Motorcycle Top Boxes

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  • #16565
    DML1498
    Participant

    Good evening all,

    Just a general question regarding motorcycle top boxes, has anyone any knowledge of motorcycle collisions being as a direct result of a slightly overloaded top box i.e. weight limit 10kgs and it had 11kgs in it.
    I seem to think that 1kg is unlikely to have had any major impact on handling issues on a large engined high powered motorcycle.

    Any views on this subject.

    Thanks Dave

    #16568
    Andy Garden
    Participant

    Hi Dave, are you thinking of land distribution and moving weight from ihefront to the rear? if you are thinking of a solo rider + top box then unlikely to have any significant change, remembering that hopefully, the rider would take account of additional weight such as a pillion passenger, so a few Kgs in the top box is not really an issue.
    Are there any concerns in particular with your scenario?

    #16569
    DML1498
    Participant

    Hi Andy thanks for the response the motorcyclist in question was involved in a serious collision and eventually a friend of a friend has asked if the extra 1kg in the top box is most likely to have been a major contribution to the collision. It was a single vehicle and the central Armco barrier. My view was that such a small additional weight would not had adversely altered the handling. As you say a heavy passenger would have more input in the dynamics of the handling of the motorcycle.

    Thanks

    Dave

    #16570
    DML1498
    Participant

    Hi Andy

    Also forgot to say I was asked as the Police dealing with the collision have apparently prosecuted him for excess weight contributing to the collision.

    Dave

    #16572
    Andy Garden
    Participant

    The cynic in me wonders if the friend of a friend has not gilded things a little.Remembering our concept of a pillion, it would be fairly difficult to evidence that an odd kilo or so in the top bog either made the m/c overweight or it being a contributory factor to the cause. Single vehicle into a barrier probably has more about it than just a bag of sugar in a top box.
    The friend of a friend of a friend might like to suggest getting serious legal advise….NOW.
    Can’t see how we can PM on the new system for some broader suggestions without cluttering the forum.
    Kind regards
    Andy

    #16573
    DML1498
    Participant

    Hi Andy

    Thanks again my thoughts were along the same lines, just confirmation I guess from a third party.

    Regards
    Dave

    #16585
    Tom Lonsdale
    Participant

    I think there are multiple issues here. Firstly, to have any chance of a prosecution it would be necessary to establish from the top-box manufacturer the reason for the weight limit: it is just as likely to be governed by the load-bearing capacity of the rack to which it is mounted or the motorcycle sub-frame, or it could be the point at which the body of the box distorts and makes locking difficult. Secondly the idea that users routinely weigh their luggage before loading is preposterous, as would weighing a passenger, so the Police would have to have evidence that the rear of the bike was excessively loaded and in an unstable manner. As Andy has already said one extra kilogram is insignificant: if this rider crashed because of losing control he/she would have done so without that kilo, so other factors must be established.

    #16600
    Yuyo
    Participant

    Sometimes the topcase carries the weight behind the rear axle, which makes the front wheel have less grip if the weight is greater than allowed.

    #16601
    edwardhandley
    Participant

    Most top boxes are fixed above and behind the back wheel of the motorcycle so the weight distribution is very different to carrying a pillion passenger, and a inert weight does not move and lean into a turn like an experienced pillion passenger, so the two do not made a good direct comparison. Top boxes are either fitted to a carrier or come their own brackets which may allow some flex so it is possible that vibration or oscillation could build up which could effect the handling. However, a significant overload that affected the handling would quickly be obvious to even an inexperienced rider – I remember putting a 36lb case of dog food on the carrier of a Honda CB250 (when I was young and foolish) but I felt the difference in handling at once and moderated my riding till I got home.
    I do not think that 1kg over could be significant on a large motorcycle unless it was ridden at extreme speed. When you consider the weights regularly carried on small mopeds by provisional licence holders (i.e.untrained and inexperienced riders) doing food deliveries, it would take a lot more than a couple of kilograms to make a machine unstable!

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