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 Post subject: Handlebar sizes ?
PostPosted: Tue May 07, 2013 4:42 pm 
Retro Guru
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Joined: Sun Oct 21, 2012 4:34 pm
Posts: 1396
Location: worthing
Hi all

Anyone come across handlebars that are not 25.4 or 31.8 ! , went to fit another set of bars to my 88 hardrock because the original shopper style ones are rusted to bits and just nasty only to find the stem wont clamp up tight enough :roll:

Cheers Paul


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 Post subject: Re: Handlebar sizes ?
PostPosted: Tue May 07, 2013 6:00 pm 
Gold Trader / MacRetro rider
Gold Trader / MacRetro rider

Joined: Sun Sep 04, 2011 11:33 am
Posts: 3098
Location: Riding my Woodsie.
Wikipedia says it better than I can!

Handle bar diameter

Both quill and threadless stems come in a variety of bicycle handlebar clamp diameters. The ISO standard for the clamping area of a handlebar is 25.4 mm (1 inch), which is used on mountain bikes and many Japanese-made road handlebars. However, the Italian unofficial standard is 26.0 mm, which is the most common clamp size for road bars. There are also intermediate sizes such as 25.8 mm to try to achieve compatibility with either an ISO or Italian stem, and the old Cinelli-specific size of 26.4 mm. In practice, many modern stems with removable faceplates allow for slight differences in handlebar clamp diameter, but the older type of stem with a single pinch bolt must be accurately matched. In the days of quill stems, a road stem was clearly identifiable from its "7" shape, but nowadays it can be hard to tell the difference between a "road" (26.0 mm) and "MTB" (25.4 mm) stem. Manufacturers frequently omit the clamp size from advertising or packaging.

BMX bikes usually have a 22.2 mm diameter clamp size.

A more recent standard is a 31.8 mm (1.25") clamp for both MTB and road bars. This is rapidly taking over from the previous mix of sizes, although other accessories such as some light or computer brackets may also need to be oversized to fit the thicker bars. Standard brake levers can be used as it is only the stem clamp central section that is oversized. Shims are available to fit a 31.8 mm stem to either a 25.4 mm or 26.0 mm bar, so many new models of stems are oversize-only.


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 Post subject: Re: Handlebar sizes ?
PostPosted: Tue May 07, 2013 7:55 pm 
Retro Guru
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Location: worthing
firedfromthecircus wrote:
Wikipedia says it better than I can!

Handle bar diameter

Both quill and threadless stems come in a variety of bicycle handlebar clamp diameters. The ISO standard for the clamping area of a handlebar is 25.4 mm (1 inch), which is used on mountain bikes and many Japanese-made road handlebars. However, the Italian unofficial standard is 26.0 mm, which is the most common clamp size for road bars. There are also intermediate sizes such as 25.8 mm to try to achieve compatibility with either an ISO or Italian stem, and the old Cinelli-specific size of 26.4 mm. In practice, many modern stems with removable faceplates allow for slight differences in handlebar clamp diameter, but the older type of stem with a single pinch bolt must be accurately matched. In the days of quill stems, a road stem was clearly identifiable from its "7" shape, but nowadays it can be hard to tell the difference between a "road" (26.0 mm) and "MTB" (25.4 mm) stem. Manufacturers frequently omit the clamp size from advertising or packaging.

BMX bikes usually have a 22.2 mm diameter clamp size.



A more recent standard is a 31.8 mm (1.25") clamp for both MTB and road bars. This is rapidly taking over from the previous mix of sizes, although other accessories such as some light or computer brackets may also need to be oversized to fit the thicker bars. Standard brake levers can be used as it is only the stem clamp central section that is oversized. Shims are available to fit a 31.8 mm stem to either a 25.4 mm or 26.0 mm bar, so many new models of stems are oversize-only.

Aah Wikipedia didnt think of that , its amazing , like some kind of encyclopedia :lol: think i will go and measure the old ones :D
Cheers Paul


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 Post subject: Re: Handlebar sizes ?
PostPosted: Tue May 07, 2013 8:24 pm 
BoTM Winner / Gold Trader
BoTM Winner / Gold Trader
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Joined: Fri Feb 26, 2010 12:36 am
Posts: 4715
Location: Burlington, ON Canada
There was another OS standard before 31.8. Tioga bars and Cube stems were 28.6. A number of companies (Axiom, Amoeba) made 28.6 bars, but the standard never caught on.


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 Post subject: Re: Handlebar sizes ?
PostPosted: Tue May 07, 2013 8:26 pm 
King of the Skip Monkeys
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Joined: Wed Nov 07, 2007 4:34 pm
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Location: Moomin Valley
I've got an old quill stem in 31.8mm...


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 Post subject: Re: Handlebar sizes ?
PostPosted: Tue May 07, 2013 8:31 pm 
Retro Guru
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Joined: Sun Oct 21, 2012 4:34 pm
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Location: worthing
Man its like some horrible plague sweeping the handlebar market :D


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