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  1. #1
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    Another dept-store bike question...

    Are the bottom-bracket bearings on dept store bikes generally upgradeable at all? Also are all the wheels on current MTB's the same O.L.D.?

    I am pondering building a HPV, but I don't have much of any bicycle parts on hand and what I am planning may not be ridable.... so what I want to do is, strip/cut up a dept-store MTB and use the pieces off it, just to see if I can get the thing to basically work. I have found a steel-frame 3x5-speed MTB for $80, which is easily less than I would pay rooting around for pieces separately online.

    If the HPV happens to work out fairly well then I'd want to upgrade some key parts, as I know that dept-store bikes tend to have lousy BB bearings (the bike comes with 1-piece steel cranks, so does that mean it's a BMX shell? And does that impose any limitations on my crank choices later on? I would want to put a cheap generic road triple in).

    Also the MTB only has 3x5 gearing, and I'd want to put a 9-speed wheel on it eventually....
    ~

  2. #2
    `````````````` CaptainCool's Avatar
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    If you're going to be stripping and replacing a bunch of parts, forget the department store and hang out on Craigslist and Ebay more.

  3. #3
    Senior Member Retro Grouch's Avatar
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    Quote Originally Posted by Doug5150 View Post
    Are the bottom-bracket bearings on dept store bikes generally upgradeable at all? Also are all the wheels on current MTB's the same O.L.D.?
    The answer to the bottom bracket question has changed a bit in the last year or two. A couple of years ago I would have advised you to upgrade to a Shimano cartridge bottom bracket that had the correct spindle length. Unfortunately, available of Shimano square taper bottom brackets is becoming spotty.

    Relative to the OLD question, while almost all modern mountain bikes have 135mm rear dropout spacing, the 5-speed freewheel thing would cause me to wonder. Sometimes 1 measurement is worth 1,000 guesses.

  4. #4
    Senior Member Bill Kapaun's Avatar
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    You have to be leery of many of the parts.
    The bike may say "Shimano equipped", but the hubs, cranks etc. are the cheapest available.
    I picked up a 91 TREK 820 on CL for $20. It was beat up pretty badly and one of the shifters was garbage, but it had a VERY usable Free Hub/cassette on the back.
    I put on a friction shifter from an old Roadmaster that was given to me and use it as my back up bike. The rear wheel assembly got swapped to my my primary bike. The Roadmaster frame was victim to the hacksaw!

  5. #5
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    Quote Originally Posted by CaptainCool View Post
    If you're going to be stripping and replacing a bunch of parts, forget the department store and hang out on Craigslist and Ebay more.
    The problem there is that I want to use steel for the frame (because it's easier to weld than aluminum) and around 97% of all cheaper bikes now use aluminum frames. I'd spend a lot of time searching through aluminum bikes just looking for the few steel ones, that may still have rust or other damage. And eBay would likely involve shipping charges, so I'm thinking paying $80 for a new steel bike (that wal-mart will deliver to the store just down the street for free) is a pretty good deal.

    Quote Originally Posted by Retro Grouch View Post
    The answer to the bottom bracket question has changed a bit in the last year or two. A couple of years ago I would have advised you to upgrade to a Shimano cartridge bottom bracket that had the correct spindle length. Unfortunately, available of Shimano square taper bottom brackets is becoming spotty.
    All I'd want is to switch from cheap 1-piece crank to a cheap 3-piece crank that could take (cheap) road rings. Is this the right part?
    http://www.bikepartsusa.com/cgi-bin/...ets-conversion
    I thought that bottom brackets came in different widths, but bikepartsusa only sells one single conversion BB kit.

    Quote Originally Posted by Retro Grouch View Post
    Relative to the OLD question, while almost all modern mountain bikes have 135mm rear dropout spacing, the 5-speed freewheel thing would cause me to wonder. Sometimes 1 measurement is worth 1,000 guesses.
    I'd need to set the rear end spacing anyway, I'll just have to measure to make sure the OEM wheel is 135....
    ~

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