Stills taken from our 'gear set up and maintenance' instructional DVD which is available for £3.97 from our ebay store
Not having yours gears set up correctly is one of the most annoying problems you can have on a bike. The most common symptoms of a poorly set up system are hesitation on shifting, slipping or jumping gears, and noisy operation, all of which are guaranteed to ruin what should be an enjoyable ride – but don’t despair modern gear systems are pretty easy to master these days – so by the end of this guide you should have everything running sweetly and smoothly.
When dealing with gears it can be confusing when reference is made to 'high gears' and 'low gears' - so here is a recap before we start.....
For the front derailleur 'low gear' = the smallest chainring and 'high gear' = the biggest chainring. For the rear derailleur 'low gear' = the biggest cog and 'high gear' = the smallest cog.
Now before you remove your old cables the first thing to do is familiarise yourself with how and where they are routed, you might even want to take some photos as this will serve as an easy reminder for when you are fitting the new ones. At this point you also need to set the rear derailleur to the smallest cog and the front derailleur to the smallest chaining
If your gear cables are routed underneath the handlebar tape then remove this first by cutting the insulation tape on the stem side and unwrapping the tape. If you’re on a budget then you might get away with re-using the old tape if your careful taking it off, but most of the time its easier just to use new tape.
To remove the cable snip off the end crimp with some cable cutters, and undo the cable clamp - which is usually a 5mm allen bolt, this will then release all the tension in the cable, and allow you to take off the cable housings. Take care not to lose the ferrules from the end of the housings. Peel back the lever hood to reveal the cable exit hole and this will allow you to pull the cable out. Then its just a case of completing the same operation for the front derailleur
CUTTING THE NEW CABLE HOUSINGS TO SIZE
If you were happy with the routing of your old cables then you can use them as a template for cutting the new ones. This is also where a specialized cycle cable cutter scores over standard pliers as they don’t squash the housing as much in the cutting process. Nevertheless, it's still a good idea to make sure that the end is nice and round by using the indent in the cable cutter which is designed for this purpose. You also need to make sure that the inner liner does not obstruct the cable by poking a small nail or something similar into the housing end to open it out. As a final check make sure the cable runs freely through the housing, and then place a ferrule on each end.
One point to note here is that brake and gear cables are not the same, so make sure you ask for cables and housings which are designed specifically for indexed shift systems and check that they are compatible with your make of gears.
FITTING THE NEW CABLES
Once you have cut the housings to size fitting the new cable is simple enough. Start with the rear derailleur first and make sure the index shifter is clicked all the way out (as if you were changing onto the smallest cog) this will then reveal the hole in the lever for the cable to thread through. Thread the end of the cable through this hole and then pull all the cable through, making sure the cable head seats properly in the lever. Then it's just a case of threading the correct housing segments onto the cable and routing the cable in the same way as the old one, and dont forget to thread the cable through the plastic guide under the bottom bracket shell.
Once at the derailleur you need to thread the cable through the adjuster barrel and cable clamp, and make sure that the housing seats nicely into the adjuster barrel. Before you tighten the cable clamp make sure that the adjuster barrel is screwed almost all the way in. Sometimes there is second adjuster on the frame, so if you have one, do the same with this. Pull the cable lightly with some pliers (so there is no slack in it) and then tighten up the cable clamp bolt. Finally, snip off the cable end 4-5cms passed the cable clamp, and then to stop the cable fraying squash a crimp on the end with the blunt part of your cutters. Leaving 4-5cm of cable passed the clamp will give you enough spare to allow you to remove and replace the cable a few times for thorough lubing – but do make sure is will not foul or catch on anything.
Before you fit the front derailleur cable it’s a good opportunity to check its aligned correctly. Basically what your looking for is the outer plate to be sitting 1-2 mm above the big chainring, and then sighted from behind the cage it should be exactly parallel to the chainrings. If yours is not set correctly it’s just a case of loosening the band clamp bolt and this will allow you to make the necessary adjustments.
Fitting the front derailleur cable is the same process as the rear but this time you will only have one cable housing to thread on. Don’t forget to screw the adjuster barrel on the frame all the way in and then back half a turn before fitting the housing. Once at the cage thread the cable into the cable clamp, making sure it's seated in its groove properly, and then pull the cable tight with a pair of pliers before tightening up the clamp bolt. It’s important that there is no slack in the cable because the cage needs to move as soon as you start to move the shifter
ADJUSTMENT OF THE FRONT DERAILLEUR
Assuming the front derailleur is aligned correctly the only thing that you may need to adjust is the high and low gear limit screws which are located on the top of the derailleur body. The purpose of these two screws is to stop the chain from being thrown off the inner or outer chainrings as you change gear by limiting how far the cage is allowed to move. Once they are set right your should never really need to touch them so if your front derailleur has been shifting okay (and the chain doesn’t come off the chainrings when shifting) then just leave them well alone.
If you are having problems then the first thing to do is identify which screw is which. The low gear limit screw is usually the one closest to the frame or is sometimes labelled with an 'L' - this controls where the derailleur cage stops when changing onto the small chainring.. Adjusted too far and the chain will come straight off the small chainring. To remedy this turn the screw a 1/4 turn clockwise and then try again - if the chain still comes off try another 1/4 turn and repeat until the change is secure. If it’s adjusted too far then this will stop the chain moving easily onto the small chainring so to remedy this turn the limit screw anticockwise a 1/4 turn at a time until you achieve a smooth and easy change.
For adjusting the high gear limit screw (sometimes labelled with an 'H') try changing onto the big chainring - if the chain is pushed right off the chainring then turn the limit screw a 1/4 turn clockwise and try again until the change is secure. If the chain has trouble changing up to the big ring then the limit screw is set too far in so back it off a 1/4 turn and try again until the chain changes up easily
ADJUSTMENT OF THE REAR DERAILLEUR LIMIT SCREWS
Before adjusting the rear derailleur it’s a good idea to make sure the chain, chainrings, and the derailleur body have been thoroughly cleaned and lubricated. When setting the rear limit screws the same principal applies as for the front derailleur – that is, if you haven’t been experiencing problems with shifting, or the chain hasn't been coming off the rear cassette, then leave them be – because once set correctly the limit screws should never really need touching.
If you do need to make an adjustment then the low gear limit screw is usually the one furthest from the frame or labelled with an 'L', and when you are making adjustments to this screw make sure you have the chain on the small front chainring first. This screw adjusts how far the derailleur can go towards the spokes and therefore stops the chain from coming off the big sprocket and crashing into your shiny expensive wheel. If it's adjusted to far you will be also be able to sight this from behind and see the top jockey wheel out of line with the big cog. If its far enough out of line the chain can be pushed off the big cog – which can be both expensive and dangerous. To remedy this turn the low gear screw clockwise a 1/4 turn and try shifting again, repeat until the chain stays securely on the big cog. If its not adjusted far enough then this will prevent the chain from changing up to the big cog at all (or at the very least cause it to hesitate) so to remedy this do a 1/4 turn anticlockwise and try the shift again. Repeat this until it changes up smoothly without hesitation.
The high gear limit screw (sometimes labeled 'H') does exactly the same job but for the smallest cog, and before adjusting it you need to make sure the chain is on the big front chainring first. The same principals apply so if the cage is too far out of line with the small cog its likely that the chain will go straight past the small cog on onto your nice dropout, so 1/4 turns clockwise on the limit screw until the cage is back in line should sort it out. Finally, if the derailleur will not change onto the small cog at all then this is likely due to the limit screw being set too far in - so this time it's 1/4 turns anticlockwise until the shift is quick and smooth.
If you are unsure whether it's the limit screw adjustment that is causing your shifting problems then keep a note of how many turns you have made on each screw. If they do not remedy the problem then at least you can return them to your original starting position.
REAR DERAILLEUR CABLE TENSION ADJUSTMENT
Okay, so now we are onto the nitty gritty of gear set up and this is a task that alot of people shy away from tackling because, for some reason, they perceive it to be some sort of black art. In actual fact it's very simple just so long as you are patient and methodical in you approach.
The first thing to do is make sure the chain is on the big chainring at the front, and the small cog at the rear. It's also important that the cable has been let out all the way so keep clicking the shifter until it wont let any more cable out. Now try clicking the shifter once to change to the second cog - if all is well then the chain should change quickly and smoothly, if it doesn’t (or it hesitates and/or makes a racket) then unscrew the cable adjuster barrel anticlockwise a 1/4 turn and try again. Repeat this until it changes up smoothly. Incidentally, if you have an adjuster barrel on the frame as well then this will perform the same task. The reason why it's there is simply to allow you to make fine tuning adjustments as you are riding along.
If the chain is overshooting the second cog completely when you change or makes a noise when it’s on the second cog then screw the adjuster barrel in by a 1/4 turn, try again, and repeat as necessary until you get a nice change. Now try changing up and down the first few cogs. If one of the changes isn’t quite right fine tune the adjuster barrel as before and try changing up and down again to check they all change smoothly.
The next thing to do is to shift the chain onto the smallest chainring at the front and the biggest cog at the back and repeat the same process making sure that it changes precisely across the two biggest cogs first, and then over the whole rear cassette – making fine adjustments on the adjuster as necessary. If you happen to run out adjustment on the adjuster barrel then first screw the barrel almost all the way back in, undo the cable clamp bolt, and then pull any slack out of the cable.
If your still a bit confused about exactly what is causing what to happen with derailleur adjustment then don’t be frightened to have a good play about with the adjuster with the chain on a middle cog - it's a good way of helping understand what’s going.
The last thing to do is to go out for a ride and see how the gears perform under load, as this is always the best way of highlighting any final tweaks to may have to make. If are still having shift problems after patient adjustment then it's time to look at other possible causes. A bent derailleur hanger, worn chain and sprockets, or a misaligned frame can all cause shift problems.
One important thing to understand with derailleur gears is that no matter how well they are set up you are unlikely to ever get perfect shifting in 'extreme gears'. By 'extreme gears' i mean when the chain is on the big ring at the front and the biggest one or two cogs at the back because this pulls the chain too far out of line for efficient shifting. The same goes for when the chain is on the small ring at the front and the smallest one or two cogs at the back. It's also just good practice not using extreme gears when riding because this avoids putting excess strain and wear on your drive train.
GEAR CABLE CLEANING AND LUBRICATION
The same principals apply for gear cables as for brake cables, that is if you have just fitted new ones then there no need to lubricate them because they come pre-lubed. It’s only when they have been subjected to some of our lovely winter weather you will need to start lubricating them with a light cycle. The main one to concentrate on is the rear derailleur cable because this is much more prone to getting clogged up with dirt - which will inevitably cause shifting problems.
To do a thorough lubing job make sure your on the big ring at the front and the small cog at the back, then snip off the end crimp and remove the cable housing. You can then unthread the cable up to the handlebar housing which will then enable you to give it a good wipe down with a rag followed by a coating of cycle oil. A good way to clean the housing is to blow all the dirt out with some spray lube, and then finish off with a few drips of oil. Don’t forget to clean and lube the bottom bracket shell cable guide as well. Then its just a case of rethreading the cable taking care not to fray the end and then refit the housing and cable and go through the adjustment procedure described above.
If you feel your front derailleur shifting is starting to suffer from a clogged cable then you can perform the same lubing operation for this cable as well, and then to finish off just lube all the front and rear derailleur pivots more good measure.
One final thing - avoid using dry lubes or wax-based lubricants on cables and housings as these will quickly turn into a sticky paste which will restrict cable operation and ultimately cause shifting problems.
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You can also see exactly how it's all done in close-up detail with our easy to follow step by step DVD, which is available from our ebay store - just click on the link below.