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Bike weights and regs

  1. #1
    Lifer Kurlon's Avatar
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    Bike weights and regs

    Rather than further pollute the DR350 thread, I figure this is an interesting enough topic to discuss on it's own. Some people are throwing Sur-Ron e-bikes into dirt races and doing decently, which shows the potential of lightweight electric dirt toys vs our heavy gas to go conversion devices.

    But do our gassers have to be that heavy? Currently MX targeted products are made with an expectation that a decent number of them will be raced, and that means AMA or FIM derived rules are likely in play. Both have minimum weight requirements, and production / homologation rules so to be in the game the MFGs have to be mindful of these rules when designing a bike. No point making a bike way under the min weight if it can't then be raced. (Both orgs disallow the use of 'ballast' in any form to bring a bike's weight up to minimum.)

    For discussion, these are the numbers, measured without fuel.

    AMA minimums:
    - 250 class - 2 stroke 194lbs, 4 stroke 212lbs
    - 450 class - 2 stroke 212lbs, 4 stroke 220lbs

    FIM minimums:
    - 65 class - 117lbs
    - 85 class - 65cc to 85cc 2 stroke 139lbs, 100cc to 150cc 4 stroke 157lbs
    - MX1 class - 175cc to 250cc 2 stroke 216lbs, 290cc to 450cc 4 stroke 218lbs
    - MX2 class - 100cc to 125cc 2 stroke 194lbs, 175cc to 250cc 4 stroke 209lbs
    - MX3 class - 290cc to 500cc 2 stroke 225lbs, 475cc to 650cc 4 stroke 225lbs

    My 150SX for example, toes the line at 194lbs dry. Suzuki was racing 187lb 250cc machines in the early 70s prior to the weight rule (and were a primary reason for the adoption of such a rule) so it's not the current state of tech holding us back from lighter bikes. Is it time to get the AMA / FIM to lower the weight minimums so we consumers can reap the benefits?

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  2. #2
    Lifer
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    Re: Bike weights and regs

    Is your 150 at 194lb wet-minus-fuel, or totally dry? Probably a couple pounds in coolant, tranny oil, and hydraulic fluid.

    If they really could be lighter, but no point because of no ballast, I'd figure they'd still engineer the lighter bike for the trail/gncc crowd and sell their MX-trim bike with a thicker casting head, or thicker wheels etc. Or leave the kick starter on the bike, when they install a starter. We see they aren't doing that one.

    edit: "Devices designed solely for the purpose of reducing wind resistance may not be attached to the rider’s apparel." (Source, pg 18/34)
    In reality, does that essentially ban going full spandex?

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    Last edited by aldend123; 10-22-19 at 05:51 PM.
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  3. #3
    Lifer Kurlon's Avatar
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    Re: Bike weights and regs

    The owner's manual says 'Weight without fuel, approx - 87.5kg / 192.9lbs'. FIM allows a 1% tolerance, so that's right at the line for MX2, but only matters for the 125SX as the 150SX isn't FIM legal for anything. (Same weight for both.) Also, most other brands list weights right on their sites, don't make me dig up owner's manuals for this KTM/Husky(/And now GasGas...)

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