After a quick ride and a look over the bike - I noticed a few things might need attention before I took it off road for any serious distance. I am pretty mechanically minded, and service my own car and do minor repairs often. I have a decent set of tools, so I thought it was about time to learn a little more about MTB maintenance and repair. An $80 bike of eBay is the perfect place to learn, rather than risk stuffing up my nice new bike which is still under warranty.
So the list of repairs this bike will need to be deemed safe enough to put another family member on consists of:
- Pedals (it has none!)
- Rear wheel has play in it, probably need to tighten the bearings up.
- Broken spoke in front wheel needs to be replaced.
- V-brake brake pads are not aligned to the rims properly
- Rear brake pads are stuffed, need replacing
- Brakes don't seem to be releasing evenly on both sides, resulting in one pad continuing to rub the rim after release.
- The wheels are not straight - I believe my multi tool has something called a 'spoke wrench' and I assume I can somehow use this to straighten the wheels up
So the first thing I need to do is acquire any parts I need. As I don't want to spend too much on this bike, I measured up the wheel to work out the spoke length I needed, and hit that trusty source of cheap parts we all know and love - eBay.
I acquired 10 spokes and nipples for $2.63 and a set of brake pads for $7.50. A friend from work was putting in an order with Cell Bikes so I added a $7 pair of basic pedals to his order, and once everything arrived I was all set.
Now it is time to hit Google and work out what I am doing, and exactly how to fix each of these relatively common and simple problems. Below is a brief summary of what I learned and how I fixed each problem:
Attaching Pedals: Very simple, all you need is the correct size open end spanner or even a shifting wrench will do. The only trick is to know that both pedals are not the same, and will be marked left and right - so make sure you put the correct one on each side. The non drive side pedal (left) is reverse threaded. You may also want to smear a little grease on the thread to make it easier to remove the pedals if you want to upgrade in the future.
Adjusting Bearings: By 'play in the wheel' I mean that the wheel will have movement from side to side on the axle. The cause of this is either ruined bearings, or simply that bearings need adjusting because they are not tight enough. Riding a bike without properly adjusted bearings will cause earlier wear and the bike will be less stable.
The first step here was to confirm the type of bearings mostly used in a MTB. As I suspected a relatively simple 'cup and cone' type hub system is used in the vast majority of bikes. Here is a good link that has some pictures.
So with a shifter and one open end spanner - I loosened the lock nut and tightened the cone until all play was gone from the wheel. You need to be careful here - you want the cone just tight enough to remove play, but not too tight to compress the bearing so that it doesn't rotate freely. Spin the wheel once you have it right, and if it doesn't spin freely, it is too tight. Back it off a bit until it spins freely, but if there is play on the axle again you have gone too far. With some trial and error I got it right.
Broken spoke and truing wheels: Replacing the broken spoke was simple. First remove the broken spoke - the section still attached to the wheel rim just slid out, and I unscrewed the part attached to the rim from the 'nipple'. The nipples are the little metal components the spokes screw into, and are inserted from inside the rim. If you need to replace the nipple as well, you would have to deflate the tyre and remove it at least partially.
I didn't need to replace the nipple, so I just threaded the new spoke through the hub and screwed the nipple onto it at the rim with my spoke wrench. Pay attention to how the other spokes are threaded and follow the same pattern. Tighten at the nipple until the spoke feels roughly as tight as the other's.
One trick to remember when tightening spokes is that you are turning the nipple, not the spoke, so you rotate in the opposite direction than you usually would to tighten something. Just remember that you are turning the nipple, and not the spoke and this is easy enough, even though it may feel counter intuitive.
Once the spoke looks right - I had to 'true the wheel'. Now truing wheels is a little more complicated to explain, but basically you want the spokes on each side of the wheel to all be even so that the wheel spin's perfectly straight. You will know your wheel is not true if you spin it with the brake pad compressed to be almost toughing the rim, and one section of the rim touches the pad as it passes. My bike was so out of true after replacing the spoke that you could not spin the wheel with the brakes connected up.
The below video will make this clearer, and using this as a guide, and a bit of time and patience, I was able to successfully get both wheels in a pretty good state :
Brake Issues: V brakes are quite simple in the way they function, and easy to adjust. The below diagram illustrates the key components:
To replace pads you just remove the pad assembly with the correct size allen key, and fit the new pads. Pay attention to how the spacers and the assembly need to be installed as you are removing the old one.
Once I installed the new pads, I had to align all 4 of the pads to the rims. It is common sense that the pads need to contact the flat surface of the rim evenly. Simply loosen the pad with the allen key, apply the brake and position correctly, and then tighten into position. I found the pads often moved a little as I was tightening, so I had to take care to tighten slowly and to hold the pads firmly in place with my other hand. Remember you need to get 3 things right:
- The vertical position on the arm so that the pad is in centre of the flat edge of the wheel rim
- Flat on the vertical plane, so that the top or bottom of the pad is not contacting the rim first.
- Flat on the horizontal plane, although from what I read some people prefer to have the leading edge of the brake tough the rim slightly earlier, I would go with dead flat
The last thing I had to adjust was the brake arm centring. You want both pads to contact each side of the rim at the same time when you apply the brake, and release evenly when you release the brake. This is adjusted with the spring tension centring screws on each side (pictured above). Simply tighten the side you want to have more tension in the spring (or loosen the other). For example - if the left pad is contacting early, and not releasing from the rim - tighten this side.
That is about it - the bike is good to ride now - I am very happy with it for $80 plus about another $20 in parts, and I learned a lot fixing it up.
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