1. Seized threads/pressed in fittings
So you're tearing down your bike in your garage and one of pieces you need to remove from your frame is stuck. Like really stuck. Do you know why? Chances are the culprit is corrosion. The most common example of this often happens with seatposts. Many seatposts are made of aluminum, and unless your frame is also made of aluminum, it is likely to become subject to galvanic corrosion. This even applies to an aluminum post in a carbon frame, or the opposite. When you have two different materials with different amounts of electrode potential and introduce an electrolyte, galvanic corrosion occurs. Sweat is basically salt water, which is an awesome electrolyte. Over time, sweat will get into every crack and crevice in your frame. If that doesn't do it, road salt, and other sources of water will eventually do the job. Once a part is seized in your frame, almost all methods of removing it carry a substantial risk of damaging your frame, and the part is almost certainly ruined. The best way to avoid damaging your frame is to not allow the parts to become seized in the first place. This is accomplished by using a proper anti seize before installation.
Anti seize guide:
Aluminum on Steel: Good old fashioned grease does the trick.
Aluminum on Titanium: Copper based anti seize paste.
Carbon on anything: Carbon assembly paste
Aluminum on Aluminum: Grease
Why use grease on an aluminum on aluminum fitting? Because they might be different alloys of aluminum, which could cause them to have different electrode potentials.
Spread the anti-seize compound listed above lightly but completely coating the entire inside of the female side of the junction. For threaded parts, apply to the male threads from end to end liberally and install the part, then wipe off any excess.
Follow this guide and you should have no issues with seizing parts.
2. Pinch Flats
So you're out for a ride you hit a little bump and you hear the dreaded hiss of a flat tire. You look down and your rear tire is flat. When you go to change it, you notice that the tube has two punctures on the inside of the tube that faces the rim! There aren't any signs of puncture in your tire. You have managed to get a pinch flat.
A pinch flat occurs when the tire compresses when hitting a bump and it compresses so much that it pinches the tube between the tire and the rim. This results is the tell-tale "snakebite" pattern of two closely spaced holes in the tube on the rim side of the tube. Many people that come into the shop see this and think that something is wrong with their rim, that there is sharp burr in there or something is defective about it.
The true cause of pinch flats is under-inflated tires. Bicycle tires are not like car tires. They lose air over time. How long it takes for the tube to lose enough air to be at the point where you are risking a pinch flat depends on the size and optimal operating pressure for the tire, conditions, and rider weight. The heavier you are, the more pressure you need to have. The skinnier the tire, the more pressure is needed. The rougher the terrain and harder you ride, the more pressure is probably needed. Make a habit of checking your air pressure before every ride and topping off the air if necessary. Doing this will help you avoid pinch flats. You can still pinch flat with properly inflated tires if you slam the tire into an obstacle like a pothole or large rock very hard but it's much less likely. Just be careful not to exceed the maximum pressure rating for your tires.
A relatively recent technology for bicycles is the tubeless tire set-up. By using a conversion kit with a compatible rim or a tubeless wheel system and a compatible tire with a sealant, you can ride your bike without tubes! Unfortunately you can still pinch flat! When you pinch flat with tubeless though, the damage is done to your tire. For me this is a somewhat regular experience and tubeless mountain bike tires are expensive! When you pinch flat a tubeless mountain bike tire, you will notice that a small hole is formed just above the bead of the tire and it won't seal with sealant. So is that it? is your tire ruined? No!
You can patch a very small hole in a tubeless tire with rubber cement and a small piece of tube. First you want to remove the tire and clean up the area on the inside of the tire where the hole is really well. Also, clean all of the mold release agent off the piece of tube you are using Get all of the dried up sealant off the area you will be gluing the piece of tube to. After you clean the area up, take a piece of sand paper and lightly scuff up the area. Brush off the area a little with your fingers and then apply a light coating of rubber cement. Give the rubber cement about 45 seconds to a minute to get tacky, then apply your patch over the hole and voila! You tire is repaired and ready to be aired up again. I only recommend this procedure for very small holes. If you can see daylight through a hole, I don't recommend this technique.
3. Prematurely worn out cassette
It's a fact of life that drivetrain parts on a bicycle are wear items and will eventually need to be replaced. When a cassette gets worn out it often causes sluggish rear shifting performance and skips under hard torque. Have you priced drivetrain parts lately though? If it was just a chain to replace it would be pretty reasonable, but the cassettes are so expensive! I just got an 11 speed drivetrain for one of my mountain bikes and the cassette listed for over $300!
Here's a little secret about cassettes. Even the cheap ones are darn tough pieces of metal. The part that really wears quickly is the chain because it has many more moving parts. As a chain wears, it stretches and once it stretches past a certain point, it no longer lines up as well with the spacing of the teeth on the cassette. once the chain stretches to this point, it starts to eat into the cassette and the chain and cassette wear in together. Once this happens, the cassette is too worn out to use with a new chain, as the teeth will not match up with the new chain and it will cause skipping, which is dangerous.
You can avoid this by purchasing a chain wear gauge like a Park Tool CC-2. This handy little device will tell you how stretched out your chain is. Check your chain every couple hundred miles or so and when it reaches .75 mm of stretch over three links of chain replace it. You can get 4 or 5 chains or possibly even more out of one cassette this way. To help your chains last as long as possible, clean and lube your drivetrain with a proper chain lube frequently. WD40 has no business being near your bike! Use a real chain lube!
4. Grimy components
The last piece of advice brings us seamlessly to the this piece of advice. Keeping the moving parts of your bicycle clean and lubricated is important. Equally important is using proper lubricants. As I mentioned above, WD40 is not a lubricant, and should not be used on any part of your bike. Neither should motor oil, vegetable oil, transmission fluid, or any other random non-bicycle lubricant. Non-bicycle specific lubricants, at best, will attract dirt and grime and accelerate the wear of your drivetrain and other components. At worst, they can be highly corrosive and ruin parts in a matter of days. A proper chain lube will be dry after application and will not allow as much dirt and grime to stick to it. It will also last longer between applications and lubricate more effectively. This translates to a longer wearing drivetrain which saves you money in the long run.
5. Over-torqued fasteners
One of the biggest mistakes I see on a regular basis is over-torqued bolts. There's no excuse for this. Buy and use a torque wrench, especially if you have carbon fiber parts or frames and you do a little work or adjusting yourself. You'll save yourself the hassle of stripped out fasteners, from cracking expensive carbon fiber bits, but most importantly: money, time, and aggravation. If you can afford fancy carbon doodads for your bike, you can afford a basic torque wrench.
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