 2023
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  8. Murdo

    Murdo The Good Doctor Staff Member Contributing Member Ride and Events Crew

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    1908 Scott had USD forks. Look to to things like BSA Bantam too.
     
    Murdo, Jan 12, 2023
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