Another Update
I paid very close attention this morning during my commute and I got the chain to "slip" 3 times. I believe that M8547 is correct that indexing was the problem. I think that the 3-3 gear is particularly finicky in that it sometimes rides on top of 3-4 and then fully engages under load making the pedals jerk.
I had tweaked the shifting and thought I had it dialed in, I guess it needs a bit more tweaking. If I understand how this works, I should be turning the barrel dial counterclockwise a bit so that downshifting is easier. is that correct? I usually go by 1/4 turn increments.
Unresolved question
It appears to me that my chainring needs replacement, can anybody confirm based on the picture? Should I just run it until it croaks and then just replace the entire drivetrain or should I replace the crankset and chain now to save the cassette that I put in recently?
I would rather not replace my cassette if I don't have to. For reference, I replaced it last year so it has about 3-4000 KMs with a new chain.
Yep, it's good to look at it closely to see what it's actually doing.
It might not be as simple as adjusting the barrel adjuster. This kind of problem could be caused by:
Worn chain or cassette
Barrel adjuster needs fine tuning
Derailleur hanger is bent
Cables or housing are sticky/dirty/worn
Derailleur does not move/pivot freely
When I originally read about your issue, I thought you had a new chain and cassette, so I had ruled those out. If you put a new chain on with an old cassette, it will very often cause the problem you seem to be having. Unfortunately not all chains and cassettes last a long time. My commuter bike has a 7 speed drivetrain, and I've found those parts don't seem to last as long as they should because no one is making good quality 7 speed parts any more. On my mountain bikes the Shimano XT or similar level cassettes seem to have lasted the life of the bike so far. But on my commuter it seems to need a new cassette with every chain, maybe once or twice a year.
I don't think it's unreasonable to have to replace a cassette after 3-4 thousand kilometers. (3-4 megameters?) It would be nice if it lasted longer of course. It looks like a cassette should cost $20-50. To change it yourself you need a cassette remover tool (90% chance it takes a Park FR-5G. The FR-5G is better than the FR-5, IMO.), a wrench that fits the cassette remover tool (I think it's 1", or most adjustable wrenches will fit), and a chain whip which holds the cassette as you loosen the lockring. I have three bikes so it makes sense for me to own these tools, but if you have a bike shop do it, it should be cheap. It's literally a 1-minute job to simply change the cassette.
That chainring doesn't look too bad. There is some wear, but I wouldn't replace it unless it's causing a problem. I don't think there's much downside to running a chainring that's a bit worn, except that it might not shift as well between chainrings. I don't think a worn chainring will damage a new chain (unless it's really bad, in which case it probably just won't work right). The chainring, especially the large 44T (or 42T or whatever), spreads the force out over a lot of links on the chain, much more than the 11T gear on the cassette, which only has 5-6 teeth taking the same force. Plus, I don't think that the tooth-tooth spacing on the chainring changes much even if the chain stretches. It's a function of radius and number of teeth, so a worn chain might ride slightly higher on the teeth, but I think a new chain will still find the correct spot. And finally, I don't think chains really stretch that much any more. Most chain stretch tools measure roller wear as much as stretch, and while chains do wear out, generally they stop shifting well long before they stretch.
Here's what a brand new chainring might look like:
http://brimages.bikeboardmedia.netdna-cdn.com/wp-content/uploads/2010/11/shimano-105-component-group-crankset-chainwheel05.jpgThe smaller ring has symmetric teeth because there's nothing smaller for the chain to shift to. The larger one has asymmetric teeth, some that are different, and some special shapes below the teeth to facilitate shifting. If your chainring bolts look like the one in the picture, they are not riveted, but you need a chainring bolt tool on the inside and usually a hex key (a few are torx star) on the outside. The chainring tool is cheap, like $5.
http://www.rei.com/product/750478/park-tool-chainring-nut-wrenchTo address some of your other issues...
The seatpost creak could literally be anything, even if it sounds like it's coming from the seatpost. It can be really frustrating to track down this kind of issue. What you need to do is try to isolate where it's coming from. For example, if it ever does it if you are pedaling while standing up, it's not the seatpost.
- Check that all the bolts are snug. How tight generally depends on the size of the bolt, so if it takes a big hex key like 6mm it needs to be a lot tighter than something that takes a 4mm hex key.
- Clean and/or grease areas where there might be metal on metal, like the seat rails, the seatpost itself where it goes in the frame.
- Don't rule out other parts of the bike unless you are sure you can eliminate them. Creaking can be caused by the seat, handlebars, pedals, chainrings, crankset, hubs/wheels, or even a cracked frame. One time a loose quick release on one of my wheels cased a creaking that took me a few weeks to track down.
If the wheel is out of true as a result of a crash, there's a good chance it might not be able to be trued. For small bumps it can usually be adjusted, but often a major crash will bend the wheel to the point where the spokes can no longer hold it straight while still having a reasonable amount of tension. Wheel truing is a bit tricky until you get the hang of it, so it may be best to take it to a shop and have them true it, or find a community bike organization where someone will teach you and work with you.
In general I would lean towards keeping the bike, but in the end it's up to you. A new bike is cheaper than all the parts purchased individually, but if just a few parts need replacing it's usually better to just replace them. I would consider a new bike if the wheels (both), frame, or entire drivetrain need to be replaced. For example, if you can't fit sufficiently skinny tires on your wheels, or if you wanted to upgrade to a drivetrain with more speeds, which means all new parts including shifters. Or if the frame was broken or the wrong size or style. Just be careful that you don't get a new bike that's too cheap. A lot of low-end bikes have parts that are inferior or difficult to maintain. I've seen riveted chainrings, weak and poorly engineered metal and overuse of plastic, outdated parts like square taper bottom brackets to limit compatibility, etc. I don't know if you can get a good bike for $2-300, but I haven't looked at hybrid bikes. That's a good bit less than I, personally, would spend on a new road or mountain bike, but I like nice bikes!
I have a 1999 Trek 720 that's been my daily commuter for the past six years. What you have could make a great commuter bike if you can find good tires, or an even better winter commuter bike with mountain bike tires, or you could sell it and get something that suits your needs better if you don't like it.
I hope this helps! If you want to learn more about bike maintenance on your own, I recommend a book like one of Lennard Zinn's, or the Park Tool website.
