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  1. #1
    rain dog mainstreetexile's Avatar
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    Swapping handle bars, 31.8 -> 25.4, flat -> drop?

    My hybrid/touring bike came with an adjustable 1-1/8" threaded quill stem on it and I wanted to swap the stem out since it was flexing and creaking so much (and I haven't had to adjust it at all). I had a hard time finding a stem in that size, so I was happy to see one on nashbar w/ the same angle I've had my adjustable stem set at:

    http://www.nashbar.com/bikes//Produc...2_174788_-1___

    I ordered that stem a couple days ago (and I should receive it in 2-10 weeks or however long it takes nashbar to ship stuff) and I was reading some more about stems when I realized the clamp diameter on my handlebars is too big for that stem. I don't have any calipers but I roughed it out with a metric tape measure and it looks like it's an oversized flat handlebar with a 31.8 clamp diameter, while the clamp diameter for that stem I ordered is 25.4

    I was looking at Sheldon Brown's cribsheet for handlebar diameters here:
    http://sheldonbrown.com/cribsheet-handlebars.html

    If I were to get a new 25.4mm drop bar / touring handlebar (I was hoping I might be able to change eventually anyways), would I be able to use my existing brake levers and shifters on it? Based on that crib sheet it looks like they would both have the same grip size (23.8).

    If so, would it be practical to mount them on the top part of the drop bars and ride it like flatbars (w/ the added benefit of the extra hand positions)?
    Last edited by mainstreetexile; 10-17-09 at 01:35 AM.

  2. #2
    afraid of whales Mr IGH's Avatar
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    If you like your existing bars, why not go with an adapter and a modern stem? 1" bars are going away, the options for quill stemms are very limited these days. Everything you're buying new is becoming obsolete.

    http://www.performancebike.com/bikes...00_20000_57500
    IGH's, Dyno Hubs, LED lights and old frames

  3. #3
    GO BIG RED norwood's Avatar
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    Quote Originally Posted by mainstreetexile View Post
    My hybrid/touring bike came with an adjustable 1-1/8" threaded quill stem on it and I wanted to swap the stem out since it was flexing and creaking so much (and I haven't had to adjust it at all). I had a hard time finding a stem in that size, so I was happy to see one on nashbar w/ the same angle I've had my adjustable stem set at:

    http://www.nashbar.com/bikes//Produc...2_174788_-1___

    I ordered that stem a couple days ago (and I should receive it in 2-10 weeks or however long it takes nashbar to ship stuff) and I was reading some more about stems when I realized the clamp diameter on my handlebars is too big for that stem. I don't have any calipers but I roughed it out with a metric tape measure and it looks like it's an oversized flat handlebar with a 31.8 clamp diameter, while the clamp diameter for that stem I ordered is 25.4

    I was looking at Sheldon Brown's cribsheet for handlebar diameters here:
    http://sheldonbrown.com/cribsheet-handlebars.html

    If I were to get a new 25.4mm drop bar / touring handlebar (I was hoping I might be able to change eventually anyways), would I be able to use my existing brake levers and shifters on it? Based on that crib sheet it looks like they would both have the same grip size (23.8).

    If so, would it be practical to mount them on the top part of the drop bars and ride it like flatbars (w/ the added benefit of the extra hand positions)?
    Look at Sheldon's datasheet again. He's referencing 31.8 roadbars which do not have the same grip area diameter as 31.8 flatbars. Flatbar grip diameter is 22.2mm. Your flatbar controls will not fit. There are plenty around here who say that they will by spreading the clamps apart and some that have even done it. IMO that looks absolutely horrible and stupid.
    25.4 clamp diameter dropbars are getting very hard to find, not impossible but hard. A butterfly or trekking bar will provide added hand position and should allow use of the current flatbar controls.
    Decide what kind of bars you really want, buy the appropriate stem and controls. My advice is don't order parts before you're sure what will work.
    1996 Bianchi Veloce
    1993 Bridgestone MB-3
    1992 Trek 700
    1992 Trek 820

  4. #4
    rain dog mainstreetexile's Avatar
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    Thanks for the replies, it looks like I'll be eating the shipping and returning the new stem (I ordered it in addition to a couple other products I was getting from nashbar). I saw the threaded to threadless adapters before but didn't know about their quality, it seemed like it added another failure point. I also didn't see any 40deg rise threadless stems on nashbar, but i just searched and found one somewhere else (with 31.8 clamp):
    https://shop.sunrisecyclery.com/item/40546/

    Does anyone have experience w/ the threadless to threaded adapters? Do they have a minimum insertion line and let you adjust them up like a regular quill stem or are they meant to be plugged in all the way down to the headset? Also (I don't know if this is a dumb question) will the adapter that fits a 1 1/8" threaded headset have a 1 1/8" threadless cap on the top?

    I found a couple newer, lightly used 25.4 drop / ergo bars that looked great, but if my controls won't work on them I'll stick with my current flat bar since new controls is a bit cost prohibitive at this point. The trekking bars actually look like a pretty great solution, I had looked at them before but just saw brakes mounted on the front, now I see that it's more common to mount the controls on the bar ends and just use the other places for different hand positions.

    Does anyone know how the stem length varies for these compared to flat bars? I guess you'd need a longer stem to get a similar reach to the bars?

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