My sister, who lives way out in the middle of nowhere, has got a fairly modern upright hybrid. It is either a 2009 or 10 giant bike. She has been bugging me that she wants a more upright handlebar rather than the flat bars her bike has. I wanted to buy a set of handlebars that come up more. Will I be safe in getting some handlebars that are 25.4? She'd probably have a hard time removing the grips to check what it says as to the width.

You need to look up the specs for her model of bike. 31.8mm is the new standard, but some mountain bikes and hybrids still use 25.4 and some road bikes still use 26.0.

edit: Oh, and the diameter might be stamped on the middle of the bar instead of the ends, and the stem is probably marked somewhere as well (could be on the inside, so you'd have to remove the face plate).

if you want to play it safe, then get a 25.4mm bar and a 31.8mm to 25.4mm shim.
Even if you end up not using the shim, it never hurts to have them around.

The difference between 31.8 and 25.4 is pretty big. With 25.4mm clamp, the diameter only slightly tapers to 22.2mm for the rest of the bar. With a 31.8, this taper to 22.2mm is very dramatic. Maybe she can look at it and measure if it looks like it is 1" or 1 1/4" wide?

I'd suggest using a coin for comparison, just to make sure. A quarter is just about 25.4 mm across. It makes a good baseline for comparison.

""" The ISO standard for the clamping area of a handlebar is 25.4 mm (1"), 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 and 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 are quite accommodating of slight differences in handlebar clamp size, 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. A new standard is an "oversize" 31.8 mm or 31.7 mm (1.25") clamp for both MTB and road bars."""

From wikipedia

don't have to do that.. tape measure will do..

IF you mean width you go from one end to the other, otoh. If You meant Diameter..

As mentioned before on this list.. wrap a piece of paper 1 or 3x around the bars, mark it,
unwrap it and you have a distance, circumference, to calculate the diameter From.

If she's not very mechanical the strip of paper wrapped around and marked where it crosses the first end is a good way to find the circumference. Be sure she does this right near the stem's clamp.

If it's a cheaper hybrid I'd say it's 99.99% certain to be 25.4. But the 31.8 standard is beginning to filter down from the high end bikes to some of the mid price models. So depending on what the bike cost there may be some room for uncertainty.

Thanks for the help. For the measuring part, she should measure at the center of the handlebar, right?


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where the asterisk is above. this is the fatter part of the handlebar that has those grooves.

Or any part of the handlebar? Thanks, again.

No, immediately to the side of the stem, no sense in trying to remove the bar first and the knurled part of the bar is not best.

Post a good pic of handlebar and pretty much anyone here should be able to tell you in an instant.