1. The most important thing about buying a new bike is to make sure it fits. The only way you'll know if the bike is right for you is to size up the bike and make sure that the bike's geometry matches your body's geometry. Ask questions and do some research.
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2. If possible, try to find a shop that will let you demo the bike on real dirt. Five minutes in a parking lot won't cut it. You wouldn't buy a car without a real world test drive, and a bike should be no different.
3. Don't belive the hype. Just because your favorite rider or best friend rides a certain bike, that doesn't mean that's the best one for you. Have an open mind and be realistic about your needs and ability.
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  1. #1
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    Creaking noise on new trek marlin

    so I bought this Marlin from the LBS about two months ago. while going on a short ride around base (stationed on an AF base) I quickly noticed that my left crank arm (non drive side) came loose. I stopped riding and got the bike home. I took the bike to the LBS and had the guy tighten the crank back up (didn't torque). A few weeks later I'm now getting an annoying Creaking noise when heavy load or when i stand up, I think I've isolated the noise to the left Crank arm when standing on either pedal. can anyone point me in the right direction?

  2. #2
    Fat-tired Roadie
    Reputation: AndrwSwitch's Avatar
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    Sounds like you already know.

    Bikepedia says the 2013 Marlin (is that the right one?) has a Shimano Altus crank. IIRC, that usually has a square taper bottom bracket. The crank arm fixing bolts need to be quite tight for that system. So you might be okay if you take it back to the shop and have the mechanic really wail on it. It wouldn't hurt to use a torque wrench. This is one of the only bolts on a bike that requires some reasonable number of foot pounds.

    Riding around with a square taper crankset loose enough to have play can damage the bore in the crank arm. So it may be toast. That would suck, so fingers crossed. Though as new as the bike is, you may be able to warranty it.

    I could also be wrong about the bottom bracket type. If it's splined, it takes much less torque. In that case, taking the arm off, cleaning everything, greasing everything and reassembling might solve it.

    Finally, this could be a problem with something else. Seems unlikely since you had a problem with your crank recently. But, the pedals, seat post, headset and handlebar interfaces all are relatively common culprits and almost everything can creak. The frame tubing will sometimes mess with where sounds seem to come from.
    "Don't buy upgrades; ride up grades." -Eddy Merckx

  3. #3
    Picture Unrelated
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    Andrw nailed it as usual. I would add that the bottom bracket is another frequent location for creaking to come from. If you aren't afraid of buying tools and working on things I would buy a crank puller and a bottom bracket tool for your particular bike and do a bit of work:

    - Remove both crank fixing bolts and pull both cranks using a crank puller.
    - Remove the bottom bracket. Remember that one side is reverse threaded.
    - Clean and grease the BB shell (where the threads in the frame are).
    - Grease threads and install BB torquing sufficiently.
    - Clean any excess grease from the BB square taper surfaces and inside of crank arm square mating surfaces.
    - Reinstall crank arms to sufficient torque.

    If you ride a lot (or if your cranks have had a history of coming loose) the crank arm fixing bolts are something you're going to need to check every few rides. Buying a long handle 8mm is probably a good investment. The BB probably doesn't need to be re-greased, but since you're going to have most of the parts off it's a good exercise and something you'll want to repeat a few times a season just for good measure.
    Don't you hate it when a sentence doesn't end the way you think it octopus?

  4. #4
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    Once a square taper crankarm has been ridden loose for any length of time it will never stay tight again, no matter how tightly it is torqued down. Yours may be fine but if it isn't and that is the source of your creaking they owe you a new one IMO.

    Then again the creaking may well be something else. I would utilize the lbs and have them track the problem down, that's what they are there for.

  5. #5
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    the mechanic should have cranked both those bolts down to 29-30 foot pounds before the bike even went on the sales floor. the fact that he did not torque it after it was a problem leaves me with very little faith in this shop. if the arm came loose, it probably damaged the inside of the crank arm square interface and it's never going to go in there and stay tight again. you should have the shop go over that bike THOROUGHLY to make sure everything is torqued correctly.

    if the crank is damaged, it's their fault for not torquing it in the first place, and they owe you a brand new crankset. that mechanic is owed a slap in the face for making everyone in my profession look like a moron.

  6. #6
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    Yeah I'm stationed here in S. Korea and the LBS just put the wrench on it and used some "umph" on it. I'll take it back in and get it checked out and hopefully I can work on getting him to dig around a little more. Thanks a lot for the input everyone!

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