Motorcycles

Review: Chain Monkey takes the guesswork out of motorcycle chain adjustment

Chain Monkey gives you the perfect amount of slack when you're adjusting your chain.
Chain Monkey gives you the perfect amount of slack when you're adjusting your chain.
View 5 Images
Chain Monkey: saves a bit of faffing about in the garage
1/5
Chain Monkey: saves a bit of faffing about in the garage
Chain Monkey: precision chain adjustment
2/5
Chain Monkey: precision chain adjustment
Chain Monkey setup guide
3/5
Chain Monkey setup guide
Chain Monkey gives you the perfect amount of slack when you're adjusting your chain.
4/5
Chain Monkey gives you the perfect amount of slack when you're adjusting your chain.
Chain Monkey: small enough to fit under your seat, as long as you don't mind that it's usually covered in grime.
5/5
Chain Monkey: small enough to fit under your seat, as long as you don't mind that it's usually covered in grime.

It's dirty work, adjusting motorcycle chains. At least, it is on my bike, which gets cleaned exactly as often as it rains. There's also a bit of back and forth trying to get the right amount of chain slack - and that's where this jigger helps. Chain Monkey clamps onto your chain and gives you the correct chain tension first time and every time. Simple, effective and a good idea.

Generally, adjusting your motorcycle chain involves a bit of stuffing around. Play with the adjusters, check the slack, play with the adjusters again, damnit gone too far… Repeat until fingers thoroughly blackened with chain lube and sprocket grime.

My Triumph Speed Triple makes this process even worse; its single-sided swingarm uses an adjusting collar in behind the sprocket carrier, which needs to be adjusted in tiny degrees, but takes quite a bit of effort to move, so it's incredibly easy to overshoot the mark. You also tend to need to adjust the chain a lot, because … well, it's a Speed Triple, and it's very fond of preserving the front tire by holding it up in the air.

So I reckon this device might get a fair bit of action in my garage. Chain Monkey is a very simple idea that ensures a consistent correct chain tension every time.

Chain Monkey setup guide
Chain Monkey setup guide

Using a little table, you work out what setting you need to use for your chain and the amount of slack you need. The settings are weirdly far apart for something designed to help deliver precision, but you can work out exactly where it needs to be with a bit of thinking. You then set the Chain Monkey to that setting and wind up a little rubber ring to act as a stop.

Then you clamp it onto your chain, and wind it up to that stop, which puts a little bend in the chain - and then you simply adjust the chain until you can't tighten it any more.

Pull the chain monkey off, and presto, you've got the perfect amount of chain slack. Simple, consistent and effective. I quite like it.

Chain Monkey: consistent motorcycle chain tension every time

Two things, though. Firstly, don't leave the Chain Monkey on your chain and try to push the bike away, because it doesn't like that. Clearly this is something only an idiot would do. I did it the very first time I used it.

Secondly, the rubber ring stop isn't the best solution here. It can slip when you're doing it up on the chain itself, and that means you might find yourself dialling in too much slack. I'm going to pull this thing apart and replace that ring with a nylock threaded nut that'll stay where it's told to. It's odd Tru-Tension didn't use one of these to begin with, because they use a proper nut on the go-kart version of the Chain Monkey.

So there you have it. Simple jigger but a good idea. Could probably be executed a bit better, but in its current form it's still very handy. Is it worth the US$35/AU$65 pricetag? I guess that depends on how much chain adjustin' you do.

Product page: Tru-Tension/XenonOz

5 comments
Buellrider
Since you have to centralize the wheel by adjusting from both sides of the axle it probably is a bit harder to get right than is show in this article and the video. Seems like a spring loaded version where you'd quit tightening when the deflection straightens out would be a better way of doing it. Buell motorcycles took the guess work out with their no adjustment setup and belt. Way better solution except for hot rodders where a chain is better for handling the extreme hp and tq.
zr2s10
Neat idea, but suspension compression was what got me once on my Polaris Scrambler. They say that it has a "concentric swing-arm", which is supposed to mean that the chain doesn't tighten as the suspension compresses. Not true. One time when I hit a jump, my chain snapped from over-tension, and busted my transmission case. Now I use a ratchet strap to compress the back end, then make my adjustment. That and a spring tensed roller help keep the slack right, and the chain on the sprockets.
PeteKK
I guess this is OK for someone that doesn't know how to adjust a chain but the reality is that all you need to do is lightly pull up on the bottom center of the chain with one finger until it stops just a little bit before it touches the bottom of the swing arm. No magic little gadgets required... just some, not so common, common sense.
Simon Payne
Heigh ho.. Nice idea, but yes exposed chains are dirty noisy and inefficient, except when new and well lubricated of course. It seems hilarious to me that modern bikes still have these crude things on them, especially considering the cost. A Ferrari owner would never put up with it.. Frankly I would not buy another bike with a chain, ever! Ride safe Si.
Bill Bennett
Loz, Next time save your hands and wear nitrile gloves.
Thanks for reading our articles. Please consider subscribing to New Atlas Plus.
By doing so you will be supporting independent journalism, plus you will get the benefits of a faster, ad-free experience.