Sprockets second hand bike

Discussion in 'Transmission / Drivetrain' started by zippinaround, Aug 4, 2013.

  1. zippinaround

    zippinaround Active Member

    hi there everyone! i recently bought a second hand moto bicycle i think its a china girl not positive though! i have a few questions hopefully someone can answer. i noticed the rear sprocket was not properly centered so i took it off and realised one of the rubber rings was not flat but very uneven which i assume is not normal my first question is can i buy just 1 new one? second question is the sprocket is dished and was fitted with the dished side in so was very close to the spokes is this the right way?
     

  2. crassius

    crassius Well-Known Member

    when mounted for a while, those rubbers can squeeze down in places and even get cut thru by the spokes - best to replace them as a pair

    as far as dishing in or out, I usually look to see which way will clear both tire on the inside and frame on the outside as each bike is a bit different back there
     
  3. bluegoatwoods

    bluegoatwoods Well-Known Member

    Well, let's see.....I honestly don't remember which way I turn the 'dish' of my sprockets. But dishing toward the spokes is probably best in most cases. That ought to help avoid chain rubbing the chainstays.

    As for the 'donuts'. One that has been installed on a bike will surely have indentations where it had been clamped onto the spokes. But that can't be what you're asking about; you'll have already figured this out. If they're a bit warped, then I wouldn't worry. They'll be flattened out when installed.

    And you can get parts, if needed, from the various vendors around. Sponsors of this site would be a good place to start. I hate to think what shipping to Ireland might cost. But maybe there are European vendors.
     
  4. zippinaround

    zippinaround Active Member

    ok well instead of buying a new donut and waiting for delivery i just trimmed the uneven bits with a stanley knife (i'm not very patient) refitted the sprocket dished out and it seems to be a lot straighter although the chain is now quite close to the frame but i rather a rub off the frame than to ruin my spokes! ya there is a few places around that sell the kits but they wont sell individual parts which is annoying! also does anyone elses bike sound like its dragging a bunch of tin cans around when just cycling??
     
  5. crassius

    crassius Well-Known Member

    something rubbing? chain too tight?

    rear sprocket is never perfect, so chain must be adjusted while at its tightest location on the sprocket
     
  6. zippinaround

    zippinaround Active Member

    it sounds like its coming from the cylinder so maybe a bearing in the engine! bad idea buying a second hand bike i think doesn't seem to be built very well . i have a smaller engine thats automatic might be better off building one with that engine
     
  7. crassius

    crassius Well-Known Member

    what did you mean by 'just cycling"?

    I took it to mean riding the bike without the engine engaged.
     
  8. zippinaround

    zippinaround Active Member

    yes thats what i meant engine off i only use the engine for going up hills. when the engine is off and clutch pulled if i just move the bike 1 inch forward or backward theres a knocking kind of rattle from the cyclinder sounds kind of like the piston rattling around in the cylinder??
     
  9. crassius

    crassius Well-Known Member

    the piston should not be moving at all - I'd guess the noise is from chain or clutch
     
  10. zippinaround

    zippinaround Active Member

    possibly the clutch. maybe i'll make a little video later as there is a couple of things i'd like suggestions on!
     
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