• Question for ya all If the chain is slacker than it should be does it effect...

    Question for ya all.... If the chain is slacker than it should be does it effect the top speed?

    22 comments
    • No but it should not be too slack not fun having a chain come off

    • What's your slack measurement?

    • 2 inches of play at the tightest spot on the chain but I do it on feel also when adjusting make sure you adjust at the tightest spot otherwise you will have a way too tight chain and that is the thing that wears it down quickest.

    • 2" is good with the YSS (longer shock) but a bit much on a stock bike. Ideally you want to get someone who knows what they're doing to show you. Surprisingly difficult to get just right considering it's the most basic bike maintenance.

    • Will def affect speed and risk chain coming off, most bikes I've run seem about right at 30-35mm of slack, anything off road based will normally require a bit more

    • But when u do get it right, you do a few miles and it stretches again! It doesn't stay like it for long!

    • Could write a long boring lecture about how chains don't actually stretch.

    • I thought it affect the speed! I could tell the other day. It's stretched to about to 40mm

    • so why we adjusting then?

    • Used to easily knock 5mph off on my cub if it was slack!

    • They don't stretch, the pins wear out. The holes get bigger. Get a knackered chain and compress it, it will be shorter than new. Pull it straight it will be longer. Not stretched, but slack at the pins.

      This is why lubricating is essential as it stops metal rubbing on metal.

      If you over tighten a chain the process is accelerated because the grease is forced out when it's pulled tight by the suspension movement and you get metal on metal. If you pull it really tight you'll knacker the sprocket or output bearing before you 'stretch' a chain.

    • many thanks for that. I had no idea that's what happens. Where is the output bearing? I don't lubricate my chain because I like my bike to be clean and like new. Oil and grease make a right mess!

    • Output bearing is the one behind the front sprocket. If you don't lube a chain it'll rust, and not last long. Your cal what you prefer!

      Try wurth dry lube if mess is a concern

    • thank you, I have taken your advice.... Stripped chain scrubbed with wd40 and cleaned thoroughly, looks like a new one and applied 3 coats of the wurth product. I have a kepspeed swing arm and yss suspension set up. I have the chain at about 20-25mm slack, will this be ok?

    • Get a mate to sit on the bike, ideally he should hold it down so there is a straight line from the front sprocket to rear sprocket through the swingarm bolt. If there is still a little (10mm?) slack in the tightest point of the chain, then you're good.

    • if you sit on bike the chain goes super tight, which is the same for all bikes I guess. But when on the side stand it's about 25mm slack at tightest point, I think in the manual it does suggest to check chain the slack on the side stand.

    • Are you sat on the bike when you ride it? Will the chain then be too tight when you ride it? Only logic...

    • 20-25mm at tightest point is not sufficient slack.

    • the chains on all bikes are really tight when sitting on it? When pressure is taken off suspension because of bumps in road etc the chain then goes really slack, if it's too slack at that moment then it will come off. If I set it at 35mm it starts catching swing arm when bumps are hit. When It gets to 40mm it always hits swing arm and feels / sounds wrong. But when sat on it it's always very tight.

    • Your call, but if a chain goes tight at any point in the suspension travel then it won't last long. Promise.

    • But will it damage the engine / front drive sprocket stem etc. I don't want the chain dangling on swing arm causing scratches etc though. It seems that the smaller the engine the less slack the chain needs to be. I had a 50cc and it recommended 15mm of slack.

    • Have a look at it and have a think. With a short swing arm and relatively long suspension travel, the rear wheel arc will mean more change in distance from front to back sprocket as the suspension moves than on a longer swing arm not less.

      I've spent a long time typing the right answer. You seem to think you know better. If you ignore my advice and bust your chain and either or both sprocket bearing because you think you know better well then that's up to you. I'm done trying to convince you now.