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.
Results 1 to 22 of 22
  1. #1
    mtbr member
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    Acquired my first bike. It's used. Where should I start?

    Hello MTBR! I traded my PS3 for a mountain bike on craigslist. I think it was a good decision! Here are the specs that I could find as I analzyed the bike and did some googling:

    2010 Trek 3900 Disc 18"
    Bontrager grips
    Giant Contact flat handlebar
    Fox RC2 dampers
    Marzocchi Bomber fork
    Giant seat
    NSS seatpost
    Mavic XE 325 Disc front rim
    Continental Baron 2.3 front tire
    Weinmann Goliath rear rim
    Continental Trail King 2.4 rear tire

    I have a few questions.

    1. I've visited the sticky thread about basic cleaning and maintenance to get a hang of that. It doesn't appear the bike has been used lately. There are small amounts of rust on various screws and such. What's a good way to remove rust? Will using something oil-based or WD40 to remove the rust attract more dirt?

    2. How do I know the fork is in good shape?

    3. One of the shifter covers is missing. Should I look for one on eBay or not sweat it?

    Glad to be hear. See you on the trail!

  2. #2
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    Fantastic trade. Anything that gets you off the couch, and outside riding is a good deal in my books.

    A little bit of rust on bolts I wouldnt be concerned about - that happens. More important is that the drivetrain components are cleaned and the chain is nicely lubed.

    Fork being in good shape - that really depends on what model of marzocchi bomber it is. I wouldnt worry too much about it initially - go out and ride it. If it is not getting full travel then look into whats going on.

    Shifter cover - I once busted one - I just put a piece of duct tape over it to keep dirt n grime out.

    Welcome to MTBR!


    Edit - Few other resources for bike maintenance :

    Sheldon Brown-Bicycle Technical Information - website of the late great Sheldon Brown. It looks crazy, but the wealth of information available is priceless.

    Park Tool Co. ยป ParkTool Blog - park tools site - excellent repair assistance for free!!!!

  3. #3
    mtbr member
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    006, thanks bud! Duct tape... brilliant. The only other rust I've noticed is where the seatpost meets the frame. I'll take some notes on my first ride. I made the trade and forgot I need to get a helmet before I can go out! Doh!

    Thanks for the warm welcome, friend.
    If you kill time, you'll bury opportunity.
    African Proverb

  4. #4
    R.I.P. DogFriend
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    Nubs, I am curious to know what model Marz fork you have on there. That bike was made for a 100mm travel fork. Hopefully it's not too 'franken-biked' with a long travel fork on there. Check to see if the seals on the stanchions are leaking any fluids, and look for scratches on the stanchions too.

    For maintenance tips and procedures, check out the Park Tool site mentioned above. Youtube is also a wealth of bike repair information, most of it legit too.

  5. #5
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    Congrats on the bike. That's a good call you made on the trade. PS3 is a pretty slick machine (I enjoy some gaming myself), but it ain't better than a bike, by a long shot.

    I've given a lot of bikes the old WD wipedown; it's a pretty good way to put a shine on them. Not much for removing rust, but it can't hurt, and it's gotta help keep it at bay a little at least.

    I also wouldn't worry a bit about a little rust on the bolts; totally cosmetic. And FWIW, I've run a front shifter for years and many miles (and all sorts of weather) without a cover and didn't have any issues. Duct tape fix would be fine.

    Have fun.

  6. #6
    rebmem rbtm
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    Fox RC2 dampers & Marzocchi Bomber fork ?

    Post some photos.

  7. #7
    mtbr member
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    Quote Originally Posted by jeffj View Post
    Nubs, I am curious to know what model Marz fork you have on there. That bike was made for a 100mm travel fork. Hopefully it's not too 'franken-biked' with a long travel fork on there. Check to see if the seals on the stanchions are leaking any fluids, and look for scratches on the stanchions too.

    For maintenance tips and procedures, check out the Park Tool site mentioned above. Youtube is also a wealth of bike repair information, most of it legit too.
    Whoa! Sounds like I better get it figured out if this thing is put together properly... Frankenbike... haha! Maybe take a look at my research/pictures posted below and throw me some quick headlines on your thoughts.

    Oh, and, thanks for the info! I will check for those things as I get around the bike on my initial maintenance. Thanks for pointing out YouTube. That's a great idea.

    Quote Originally Posted by slapheadmofo View Post
    Congrats on the bike. That's a good call you made on the trade. PS3 is a pretty slick machine (I enjoy some gaming myself), but it ain't better than a bike, by a long shot.

    I've given a lot of bikes the old WD wipedown; it's a pretty good way to put a shine on them. Not much for removing rust, but it can't hurt, and it's gotta help keep it at bay a little at least.

    I also wouldn't worry a bit about a little rust on the bolts; totally cosmetic. And FWIW, I've run a front shifter for years and many miles (and all sorts of weather) without a cover and didn't have any issues. Duct tape fix would be fine.

    Have fun.
    Thank you! I'm looking forward to it! I did love the PS3... my affections are heading outside though since I've started to look like I'm 6-months pregnant...

    I was wondering if WD would make it dirtier in the long run or create any complications since it's oil-based. You haven't had any issues?

    Quote Originally Posted by cobba View Post
    Fox RC2 dampers & Marzocchi Bomber fork ?

    Post some photos.
    I've got some photos posted below, along with a bit of a spec sheet based on what I could find on Google from what I saw on the bike.

    Make: Trek
    Model: 3900 Disc
    Year: 2010
    Color: Matte Orange
    S/N: WTU150C0437E/1039U0210

    FRAMESET
    Frame: Alpha White Aluminum w/semi-integrated head tube, bi-oval down tube w/integrated gusset, rack and fender mounts, disc compatible dropouts, replaceable derailleur hanger
    Size: 18"

    WHEELS
    Front hub: Formula Alloy DC20 front hub (stock $?)
    Front wheel: 26" Mavic XE 325 Disc ($100)
    Front tire: 26" Continental Baron 2.3 ($45)
    Rear hub: Shimano FH-M475 (stock $30)
    Rear wheel: 26" Weinmann Goliath 559x25 ($100)
    Rear tire: 26" Continental Trail King 2.4 ($20)

    DRIVETRAIN
    Shifters: Shimano ST-EF50-L, 8 speed (stock $?)
    Front derailleur: Shimano Nexave C051 (stock $?)
    Rear derailleur: Shimano Acera M360 (stock $22)
    Crank: Shimano Tourney M191 SIS 42-34-24 (stock $43)
    Cassette: SRAM PowerGlide II PG-830 11-32, 8 speed (stock $22)
    Pedals: Unkown brand, green nylon platform ($?)

    COMPONENTS
    Saddle: Giant ($30)
    Seatpost: NSS
    Handlebar: Giant Contact Flat ($46)
    Stem: Marzocchi 888 Direct Mount ($72)
    Dampers: Fox RC2 dampers ($?)
    Fork: Marzocchi 888 VF Bomber 200mm ($450)
    Headset: VP-A68-TK, 1-1/8" semi-cartridge, sealed (stock $?)
    Brakeset: Promax, mechanical disc w/Shimano EF50 levers (stock $?)

    Here's the gallery: 2010 Trek 3900 Disc - Imgur
    If you kill time, you'll bury opportunity.
    African Proverb

  8. #8
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    Quote Originally Posted by MatthewMiller View Post

    Here's the gallery: 2010 Trek 3900 Disc - Imgur
    Dang dude! Frankenbike fo sho! It's ALLLLIIIIIIIIVVVEEE!!

  9. #9
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    Wow!
    Yeti SB-66 Carbon

  10. #10
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    Please, for the love of god, do NOT use WD-40 on anything. WD-40 is a horrible compound. The only thing it does well is disperse water (hence 'WD'). Other than that, it gets gummy and sticky and attracts dirt, which is the opposite of what you want for anything on your bike. Despite popular belief, it is an absolutely terrible lubricant.

    If you need to lube something on your bike, use the proper lube. Chain lube for the chain, bearing grease for the bearings, etc. I also keep a can of PB Blaster all-purpose lube for small parts that need some light oil periodically, like derailleur hinges. Clean the frame with a rag and some warm soapy water. Don't worry about surface rust on the fasteners; it won't hurt anything as long as you can still get a screwdriver/allen bit in the head.

    The shifter is fine, as long as you keep dirt/debris out of it. I'd try not to to use duct tape on anything; duct tape leaves a horrible sticky residue that is nearly impossible to remove. And if any of that gunk gets in your shifter...

    As far as the fork, I bet you could sell it to someone who has a bike actually built for it, and use the money to get yourself a fork with the proper geometry to match the bike.

  11. #11
    Fat-tired Roadie
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    Wow.

    Normally I think people are being alarmist when they say this, but you're going to rip your head tube off.

    You might be able to get enough money out of that Marzocchi to buy a nice fork with a single crown and half the travel, that'll play well with the rest of the bike.
    "Don't buy upgrades; ride up grades." -Eddy Merckx

  12. #12
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    Quote Originally Posted by Starfury View Post
    Please, for the love of god, do NOT use WD-40 on anything. WD-40 is a horrible compound. The only thing it does well is disperse water (hence 'WD'). Other than that, it gets gummy and sticky and attracts dirt, which is the opposite of what you want for anything on your bike. Despite popular belief, it is an absolutely terrible lubricant.
    A WD frame wipedown w/ a rag is fine.

    FWIW, they also make a bike chain lube now that works quite well.
    Smells awesome too; almost good enough to wear.

  13. #13
    Fat-tired Roadie
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    If I cared more, I can imagine using WD40 to clean my chain. Since it's pretty volatile, I think I could follow it a little while later with a heavier oil and still have that stick okay. Its only problem is when people misuse it.
    "Don't buy upgrades; ride up grades." -Eddy Merckx

  14. #14
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    WD-40 would only really be good for your chain if you just drove through water and wanted to get it all out before dousing it in a thinner lube to remove all of the WD40. The problem with WD40 is that it has lots of both volatile and non-volatile compounds in it. The volatile compounds eat rubber, and the non-volatile compounds are terrible lubricants and attract dirt. Yes, the WD40 brand does have a chain lube which probably works great, but it's not true WD40.

    It does have a semi-redeeming property of allowing you to hose dirt/sand/mud off surfaces it's been coated with (which makes it handy for coating the steering linkage of a beater off-road truck with), but hosing off your bike isn't a fantastic idea. Sure, coating your bike's frame isn't going to directly hurt the frame, but it's also going to attract dirt, sand, and dust. I don't see how wiping the frame down with WD40 is better than using a rag and warm, soapy water. At least the water evaporates, leaving a clean surface that doesn't attract small particles.

    Sorry, I really hate WD40. It's one of those things that gets used entirely too much simply because it's been around for so long.

  15. #15
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    Good deal, since PS3s are going to be selling for super cheap when everyone has their ps4s.

    My advice:

    Sell the fork, and get a really nice single crown fork with something closer to 100-120mm travel.

    Check the frame for cracks around the headtube.

    Clean it up to you liking and ride that sucker!

  16. #16
    rebmem rbtm
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    Quote Originally Posted by AndrwSwitch View Post
    Wow.

    Normally I think people are being alarmist when they say this, but you're going to rip your head tube off.

    You might be able to get enough money out of that Marzocchi to buy a nice fork with a single crown and half the travel, that'll play well with the rest of the bike.
    I agree, that frame isn't made for that type of fork, it's made for a single crown fork with 80 to 100m of travel.

    * The RC2X & RC2 on that 888 fork is Marzocchi not Fox

    RC2: http://www.marzocchi.com/Template/Po...dOggetto=28193
    RC2X: http://www.marzocchi.com/Template/Po...dOggetto=28194

    888 RC2X (RC2X & RC2): http://www.marzocchi.com/template/de...Oggetto=28032#

  17. #17
    Clueless genius
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    I think we may need to see some pictures of this beast!
    2009 GT Sanction 2.0
    2007 C'dale Prophet 5
    1994 C'dale M400

  18. #18
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    Quote Originally Posted by Spykr View Post
    I think we may need to see some pictures of this beast!
    There is a link to the pics in post #7.

  19. #19
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    Quote Originally Posted by AndrwSwitch View Post
    Wow.

    Normally I think people are being alarmist when they say this, but you're going to rip your head tube off.

    You might be able to get enough money out of that Marzocchi to buy a nice fork with a single crown and half the travel, that'll play well with the rest of the bike.
    Would it even be worth it to replace the fork? If the previous owner rode the bike like this, it's kind of hard to tell what kind of condition the frame would be in.

  20. #20
    Clueless genius
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    Yes, it would definitely be worth it to replace the fork. You will however need to find a 100-120mm fork with a 20mm front axle, unless you want to replace your wheel as well. You'll also need a new stem with a normal mount (luckily you can find one those for not much money). I suggest looking for a 100mm dirt jump fork like a Rockshox Argyle, Marzocchi DJ or 4X, or a Manitou Circus.

    Look at the welds near the headtube for signs of cracking (jagged, dark lines, things like that). If there are any, part out what you can of the bike, and search for something new. If none, get a properly-sized fork for the bike and keep riding. It wouldn't hurt to bring it to a bike shop and have them check either, they likely won't even charge you.
    2009 GT Sanction 2.0
    2007 C'dale Prophet 5
    1994 C'dale M400

  21. #21
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    If you've got any local bike forums, you might have some luck working out a fork trade.

  22. #22
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    Quote Originally Posted by Spykr View Post
    Look at the welds near the headtube for signs of cracking (jagged, dark lines, things like that). If there are any, part out what you can of the bike, and search for something new. If none, get a properly-sized fork for the bike and keep riding. It wouldn't hurt to bring it to a bike shop and have them check either, they likely won't even charge you.
    That's what I was getting at. If the previous owner was treating this anything like a DH bike, the OP needs to be certain the frame is still in good shape before swapping out the fork. It may be fine, but I'm thinking the previous owner would have ridden the harder than the OP will, at least at first.

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