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Chain Tension Adjustment


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Ok chaps and chapesses. this isn't a question per se, it's a "why havn't you done this already!"

So i was riding home from work. Gear changes were bad, i was getting false neutrals, gears jumping in and out and generally the bike was riding like a dog. under a slight amount of acceleration, there was a huge jerk before the power laid down. I was sure the gear box was knackered and i was going to need to replace it...

so i cracked out the tools today and checked my chain tension. 70mm, on the ybr, it should be between 20 and 30mm, that's a huge problem! i suspect with a bit of effort, i could have wrenched the chain off!! so here's what i did, for those who havn't checked recently, do it. it could save you the cost of a new chain or even a new gear box. DISCLAIMER: check the service manual for specifics relating to your bike. im not responsible for damage you do to your own bike. im not a mechanic, just a keen amateur.

1. If your bike has a centre stand, use it. if not, you will need a paddock stand. (coincidentally, the term paddock stand in relation to racing comes from the early days of motor racing. when no terminology existed, they pinched it from horse racing. horses stand in the paddock before racing...)

2. Clean you chain with some chain cleaner and a rag. spray the chain cleaner liberally onto the chain while rotating the back wheel to ensure an even distribution across the whole chain.

3. Use a rag (or a motivational t-shirt from a former employer) to clean off the gunk, grease and road crap from the chain. you might want to do this 2 or 3 times. DO NOT UNDER ANY CIRCUMSTANCES DO THIS WITH YOUR ENGINE ON, YOUR BIKE IN GEAR. recipe for finger loss.

4. find the tightest spot on the chain by rotating the wheel and using a rule to find the maximum deflection of the chain from a fixed reference. The best place is about half way along the swing arm where the chain would naturally move the most. Check your bikes service manual to find out where to measure from. on the ybr, it's halfway along the swingarm and the deflection you're looking for is between 20 and 30 mm.

5. if the chain requires adjustment, loosen off your axle bolt and the lock nuts on the tension adjustment bolt (at the end of the swing arm)

6. count the flats (one side of the tension adjustment bolt)and ensure you match the tension on either side of the wheel.

7. move the adjuster 2 flats, then check your deflection. keep this up until your tension is within specification.

8. once your chain is perfect, tighten your rear axle to the proper tension, you will need a torque wrench for this. The YBR i was working on was 80 Nm or 59 foot lbs (in old money).

9. lighten the lock nuts on the tension adjustment and check the chain deflection once more.

10.spray an even dose of chain lube first on the inside of the chain, then on the outside.

11.check the free play on the rear brake. on the ybr, it's 20mm play - your bike might be different.

aaaaannndd you're done!!

if you havn't checked your chain since taking it out the garage, do it. If (like me) you're an all year rider, it's imperative you check your chain at regular intervals. I might be teaching you all to suck eggs, but it's such a simple thing to do.

If you didn't understand the instructions, jump on youtube, there's a wealth of videos on there.

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Once you've done it once, it's nice and routine. I had a new chain on when I got my ybr, so it's been stretching a fair amount and I've done this 4 or 5 times now. First time was a nightmare, but now it takes five minutes :) I check my chain tension by pushing it up before I go out in the morning - only takes 10 seconds but is worth it. Good post :D

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I have a YBR and will be tensioning the chain soon, I've never done it myself but was done at dealers at first service.

Any chance of pictures to go with the excellent write up?

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I will be doing a service this weekend, depending on how fragile I am after the Otley run.... The chain tensioning will be part of that. If I can convince someone to help me, I will take some photos!

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