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Tune up your chain device

Plated chain guides are simple enough. They rely on 2 plates to run either side of the ring to prevent the chain bouncing off. A pair of rollers sit to the rear of the device to keep the chain in between the plates. All that is required is a few minutes to get the setup right and you are pretty much guaranteed a hassle free ride.

First we look at a quick fitting tip for the chainline, then a mod to make 'em rock solid and last, a bit of preventative maintenance to keep things running smooth and prevent de-rails.

Fitting

"if you have a 68mm shell frame (as opposed to the 73mm type). Run a 73mm BB and you have 2.5mm spare per side"

Chain line is pretty important. Chain line refers to the offset from the rear cassette to the chainring. In theory, the middle of the cassette should line through with the middle of the chainring. Frame and crank manufacturers spend a lot of time getting this right. Then we go and lob 2-3mm of ally under the drive side of the BB and it all goes to cock. One area where you can claw some of this back is if you have a 68mm shell frame (as opposed to the 73mm type). Run a 73mm BB and you have 2.5mm spare per side - about the width of the plate you have introduced. Spot on chainline...

Also, make sure you Loctite (see article on this site) your roller bolts down as there come off really easily.

Lastly, spend some time shimming or adjusting the plates so that there a gap big enough to prevent rub on maximum gear shift but not enough to let the chain jump into.

Modifying

The plated devices rely on a inner 'boomerang' to hold the rollers in place. This boomerang is prone to 2 problems. First, if the BB is not super tight it can rotate around the shell. Second, the upper arm can flex in towards the frame, allowing a gap between the roller and the plate to open. If there is a gap, your chain will be through like a rat up a drainpipe and it's game over!

Presuming you have a seatpost on your bike, there is one simple mod that can prevent both of these happening. See the images below for more details but the basis steps are as follows:

You will need - a DMR seat clamp collar from your local dealer (find from UPGRADE), an M5 countersunk hex-head bolt (preferably zinc plated), a pile of M5 washers to fit the bolt (about 11mm worth) and a drill. This is the bit where you need to take care as drilling your £180 MRP is something you want to get right!

Fit the collar to the frame and line up with the boomerang. Mark the centre where you will drill your hole, leaving enough space to miss any mounting points. Remove the chain device and drill and countersink the hole. Make sure you countersink the OUTER face (the one away from the frame). Now simply refit the inner plate, loosely fit the countersink bolt and tighten down the collar. Shim the back of the boomerang with washers so the boomerang does not bend when you tighten down. Tighten the countersunk bolt and job's a good 'un.

Drilled and countersunk hole in plate	Fit the bolt to collar
Fit washers behind the plate	Tighten up - rock solid

Maintenance

These things get ragged pretty hard! It's good to keep an eye on the state of your plates to check for bends and the like.

One thing most people don't pick up on it the wear to the inner faces of the plates. Basically, as your chain drags on the plate, it picks up the ally into little peaks, a bit like a hyper glide cassette ramps. These peaks can get big enough to carry the chain right past the top roller.

This is easily cured by running a file around the inner face of the plates and removing these peaks. Doing this will help keep your chain device running sweet.

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