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Hello is there anyone that is able to help me? I need to get a new chain for my little boy's quad bike and I'm unsure on what size I need to get.

Its a 50cc mini motor quad bike. I have looked online but says all different numbers of links and the one that is on it already is too small as I bought it off some bloke who didn't have a clue what he was doing.

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    Hi, welcome to bicycles! While we do accept questions about vehicles with more than 2 wheels (like trikes), purely motor-driven vehicles aren't on-topic for this forum. You might try on Motor Vehicle Maintenance & Repair instead.
    – DavidW
    Aug 21 '19 at 19:58
  • You probably need to measure the chain links. Which can be a little tricky. Aug 21 '19 at 20:05
  • @DavidW concur - but there's still a chance this uses bicycle chain, cos its cheap. I've tried to answer in that vein.
    – Criggie
    Aug 22 '19 at 10:50
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    I'm voting to close this question as off-topic because it is about motor vehicles. Aug 22 '19 at 21:25
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From a little research it would appear most Mini Moto Bikes & Quads up to 50cc mostly use a 25H or 25E chain. They vary in price depending on retailer but most seem quite easy to buy being a popular item. As we know very little else regarding main drive dimensions (cog / gearing) apart from the fact it should only consist of a main drive gear and a smaller one on the rear axle.

All I can do is attach a chart of the most likely chains and the OP can hopefully work out what chain is required according to the dimensions on the gearing. Most Likely Compatible Chains

Chain Stamped 25H

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  • Yeah I was tempted to start going into all this when writing my answer, but as soon as its not bicycles, then its off-topic for here. Probably OP should repost this in mechanics.se ?
    – Criggie
    Aug 31 '19 at 0:01
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First up - confirm that its Roller Chain. There's a metal doughnut roller around each pin in this example:

enter image description here If it doesn't look pretty close to this, then its not bicycle chain.

Then check if its a bicycle chain. The pitch will be exactly 1 inch / 25.4mm per pair of inner+outer links, with maybe up to 1-2% longer if its worn. This is the same as saying 0.5 inches between adjacent chain rollers/pins.

Any other chain pitch and you're looking at a motorbike chain.

Then move to measuring the width, between the inner plates.

  • 1/8" (0.125", 3.18 mm) chain is used on most single-speed bicycles, and this would be my guess.
  • 3/32" (0.094", 2.30 mm) chain is used on deraileur equipped bicycles.

Again if its not one of those two, you have motorbike chain, or possibly something different again.

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