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  1. #1
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    Technical Questions on how to convert race/drop handlebars to flat bar.

    Hi, I currently have a fixed gear/single gear bike with a drop bar and two dropbar style brakes.

    The specs for the stem on this bike state:
    "Forged Aluminum, 8 deg, Removable 26.0 Clamp, Black Finish, Threadless 1.125" It's not clear to me what these measurements, particularly 26.0 and 1.125, mean.

    I also have an extra flat bar which I tried to install but the stem (above) was too big for it. The handle bar has no measurement markings so I measured the circumference twice and divided by pi and got 25.2 and 25.26 mm. The online store I'm chatting with insists this a 25.4 mm handlebar. But I see 25.2 mm handlebars online being sold online (here). Although Sheldon Brown doesn't mention a 25.2 mm anywhere either.

    My online store also suggest I get a new stem. I don't understand why I can't buy a shim?

    My online store also indicates I need to get new brake cables because the current cable endings that are on the dropbar won't fit the new brakes for the flarbar I need.

    Anyway here is a summary of what I need and any help will be appreciated!

    - Is my extra flat handlebar indeed a 25.4mm or is it really a 25.2mm? This is where everything starts.
    - Do I really need to get new brake cables to convert from dropbar brakes to flatbar brakes? If so any recommendations?
    - So I really need to by a new stem (see dimensions above)? Why can't I simply buy a shim? If so any recommendations?
    - Any suggestions on grips?
    - Are there conversion bundles I can get that has all of the above?

    Your help and advice is appreciated.

    Thanks!

  2. #2
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    The handlebar could be either one. Since your stem is 26.0mm, you could probably just get a couple of 0.2mm shims and use either 3 or 4 of those. And yeah, you need new cables as well. You might be able to MacGuyver up a solution without new cables, but cables are cheap. You probably don't need a new stem.

    For flat bars, I'd like something like Ergon grips - they look funny, but they're comfortable.

    All of these questions (and more) could be fielded by a competent bike mechanic who has the bike in front of them - if you're not 100% sure what you're doing, I'd at least see what he says.
    馬好き

  3. #3
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    Quote Originally Posted by umazuki View Post
    The handlebar could be either one. .....
    Umazuki, thanks. Are you CONFIRMING there are 25.2 mm handlebars? If so can you post a reference (other than the ebay link I cited)? I can't find any mention of a 25.2 mm handlebars anywhere else. Sheldon doesn't mention such a beast either. I'm wondering if my measurement tolerances are within the margin of error making this indeed a 25.4 mm handlebar. Thoughts?

  4. #4
    absent Ferrous Bueller's Avatar
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    Quote Originally Posted by megabyzus View Post
    "Forged Aluminum, 8 deg,Means the stem angles 8 degrees up or down from perpendicular to the steerer tube.
    Removable 26.0 Clamp Is the handlebar clamp diameter. 26.0 is a common drop bar size.
    Threadless 1.125" Is the clamp onto the steerer tube of the fork and is common for both road and MTB.

    - Is my extra flat handlebar indeed a 25.4mm or is it really a 25.2mm? This is where everything starts. Assume that it's 25.4
    - Do I really need to get new brake cables to convert from dropbar brakes to flatbar brakes? If so any recommendations? Yes. Get decent ones which come packaged with inners and outers. Make sure the inners have sideways cylinder ends for MTB brakes.
    - So I really need to by a new stem (see dimensions above)? Get the 25.4 stem. You'll be happy you did.
    - Any suggestions on grips? Comfort or control? Ergons (as mentioned) for comfort, Grippy narrower cylindrical grips for control.
    - Are there conversion bundles I can get that has all of the above? Not that I've heard of.
    Comments in bold.

  5. #5
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    Thanks for the info. Great appreciated.

  6. #6
    Senior Member Retro Grouch's Avatar
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    A bicycle is a simple machine but the devil is in the details.

    1. Sometimes 1 measurement is worth 1,000 guesses. If you aren't sure of the clamping diameter of your handlebar, and you don't have a metric caliper, wrap a piece of paper around the handlebar, mark where it overlaps, measure with a flat ruler and divide by pi.
    2. You don't need a different stem to make your bike work, but you might want one anyway. If it was my bike, I'd try it with what I had and see how it feels.
    3. I've made shims for undersized handlebars from an empty soda can. In 1989 Greg LeMond won the Tour de France using such a shim so I'm in good company.
    4. You really will need different brake cables to fit flat bar style brake levers. Unless your cables are pristine, you'll probably need new cables anyway. You might need longer brake cable housings too.
    5. What are you planning to use for shifters and brake levers? That might drive your handgrip decision. There's lots of choices, I'm partial to natural cork myself.

    Try to have fun with your project. I can almost guarantee that you'll find every step of the process more frustrating than you think. You'll learn a lot about bikes through the process, however, and you'll be a lot smarter when you finish.

  7. #7
    Senior Member cyclist2000's Avatar
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    What type of shifters do you have on your current bike, down tube? The brake levers probably won't work, and what type of brake are on the bike.
    I don't do vintage, I bought them new, rode them, kept them. Now they are just old bikes
    http://www.flickr.com/photos/bustercrb/sets/72157623483647522/

  8. #8
    absent Ferrous Bueller's Avatar
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    Quote Originally Posted by cyclist2000 View Post
    What type of shifters do you have on your current bike, down tube? It's a FG/SS. First sentence in the thread.
    The brake levers probably won't work...He knows this and is buying new levers and cables (5th paragraph).
    Comments in bold

  9. #9
    Senior Member TromboneAl's Avatar
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    Save yourself some trouble and expense, and don't make the same mistake I made.

    You already have a flat bar installed -- it just happens to have drops on the side!

    Instead of installing a new handlebar, you can learn to use the brakes with your hands on the hoods (preferred -- they are designed to work this way), or you can buy and install some "inline" or "interrupter" brakes on the top bar:




    I spend 99% of my time with my hands on the top, and it works fine.
    My Book: Drive, Ride, Repeat: The Mostly-True Account of a Cross-Country Car and Bicycle Adventure

  10. #10
    absent Ferrous Bueller's Avatar
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    ^that's exactly what I'd do too

  11. #11
    Senior Member cyclist2000's Avatar
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    Isn't the simplest thing to do is get out the hacksaw and cut off the drops or turn the bars over and cut them to bullhorns and use the current brake levers
    I don't do vintage, I bought them new, rode them, kept them. Now they are just old bikes
    http://www.flickr.com/photos/bustercrb/sets/72157623483647522/

  12. #12
    coprolite fietsbob's Avatar
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    The steerers are 9/8" so you buy a stem to go with the other bars..

  13. #13
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    Hi,

    Chop and flip the drops into bullhorns,
    not new cable or brake levers needed.

    Might need some new handlebar tape
    depending on the stuff currently fitted.

    rgds, sreten.

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