The transmission is one of the parts of the bicycle that must be checked most frequently, due to the friction and continuous wear of all its components. In addition, a failure of some of them – sprockets, chainring, derailleurs or chain – entails a great expense since they are not cheap parts and the poor condition of one ends up affecting the others.
For this reason, it is advisable to periodically check the state of the transmission, as well as correct lubrication and maintenance.
The good thing about transmission overhaul and maintenance is that you can usually do it from home and it’s easy. Carrying out the check correctly and on time will prolong its useful life for a long time, it will work as it should and you will avoid costly repairs.
Review streaming from home in 6 easy steps
Each step of the review will be focused on a component or parts of the transmission, so that the check is complete. Here we explain how to check each component and how often to use it.
String: after each outing
It is the component of the transmission that must be cared for and checked the most. Its condition should be checked after each outing, especially if you practice off-road cycling, such as mountain biking or gravel.
If it accumulates dust or traces of mud, it must be cleaned. First with soap and water or with a degreasing spray, dry it and re-grease it, either with oil or wax lubricant .
An essential tool that you should always have is a chain wear gauge.
In addition to its cleaning and lubrication, you should check the elongation of the chain. With use, the chain links wear out and the chain lengthens, increasing friction and wear between it and the chainrings and sprocket teeth.
That is why it is very important that you get a chain gauge and use it at least once a month to see the evolution of its wear. If the tips of the 1% gauge (1.0) go completely into the hole in the links, you will have to replace the chain with a new one and also the cassette. In this video by Macario Llorente that we share, they explain in detail how to use this meter correctly:
Plates, crowns and sheaves: once a month
The next point is to check the condition of the chainrings, pinions and sheaves. Check that the teeth are not dirty or accumulate dust or traces of fat. If not, it should be cleaned thoroughly with soap and water or applying a degreaser. It is convenient to review them, at least, every fifteen days or a month.
Diverters: once a month
One of the points to which more attention must be paid, since the correct change from one sprocket to another or from one chainring to another depends on them, are the derailleurs. Check the rear derailleur first. Check that the upper pulley on the derailleur hanger is aligned with the smallest crown and also with the largest one, to avoid chain pulls or pulls .
If it is not aligned you will have to tighten or loosen the screw H of the derailleur for the lower stop (smaller crown) until it is in the correct position. Screw L, located next to H, will serve to align the sheave with the larger crown.
At the same time, check that the derailleur leg is not bent. If it is, the rear derailleur will need to be removed and straightened. In this case, it is better to ask a mechanic for help, who will have the necessary tools for it.
For the front derailleur, the alignment with the chainrings is done in the same way as for the rear. By tightening or loosening the respective screws H and L we will adjust the precision of the chainwheel change and prevent the chain from coming off. It is also worth greasing with a drop of lubricant (if it is for better dry conditions) the turning points of both derailleurs, every month or two months.
Cranks: once a month
One of the most frequent problems of a transmission malfunction, a reason for annoying noises or creaking sounds during pedaling, is the play of the cranks. To check that they are properly tightened, you can pull them towards you perpendicular to the direction of travel.
The manufacturers of connecting rods recommend a preventive tightening of the same every 200 km traveled. But so you don’t forget, add this check to the monthly or bi-monthly check we recommend for components such as chainrings, sprockets or derailleurs.
Bottom bracket: once a year
As for the bottom bracket, it is advisable to do an internal cleaning (bearings, bearings) and lubrication at least once a year. In the case of mountain biking or after winter, external agents such as water, mud or dust can get inside the axle and damage it, making extra cleaning necessary.
Pushbuttons and wiring: once every two months
The penultimate step of the check is to check the condition of the shift knobs and cables. For the former, check that the levers move correctly on their axis and have no play. Also that with each movement of this click and change the crown and plate.
If it does not click or change, you will have to open the push button cover, apply spray degreaser and re-grease the mechanism with liquid lubricant. Chain lube may work, but don’t over-apply it. This will allow the pushbutton pawl to be free of debris and to move properly again.
On the other hand, checking the condition of the cables and gear covers is very important. Get a check-up every two to three months of use, or after the winter or summer season. The existence of scuffed or cut covers will make it necessary to change these for new ones. Misadjusted and inaccurate gear shifting may be due to worn cables, which will need to be completely replaced.
Pedals: after every ride
Finally, do not forget to check the pedals, both the lubrication of their springs and the setting mechanism (without they are automatic) and their tightness to the crank. After each ride, or after washing the bike, you should apply a drop of lubricant to each of the pedal springs.
Second, check that they are tight, as otherwise it may cause annoying noises due to looseness. We recommend that you remove the pedals, grease the threads of the crank and that of the pedals with mounting grease and reinstall them every two months if you have ridden frequently.
Remember not to overdo the pedals, as they tighten themselves when pedaling and it will be very difficult to remove them in the next revision.
Frequent Transmission Faults and How to Fix Them
The following are the most common problems that can arise if the transmission is not properly maintained:
Rusty chain
It is not very difficult for the chain to rust and it can happen even without being worn or elongated. If you have gone out with your bike on a rainy day and once the route is finished you have not cleaned or greased the chain, the rust will begin to appear superficially.
If rust appears on the chain, clean it thoroughly with a degreaser. There are brands of lubricants that even have specific cleaners to remove rust. Let the product act for a few minutes and then rub the surface of the chain with a fine wire brush. Then rinse with water, dry the chain with a cloth and lubricate it again. If there is a lot of rust accumulated, you will need to replace the chain with a new one.
Mismatched shift
It is one of the most common breakdowns, the result of the use of the bicycle itself. The shift cable tends to loosen over time. Any blow to the derailleur or the derailleur leg will cause jerks, jump to another crown or not shift when up or down gears.
To prevent this, you can adjust the tension of the transmission cable yourself from the cable tensioner wheel, usually located in the cable connector with the push button. On road bikes it is usually placed at the height of the head tube. Turning the tensioner clockwise will loosen the cable so that the crowns lower better. On the other hand, for the crowns to rise correctly, you must turn the tensioner in an anti-clockwise direction.
However, cable tension is not the only reason for a derailleur malfunction. It may also be because the derailleur foot is bent or the derailleur is not correctly aligned with the larger or smaller crown on the cassette. In the latter case, you will have to tighten or loosen the screws H and L of the front derailleur, as we have explained above.
Broken teeth
A more serious fault is the breakage of a tooth from a plate or crown, the result of the impact of a stone, a fall, etc. This can lead to chain skipping and runout, inaccurate crown changes, etc.
It will be necessary to replace the affected crown with one of the same number of teeth. Same situation for the plate. Do not delay its replacement, otherwise the transmission will not work as it should and will accelerate the wear of the chain, the cassette and the chainrings.
