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Auto chain tension

Discussion in 'Bling and Appearance' started by dougster, May 2, 2007.

  1. Just a query for the mechanically minded.

    If bicycles can have an automatic (spring loaded?) chain tensioning devices, then why don't we have that for motorcycles?

  2. don't really know but perhaps the greater forces involved with motorbike engines and weight have something to do with it...ei spring might not be anywhere near strong enough.
  3. I've pondered this myself.

    All that really comes to mind is;
    * Chain tension would go /crazy/ when you engine brake. On a badly lubricated or worn-out chain on a bicycle, it is possible to "bork" the autotensioner by backpedalling quickly. Now imagine that with a 500cc motor "backpedalling" for you as you engine-brake. :)
    * Additional sprockets to replace when chain wears out (cost)
    * Additional mechanical complexity (cost)
    * Chance that the mechanism required could not withstand the loads exerted by the bike motor without the sprockets being prohibitively large and heavy.

    I believe the main issue is the reversal in tension when engine braking. The other factors are the icing on the cake. Shaft drive is a much more elegant way to avoid the issue of chain wear. :)

    'course, the reason bicycles have the 'auto-tensioner' is so that the chain can be guided around the different combinations of gears. It simply absorbs the "unused" length of chain.
  4. Bugger that., It's enough that the chain has to round 2 sprockets at the moment. I'd hate for anything to happen to an additional component at speed.
  5. cam chains and belt drives have no problem with 'reverse tension'

    chains put up with a lot of variation in slack with no problems

    additional tensioning gear is heavy, expensive and pointless.

    a good chain will only need tensioning at normal servicing intervals, if at all.