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Does dropping a bike hurt it mechanically?

Discussion in 'New Riders and Riding Tips' started by Danzotron, Apr 21, 2008.

  1. Hi guys,

    Just a newbie question.. not that I have dropped my bike yet, but I've always wondered if dropping a bike at low speed, like if you were in a carpark or something, does it actually hurt the bike mechanically? I kinda I guess I get the idea from when I tipped a 2 stroke mower upside down when i was like 12, and it never worked again because all this oil went into the fuel.. or maybe it was the other way around.. but does anything like that happen with a bike?

  2. Short answer is 'no' to the fuel/oil scenario. The slightly longer answer is that engines/gearboxes, main sub-systems, etc, on bikes are pretty robust, and damage usually is confined to the peripherals, like levers, lights etc. (Actually a human being hitting the ground is a fairly good analogy).

    But the long answer is; every single acciident/incident is different and there are no blanket rules....

    And if you had tipped MY mower up-side down when you were twelve you would have sustained some serious damage to your sub-system, if you get my drift :LOL:.
  3. Hahaha, thanks for the reply man. :)
  4. Normally no mechanical problems, but there are a few rare exceptions:
    - sudden stopping of the back wheel might hurt the gearbox/chain/etc
    - if left running on its side might cause the engine not to pump oil properly
    causing excessive wear
    - some early Hinkley Triumphs (the 1990's ones) would let excessive
    petrol into the engine and fill it up, causing damage if the engine was
    started while filled to the brim with petrol ('hydraulic lock'). This is rare.
  5. it is probably not what you are riding, but R series bmws can be interesting when put on their sides - you can shift valve clearances and crack the spark plug insulators.

    A big drop may also flat spot your steering head bearing races.

    In the main though, as long as you can't see the oil coming out of a hole in the engine, it'll probably be alright. Incidents where the bike rolls over can have exciting times for the rider when you forget to check if the brakes still work (getting air into the lines from the master cylinder intake port coming uncovered), but as many a dirt bike rider will tell you, if you didn't actually break anything, they'll usually just keep going!

    THe interesting thing in regard to dropping the bike is that from a drop perspective, it doesn't matter if you do it stationary or at 60km/h - the drop has the same impact in both cases. THe only thing that changes when moving is abrasion.

    One thing to note though, if your bike doesn't have a tip over sensor that stops the engine when you hit the pavement, don't let it run on its side too long or you can starve the engine of oil.
  6. define mechanically!?

    You can rip the front end off a bike, break it in half.

    It will never ride again and the suspension mechanicals are fcuked but the engine/box might be salvageable.

    Ti[pping over at slow speeds doesnt do much mechanically
  7. I was gonna mention this one. I've read a few ride reports where an early Hinckley Triumph engine's put a hole in itself not long after it's been dropped on 'the wrong side'.
  8. How else is he supposed to mow the ceiling?
  9. Upside-down mower = wood chipper ;).

    (On some 2-stroke engines you only need to relocate the fuel tank :-w ).
  10. the big thing ive been hearing around is the whole "all newbies will drop their bike so they shouldnt buy a new bike"
    after reading this thread im thinking the bike will only maybe get some scratches from dropping it?
    why is everyone destined to drop their bike?
    are we talking when its moving? or when its parked?
    as long as its not going to fcuk up mechanically, a few scratches deserves us right for dropping it i reckon..

    as long as the plastic isnt going to just completely break off
  11. Yep, but that one scratch will either cost heaps to repair, or drastically reduce the resale value of the bike (especially on a fully faired bike). Either way it ends up costing you money.
    Buying a bike that already has those scuff marks means someone else has effectively paid for any minor mistakes you might (and quite likely will) make.
  12. It depends on the bike.

    The VTR250, in all its naked beauty, will only get bent levers, scratched handlebar ends and (if it fall on the muffler side) a scratched muffler if it falls over when stationary. Sometimes a scratched ducktail if it falls over at slow speed.

    That's $10 to replace a snapped/bent clutch lever. Whooptie-doo. A new ducktail's only about $150-300 I think?

    Drop a nice and shiny fully-faired bike on its side and you're looking at the better part of $1000-2000 worth of plastic and paintwork. Depending on the weight of the bike and the manner in which it was dropped, it may only scratch the plastics, or it may crack/shatter them completely.

    This is why I recommend things like the VTR250 to learners - The insurance companies know how cheap they are to repair too - my Comprehensive insurance premium for a VTR was 1/3 that of a CBR250RR!

    Not necessarily "destined", but it can happen to the best of us. Inexperience, bad luck... Sometimes we forget to put the kickstand down. Sometimes we park badly and it falls on its side. Sometimes we put our foot down on a slippery surface and can't hold the bike up.

    S**t happens. :)


    I bought a pre-dropped VTR partly because it was a LOT cheaper despite only minor damage (scratched muffler, which I wanted to replace with a nice glasspack muffler anyway, scratched levers), and also partly because I figured if it had fallen over once, it had learned its lesson and wouldn't do it again.
  13. It's also a good idea to check your battery hasn't leaked any acid where it could cause corrosion.
  14. Big ends and bearings have been known to fail due to lack of oil, if the engine is left running. Use the kill switch.
  15. what about ogg nobs? and swing arm spools i think?!

    wouldnt they assist?
  16. ^ Oggy nobs do help.

    But if you look in the catalogue, you'll see there is no part numbers for most of the learner bikes. They generally only cater for the bigger bikes.
  17. if we say mechanical i assume you are talking about engine specific related components. short answer is no if the bike is not left running while on its side. you might get a stuck float in a carb, but this can generally be corrected by gently tapping the affected carb bowl. if this occurs all that is happening is that the corresponding cylinder is not getting fuel. i once rode my old VTR250 home 7 kms after a reasonable speed lowside, on one cylinder. she didnt like but still did it. the second cylinder kicked into life about 300m from home :LOL:

    other things? well i have seen mastercylinder caps ground down to nothing in "slowish" speed lowslides which of coarse makes the bike unridable.
  18. With my bike, if the tank is more than half full, you can expect fuel to start leaking out of the breather hole. The carb float also empties itself, so you have to crank for a while to start it up. Wouldn't be surprised if coolant and other fluids (eg battery acid, 2T oil) escaped through vent pipes too.